The Lens A Practical Guide for the Creative Photographer

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The Lens

NK Guy

The Lens A Practical Guide for the Creative Photographer

NK Guy, photonotes.org Editor: Joan Dixon Copyeditor: Judy Flynn Layout: Petra Strauch Cover Design: Helmut Kraus, www.exclam.de Cover photos: NK Guy Printer: Everbest Printing Co. Ltd through Four Colour Print Group, Louisville, Kentucky Printed in China

ISBN 978-1-933952-97-0 1st Edition 2012 © 2012 NK Guy Rocky Nook, Inc. 802 E. Cota Street, 3rd Floor Santa Barbara, CA 93103 www.rockynook.com

Library of Congress Cataloging-in-Publication Data Guy, NK. The lens : a practical guide for the creative photographer / by NK Guy. -- 1st ed. p. cm. ISBN 978-1-933952-97-0 (pbk.) 1. Photographic lenses. I. Title. TR270.G89 2012 771.3’52--dc23 2012001393

Distributed by O‘Reilly Media 1005 Gravenstein Highway North Sebastopol, CA 95472 All product names and services identified throughout this book are trademarks or registered trademarks of their respective companies. They are used throughout this book in editorial fashion only. No such uses, or the use of any trade name, are intended to convey endorsement or other affiliation with the book. No part of the material protected by this copyright notice may be reproduced or utilized in any form, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission of the copyright owner. While reasonable care has been exercised in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. All photographs, screenshots, example layouts, and illustrations by the author. This book is printed on acid-free paper.

For Mum For always working tirelessly to make everything possible

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Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Why interchangeable lenses?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What can interchangeable lenses do for me? . . . . . . . . . . . . . . . . . . . . . . . What’s covered in this book? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What’s not covered in this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 2 3 5 7

1 1.1 1.2 1.3 1.4

A brief history of optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The science of light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The path to the lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geometrical optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Waves and particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10 10 10 16 17

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22

Bending light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Putting glass to work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What is a lens? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Field of view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Focal length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . But what is focal length, really? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prime or zoom: adjustable focal lengths . . . . . . . . . . . . . . . . . . . . . . The 35mm focal length equivalent . . . . . . . . . . . . . . . . . . . . . . . . . . . Digital versus film: the cropping factor . . . . . . . . . . . . . . . . . . . . . . . APS-C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Medium format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Focal length examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Image circles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . All about apertures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f-stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maximum apertures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fast and slow lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adjusting the aperture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wide-open metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Depth of field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

20 20 21 21 23 24 26 28 28 30 31 34 34 35 35 38 39 41 42 44 45 45 46

3 3.1 3.2 3.3

Lens mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What’s in a lens? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A lens that fits: lens mounts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Popular lens mounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

52 52 53 54

3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22 3.23 3.24

Motors and mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ultrasonic focus motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Motion blur. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The handheld rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizers: a lens not shaken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The user interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . To infinity—and beyond! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What’s in a name? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alphabet soup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decoding a lens name. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Serial numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Build quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens barrel construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens marketing categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Notable marketing categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Colored rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kit lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . White lenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cold weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

54 56 57 58 59 62 66 66 67 68 69 70 70 70 72 73 75 76 77 78 79

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Choosing the right lens for a project . . . . . . . . . . . . . . . . . . . . . . . . 82 Choosing a lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Portraits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Landscapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Kids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Closeup or macro photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Sports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Traveling light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 The reporter’s triumvirate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Low-light and night photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Wildlife photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9

Choosing a lens by focal length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wide angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Extreme wide angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fisheyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Normal or the Nifty Fifty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Telephoto. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Super telephoto . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Megazooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A matter of perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Perspective in portraits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

106 106 108 109 115 117 120 122 124 124

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5.10 Falling backwards: another take on perspective . . . . . . . . . . . . . . . 127 5.11 Compressed perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8

Accessorize! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Teleconverters and extenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Supplementary lens focal length adapters . . . . . . . . . . . . . . . . . . . . Macro accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tripod mounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

136 136 149 152 154 155 160 160 161

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7

Buying lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Camera brand or third party? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Where to buy? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The dark side of camera retailing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Warranties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The gray market . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Going used? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rental options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

164 164 166 169 170 171 171 172

8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 8.20 8.21

Advanced topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Learning more about optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What is focal length? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens element types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optical properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seeking the perfect lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optical flaws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chromatic aberration: color fringing . . . . . . . . . . . . . . . . . . . . . . . . . . Spherical aberration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aspheric lens elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Intentional spherical aberration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Other aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sharpness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lens flare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Antireflective lens coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multicoatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bokeh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vignetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Close focus distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The hyperfocal distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

176 176 176 180 181 183 184 184 185 189 190 191 192 194 196 196 199 200 203 205 206 206

8.22 8.23 8.24 8.25 8.26 8.27 8.28 8.29 8.30 8.31 8.32 8.33 8.34 8.35 8.36 8.37 8.38 8.39

The diffraction limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diffractive optic lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tilt and shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lenses for video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mirror lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “Digital” lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scratches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cleaning lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keeping out the weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fungus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Infrared photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The mystery of MTF charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A measurable obsession. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sample variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Micro focus adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Testing for focus errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

209 209 210 216 220 221 222 223 224 225 226 226 227 230 232 233 234 234

9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12

Creative options: beyond the standard lens . . . . . . . . . . . . . . . . . Manual-focus lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adapting lenses to other camera systems . . . . . . . . . . . . . . . . . . . . . Focusing manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modern manual-focus lenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Toy cameras and lo-fi photography . . . . . . . . . . . . . . . . . . . . . . . . . . . Diana lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A flexible approach: the Lensbaby . . . . . . . . . . . . . . . . . . . . . . . . . . . . Creative bokeh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pinhole cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detaching the lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fake anamorphic effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Homemade lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

238 238 239 247 250 250 252 253 257 258 258 259 259

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 Appendices Appendix A: Lens mount systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix B: Manufacturer-specific lens terms . . . . . . . . . . . . . . . . . . . . . Appendix C: Lens mount table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix D: Chapter Opening Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix E: A simple focus test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

264 275 278 280 282 284 288 304

ix

TA B L E O F C O N T E N T S

INTRODUCTION

2

IN TRO D U C TIO N

Introduction Why interchangeable lenses? Which lens should I buy for my camera? Such a simple question, but it’s actually one of the most important photographic decisions you can make. Nothing affects the technical quality of a photo more than the glass. Lenses are at the very heart of the image-forming process. They’re not a peripheral, and they’re not an accessory. Many new photographers put a lot of effort into choosing the right camera, but leave the lens as an afterthought. Lots of people rarely venture beyond the standard kit lens that came in the box. This is partly because of the expense. But it’s also because shopping for lenses is frankly very confusing: there’s such a panoply of choice covering every price point imaginable.  Whether you’re shooting with a huge professional digital SLR like this Canon EOS 1D Mark IV, or a tiny pocket camera like this Pentax Q, interchangeable lenses give you total flexibility.

Sticking with the kit lens just doesn’t take advantage of the incredible versatility of an interchangeable lens camera, though. The ability to swap lenses gives you amazing photographic scope. Take in vast sweeping scenes with a wide angle lens. Capture faraway birds with a telephoto lens. Record the tiniest detail of a flower with a macro lens. Take the perfect portrait with a prime lens. All this and more is possible when you choose the right lens for the job! So that’s the inspiration for this book. It’s not a simple buyer’s guide listing the specs for various lenses. You won’t find out whether the SuperLens 70–300 3.5–4.5 lens is sharper than the MegaGlass 100–200 2.8 lens at

200mm. That sort of specific comparative data has very narrow utility. Instead, this book gives you all the information you need to make educated buying decisions based on your needs, priorities, and budget. The Lens will help you build the perfect lens collection to suit your needs—now and in the future.

What can interchangeable lenses do for me? Check out some of these before and after shots. The befores are what you might see using a standard manufacturer-supplied kit lens. The after shots were taken using specific lenses suited for each shoot.

▲ This view of Arundel Cathedral in Arundel, England, doesn’t really show the scale of the building’s interior.  However, this wide-angle shot of the same cathedral reveals the grandeur of the rib-vault ceiling.

▲ The fishing village of Beer in Devon, England. Picturesque, but what if you want to take a closeup of the seagull? If you move too near it’ll fly away.  One solution is a telephoto lens, which lets you zoom in close to the bird without frightening it.

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W H AT C A N I N T E R C H A N G E A B L E L E N S E S D O F O R M E?

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IN TRO D U C TIO N

▲ Low-light photography is always challenging. Here’s a typical blurry shot caused by attempting a photograph in dim light without flash.  But by using a lens capable of admitting lots of light—a “fast” lens—a sharp low-light photo is possible even though the candles are the sole light source.

▲ The Galeries Lafayette department store in Paris is famous for its massive 1912 Art Nouveau glass dome. This first shot shows the detail of the dome, but doesn‘t really give a sense of scale for the space.  A circular fisheye lens, while distorting the image considerably, yields a much more dramatic view.

What’s covered in this book? There are three basic categories of interchangeable lens cameras covered by this book: single-lens reflex (SLR) cameras, mirrorless interchangeablelens digital cameras, and rangefinders.

SLRs Single-lens reflex (SLR) cameras are the traditional midsize camera body. They almost always allow for interchangeable lenses and have a large hump on the top that houses a prism or mirror. When you look through the viewfinder, you look straight through the main lens via a mirror, hence the name. SLRs date back to the 35mm film era, though many SLR designs have been successfully brought into the digital age. This book deals with both film and digital SLR cameras with imaging areas the size of 35mm film or smaller. Canon, Nikon, Olympus, Pentax, and Sony are makers of popular SLRs.  A Canon EOS 5 SLR. This fully automated 35mm film camera was introduced back in 1992 and represents an early EOS design. Also marketed under the name A2E.

Digital mirrorless Digital mirrorless interchangeable-lens cameras are compact and portable. They’re smaller than SLRs on the whole and lack the big SLR mirror/prism hump. As the name describes, they’re digital only and don’t have the reflective mirror assembly that takes up a lot of space inside every SLR. They’re sometimes jokingly referred to by the acronym EVIL, for electronic viewfinder interchangeable lens, or more accurately as MILCs, for mirrorless

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W H AT’S C O V E R E D I N T H I S B O O K ?

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IN TRO D U C TIO N

interchangeable lens cameras. Throughout this book I will refer to them simply as mirrorless cameras. Fujifilm, Nikon, Leica, Olympus, Panasonic, Pentax, Samsung, and Sony are some well known makers.  The X-Pro1 is the first of a line of mirrorless digital cameras from Fujifilm. Shown are three lenses introduced with the camera.

Rangefinders Rangefinders have a very old design, dating back to film cameras of the 1930s. They use two separate lens systems: one that sends light to the film or image sensor and one that is used strictly for the viewfinder. They have a complex internal array of mirrors and lenses to enable focusing. Nikon and Canon both made rangefinders back in the 1940s and 1950s, but Leica is the best-known brand for both film and digital rangefinders today.  A Leica M9 digital rangefinder camera. Although equipped with the latest digital technology, this camera is fully compatible with Leica M lenses made since 1954.

What’s not covered in this book Medium format and large format camera systems are not covered. These are large film or digital cameras designed for professional or artistic use, made by companies such as Hasselblad, Mamiya, Pentax, and Phase One.  A classic Hasselblad 500 series camera. Medium format film cameras such as this date back to the 1950s, and specially modified Hasselblads were famously used in space by NASA. In fact, twelve cameras from Apollo missions still remain on the moon’s surface.

This book is also not an engineering textbook. It’s about learning to be a more skilled driver, but it doesn’t teach you how to build cars.

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W H AT’S N O T C O V E R E D I N T H I S B O O K

CHAPTER 1

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1

A brief history of optics

1.1 The science of light At its simplest, photography is about recording waves of light and creating two-dimensional pictures. And fortunately, light behaves in very predictable and reliable ways—at least in a photographic context. Over the centuries the science of optics and the technology of manufacturing have been developed and refined, resulting in the lenses we see today. This chapter outlines some of the basic historical discoveries that made optical technology possible.

1.2 The path to the lens It all starts with light—and the ability of glass to bend it. In short, two strands of human knowledge had to come together: a working set of theories to describe how light actually functions and the technical ability to make and shape glass objects. Lens-making technology dates back thousands of years. Shaped rock crystal lenses were made in ancient Egypt and Mesopotamia, but there is only fleeting and tantalizing evidence that they were used for much more than decorative purposes until roughly the time of the ancient Greeks, when simple magnifying lenses are definitely known to have been made. ▲ The Nimrud lens, made in Assyria (present-day Iraq) around 950 BCE. It’s unknown if it had any optical purposes or was purely decorative. The rock crystal is crudely shaped, so I personally doubt it would have been a very useful tool. The British Museum, London, England.

Optical theory As for the science, it actually took quite a while for humans to figure out what light really is and how it works. And some early theories were frankly very strange by modern standards. For example, the Greek philosopher Plato (about 428–348 BCE) and the Roman physician Galen (about 129– 216) both maintained that human eyes emit special rays that allow us to see. Oddly this “extramission” theory of light never quite explained convincingly why we can’t see in the dark. Perhaps the first person to come up with a consistent and modern theory of light was the Arab or Persian polymath Abu¯ ʿAlı¯ al-H.asan ibn al-H.asan ibn al-Haytham al-Bas.rı¯ (965–1040 or so). He’s best known concisely in the West as Alhazen or al-Haytham. al-Haytham correctly realized that light is emitted by light-producing objects, such as the sun or a flame, and travels in straight lines. It then either enters the human eye directly or is reflected off various surfaces first. The eye (or an artificial substitute, such as a camera) is a passive detector of light, not an active emitter of it.

 A Latin translation of al-Haytham’s Kitab al-Manazir (Book of Optics), originally written from about 1011 to 1021, describes diffraction, refraction, spherical aberration, and a host of other optical principles. This 1572 book may be the first printed edition of al-Haytham’s work after centuries of handwritten translations and is shown here courtesy the Royal Society, London, England.

While largely forgotten by his contemporaries, al-Haytham’s ideas were translated into Latin and eventually took root in Europe. By 1267 English friar Roger Bacon (1214–1294) was writing about optical theory, relying both on his own observations and on the work of others, including al-Haytham. Some centuries later, German mathematician and astronomer Johannes Kepler (1571–1630) published Astronomiæ Pars Optica in 1604, thus establishing the groundwork for modern optics and an accurate model of human vision. Another milestone in the scientific revolution was the publication of Opticks in 1704 by English physicist and mathematician Isaac Newton (1642–1727). This work described many optical phenomena, such as diffraction and dispersion.  A first edition of Newton’s Opticks, in which he discusses the importance of firsthand observation. From the collection of the Royal Society, London, England.

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▲ “… in the beginning of the Year 1666 (at which time I applyed my self to

However, Newton espoused a “corpuscular” theory of light that, while presaging aspects of Albert Einstein’s notion of the photon, was eventually demolished by the theory of light as a wave, originated by Dutch physicist Christiaan Huygens (1629–95). Wave-based optics eventually led to the very successful mathematical models of the nineteenth century that made lens design possible. Today we understand light to be just one form of energy known as electromagnetic (EM) radiation. And it’s critically important because, unlike other forms of EM energy, such as radio waves or X-rays, we can see it with our eyes.

the grinding of Optick glasses of other figures than Spherical,) I procured me

Glassmaking

a Triangular glass-Prisme, to try therewith the celebrated Phænomena of Colours.” – Isaac Newton

 Replica reading stone from the collection of the Zeiss Optical Museum, Oberkochen, Germany.

The first optical use of glass was, of course, the development of corrective lenses for human vision. The ancient Greeks are known to have used simple lenses to help perform detailed tasks. And wealthy medieval scholars sometimes used thick hemispherical glass or crystal domes as so-called “reading stones” to magnify text.

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1.2 T H E PAT H T O T H E L E N S

But it wasn’t until the 1400s and 1500s that glassmaking for practical and decorative applications became highly developed. Key inventions included Venetian “cristallo” glass and English lead glass. These very pure materials helped enable the European optical breakthroughs of the 1600s. Thin glass lenses were devised, resulting in spectacles to assist both reading and distance viewing. Dutch philosopher Baruch de Spinoza (1632–77), for example, earned a good living grinding lenses when he wasn’t speculating about the nature of the universe.

▲ A modern-day craftsman transforms a lump of molten glass

▲ Sixteenth or seventeenth century reading glass and carrying

into a decorative sculpture. Murano, Venice, Italy.

case. Zeiss Optical Museum, Oberkochen, Germany.

With the invention of the telescope and the microscope, optics took people into very different directions of scale. By the early 1600s, Italian scientist Galileo Galilei (1564–1642) had documented the moons of Jupiter and other heavenly bodies. And Dutch microbiologist Antoni van Leeuwenhoek (1632–1723), constructing tiny microscopes by the mid to late 1600s, discovered the tiny “animalcules” (i.e., protozoa or microorganisms) that reside in a drop of pond water.

The camera Oddly enough, the first conceptual “cameras,” which can be dated back to China in the fourth century BCE, lacked both lenses and film. They were simply darkened rooms or boxes equipped with tiny pinholes. Such pinhole boxes later became popular with European artists from the 1500s to 1800s as tools to aid drawing in proper perspective. These cameras exploited the fact that light passing through a pinhole (see section 9.9) or glass lens can be projected onto a flat screen in a darkened box or chamber for viewing. This is the origin of the modern English word, in fact, as Camera obscura is Latin for dark chamber.

▲ These strange looking devices are Leeuwenhoek’s original handmade microscopes. Of the hundreds he built during his lifetime, only a handful survive today. The lenses are tiny glass spheres located at the center of each handheld tool. The Museum Boerhaave for the History of Science and Medicine, Leiden, Netherlands.

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▲ For millennia people have noticed that light cast by small gaps

▲ An experimental camera obscura used in the 1830s by

or holes, such as the tiny gap between crossed fingers, will take

French inventor Louis Daguerre to develop the Daguerreo-

on the shape of the sun during solar eclipses. This is the same

type, the first workable photographic process. It consisted

principle that makes pinhole cameras possible. Annular eclipse

of a pair of nested wooden boxes that can be moved back

in Tamerza, Tunisia, 2005.

and forth like a drawer in order to focus. From the collection of the Musée des Arts et Métiers, Paris, France.

 It may look like a model rocketship from a 1940s movie serial, but this amazing device is actually a century older. This is a “Daguerreotyp-Apparat zum Portraitiren,” or Daguerreotype Apparatus for Portraiture, made by Voigtländer in Vienna in 1840 or 1841. As a measure of how early it is, remember that Daguerre announced the first workable photographic process to the world in 1839. The lens, designed mathematically by Josef Petzval (see section 1.3), was mounted on the right side, and was covered with a cap which doubled as a shutter. Focusing was done by turning the small knob. Round metal Daguerreotype plates were put into the camera on the left side of the cone. From the Zeiss Optical Museum collection. Oberkochen, Germany.

Photography In the 1820s and 1830s, French pioneers Nicéphore Niépce (1765–1833) and Louis Daguerre (1787–1851) invented chemical methods for recording images permanently on metal plates, and photography truly began. The key elements of traditional photography—dark boxes (cameras), light-sensitive material (plates or film), and light modifiers (lenses)—had come together. For over 150 years these were the fundamental ingredients of image recording.

 A mid-twentieth-century film camera: a folding Kinax II made in France in the late 1940s. This is actually my father’s first camera.

Considerable research was done in the 1960s and 1970s into electronic imaging—the charge-coupled device (CCD) image sensor chip was devised in 1969, for example. But it wasn’t until the 1980s that workable electronic still image-capture devices were introduced. By the late 1990s, digital cameras were rapidly replacing chemical photographic imaging.

▲ The first commercially available digital SLR was the 1991 Kodak DCS (Digital Camera System). It was a stock Nikon F3 camera, with a 1.3 megapixel chip and handgrip bolted on. The camera itself was compact enough, but you also had the huge lunchbox-sized DSU (digital storage unit) containing batteries, voluminous 200 MB hard drive, and preview screen, which had to be tethered to the camera. Only well-heeled news agencies, which valued the ability of the camera to send digital shots down a phone line in record time, could justify the expense and inconvenience of this early proof of concept device.

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A B R I E F H I S T O R Y O F O P T IC S

 This photo may look simulated, but it’s the real thing. A mere two decades after the Kodak DCS, laptops and mobile phones sport incredibly tiny digital cameras such as this.

Today film is sadly nearing mass-market extinction, but even the latest and most sophisticated digital cameras employ lens technology based on discoveries dating back centuries.

1.3 Geometrical optics Modern lens design is a very complex and esoteric field and is heavily dependent upon mathematics. The earliest lens makers worked intuitively and pragmatically, testing lens after lens to see what gave the best results. They discovered that certain arrangements of lens types produced sharper images than others, thus creating a family of basic lens designs still in use today.  French opticians Vincent (1770– 1841) and Charles (1804–59) Chevalier, father and son, accidentally became the world’s first photographic lens makers when their meniscus designs were used by Nicéphore Niépce to take the first photograph in 1826. Charles later teamed up with Daguerre to make the first purpose-designed camera lenses. This is a Chevalier lens from the 1840s “Le Photographe” camera. Musée des Arts et Métiers. Paris, France.

But by the mid-1800s, particularly in Germany, people started to devise practical mathematical equations to predict the way that lenses bend light. These formulas made it possible to calculate the theoretical behavior of various optical designs before they were committed to actual lens grinding and physical testing. Ernst Abbe (1840–1905) at optical manufacturer Carl Zeiss was particularly instrumental in establishing the framework for modern computational optics. Performing the mathematical calculations was hugely time-consuming in the days before computers, and teams of mathematicians were employed to perform laborious trigonometric and logarithmic calculations on paper. The Petzval lens design of 1840 (used in the Voigtländer camera shown on page 14), for example, took nearly a dozen men several months to calculate. The rise of digital computing dramatically sped up the process and ushered in an age of complex computer models. Today, sophisticated software, advanced forms of glass, and modern automated manufacturing make all kinds of complex lenses possible.  LensForge, a computer modeling program for advanced optics, shows how rays of light will pass through a six-element “double-Gaussian” camera lens. The number crunching behind this simple diagram would have taken a mathematician hours to calculate.

1.4 Waves and particles Finally, physicists will note that this book discusses only the wavelike aspect of light. It doesn’t really deal with the strange dual nature of light, which can also be seen as little particles of energy called photons. This is because from the perspective of a humble photographer, light really only behaves as rays of energy.

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1.4 W A V E S A N D PA R T IC L E S

CHAPTER 2

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BEN DIN G LIG H T

2

Bending light

2.1 Putting glass to work So how does a lens capture light at your bidding? Each camera lens has innate optical properties determined by its designer. Optical engineers put tremendous effort into choosing the shape, number, arrangement, material, and size of each lens component in order to produce a photographic lens with the desired imaging characteristics. This chapter describes some key optical properties.

2.2 Refraction Photographic lenses must take light coming in from a scene and then narrow it down precisely to a tiny piece of film or electronics inside the camera. A physical phenomenon known as refraction explains how this works. Refraction simply means that light, which normally travels through space in dead straight lines, can change course when it passes through one transparent material to another. A classic example of refraction is demonstrated by this spoon in a glass of water. When the spoon is viewed from the side of the glass, it appears to be broken. This isn’t because of the curvature of the glass or anything— it’s because light traveling through water changes direction slightly upon ▲ Refraction is demonstrated by this hitting air. Amazingly, refraction ocspoon in a glass of water. curs because light, instead of always traveling at the famous speed of light, actually slows down when it’s not in a vacuum. Different materials, even transparent substances like glass or water, slow light by differing amounts. Lenses employ the same refractive principle as this glass of water. Pieces of incredibly pure glass (and occasionally plastic or crystal) are carefully cut, shaped, and polished in order to bend light in very specific and accurate ways.

GLASS AIR

▲ Refraction of light.

2.3 What is a lens? The term lens is sometimes a bit confusing because the word can refer to a single rounded piece of optical glass or it can refer to an entire barrelshaped device that fits onto the end of a camera and contains numerous glass discs lined up in a row. From a lens designer’s point of view, however, there’s no confusion. A single lens, such as a magnifying glass or one lens from a pair of spectacles, is known as a simple lens. Conversely, a camera lens or telescope, involving many separate bits of glass, is a compound lens (not to be confused with the multifaceted compound lens of an insect eye). Each single glass piece of a compound lens is known as a lens element.

▲ A magnifying glass is nothing more than a simple lens, often with a handle, and represents the starting point in optical technology.

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 This is an actual Zeiss Vario-Sonnar 40–120mm f / 2.8 zoom that has been cut in half. While I can hear cries of anguish from collectors, as it’s a pretty rare lens for the Contarex camera, it does mean we get to see the remarkably complex interior. And this is a 1971 lens, so it doesn’t even have the computer chips, autofocus motors, or image stabilizers found in today’s lenses. From the Zeiss Optical Museum, Oberkochen, Germany.

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2.4 L E N S EL E M E N T S

2.4 Lens elements Virtually all camera lenses sold today contain multiple lens elements. This is because they must modify incoming light in very complex and subtle ways; something that a single lens element alone can’t do. Each element will have a specific shape or size, depending on what task the lens designer wants performed. Elements can be arranged together, or even glued using transparent optical cement, to form a lens group.

▲ This shot is a double exposure. The barrel was lit normally, and then the glass was illuminated in darkness with a near-ultraviolet laser. The laser caused each element to glow, making it possible to see some of the individual glass surfaces within the lens.

Modern lenses can be very complicated creatures indeed. A typical zoom lens might actually contain, say, 22 separate lens elements, carefully arranged in over a dozen groups. And that’s not even counting the electronics, motors, and precision mechanisms used to control focus and other features.

Block diagrams Lens designs are often depicted using flat block diagrams such as the one to the right. They indicate the shape, size, and position of each lens element, in cross-section, inside the lens assembly. They’re not accurate enough to serve as lens blueprints but instead provide a general graphical description. This is the block diagram for the Zeiss Vario-Sonnar lens seen on on the previous page. The reason behind the different shapes taken on by lens elements is described in chapter 8.

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2.5 Field of view The field of view, or how much of a scene the lens can take in, is the most important optical consideration to any photographer. After all, we‘ve all had experiences like the following examples:

▲ You‘re trying to take a photo of some friends in a restaurant, but you just can’t fit everybody in. You can‘t step back because there’s a wall in the way, so your friends have to squeeze in closer. In short, the field of view provided by your lens isn’t wide enough. The solution? A lens with a wider field of view gets everybody in the frame, as seen in the second image.

▲ The reverse can also happen. Let’s say you want to take a closeup portrait of a passing Canada goose. You grab your camera but end up with a whole scene featuring some distant birds. It looks nice, but isn‘t what was intended because the lens isn’t long enough. By using a longer lens you can get amazing detail on the goose’s face, as seen in the second shot.

There are three rough categories of lenses when it comes to how much of a scene they can take in: f A normal, or standard, lens takes in a field of view that seems natural to a

person. Think of normal lenses as being good for taking pictures in close proximity to a subject, like a picture of a person standing in an ordinary room (but not traditional portraits).

f A wide-angle lens can take in a large area of a scene. This can be used for

photographing sweeping panoramic landscapes or large areas of a room. f A telephoto lens (also referred to as a long lens) provides a view like using a telescope: it narrows down what can be viewed in a scene or makes a distant subject seem closer than it really is. Portrait lenses, for example, are traditionally short telephotos.  This normal view shows a path winding through the Sagano bamboo forest near Kyoto. Sagano Arashiyama, Japan. 50mm lens on a full frame camera.

NORMAL

 An extreme wide-angle view looking upwards shows the beautiful canopy of bamboo stretching overhead. 17mm lens on a full frame camera.

WIDE ANGLE  A telephoto view compresses the apparent perspective between each plant, giving the impression of a wall of bamboo canes. 200mm lens on a full frame camera.

TELEPHOTO

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2°52' vertical

BEN DIN G LIG H T

5°9' diagonal

4°18' horizontal

▲ The field of view can be described as horizontal degrees, vertical degrees, or diagonal degrees of coverage. Typically, the diagonal field of view is used. This photo of a flowering water lily in the Waterlily House, Kew Gardens, England, was taken with a 300mm lens on a 1.6x subframe camera. This accounts for its very narrow field of view.

One might think that lenses would be described by the number of degrees of view possible. So a really wide lens might take in, say, 120 degrees of a scene, while a telephoto might take in only 10 degrees. Such a view could be calculated by taking a simple protractor from a school geometry set and measuring how much of the scene, from edge to edge, is visible. But for important technical and historical reasons, the field of view of a lens is usually measured by something a bit more obscure—the focal length.

2.6 Focal length Every lens has an optical property called the focal length, which is measured in millimeters. The focal length is key to how much of a scene a lens can view. If a lens has a very short focal length, then it’s a wide angle lens. A lens with a really long focal length is a telephoto lens. So why is the focal length used rather than the angle of view? The amount of a scene that a lens can view, assuming the lens is focusing on infinity, actually depends on two basic factors: f The focal length of the lens, which determines the amount of the scene

projected onto the image area f The size of the image area: the film or digital sensor chip And since the image area is a property of the camera and not the lens, it won’t be marked on the lens. WHY ARE CERTAIN FOCAL LENGTHS POPULAR? The answer is due mostly to tradition and convenience. There’s no real technical reason why lenses have to be, say, 28mm, 50mm, or 85mm. And some companies do buck the trends. For example, Pentax Limited lenses have unorthodox focal lengths like 40mm, 43mm, and 77mm. But for the sake of convenience, most makers tend to produce lenses with similar popular focal lengths.

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 A British-built Austin Mini parked on a Paris street. By standing close to the car and using a wide-angle lens I was able to get the roof of the vehicle to dominate the foreground of the shot. Paris, France. 17mm full frame. f / 10, 1/200 sec. ISO 100.

 A very long telephoto lens makes the distant moon seem very close to the prosaic sublunary scene below. Earthshine, the reflected light of the Earth on the dark side of the crescent moon, is just visible. Death Valley National Park, CA, USA. 280mm full frame. f / 5.6, 0.8 sec. ISO 800.

▲ Pentax has always enjoyed being different. Its standard prime lens has a focal length of 55mm, and not 50mm like almost every other manufacturer.

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400mm / 6° 300mm / 8°

The focal length of a lens isn’t the same thing as its physical length. Very long telephoto lenses tend to be physically longer, but at shorter focal lengths it’s not such a straightforward relationship.

200mm / 12°

105mm / 23°

2.7 But what is focal length, really?

80mm / 30°

50mm / 47°

35mm / 63°

28mm / 75°

Most photographers don’t know or care about the technical definition of focal length because, honestly, it doesn’t help you take photos. The focal length is simply a numeric value that describes the coverage of a lens, and with time you learn what focal length values are associated with what fields of view. If you want to explore the topic further, I have a more technical description later on in this book (see section 8.2).

24mm / 84° 20mm / 94° 17mm / 104° 16mm fisheye / 180°

▲ This diagram shows the amount of cover-

2.8 Prime or zoom: adjustable focal lengths Many lenses, known as prime or fixed focal length lenses, have a focal length that can’t be changed. This is rather like the human eye. Unless we employ supplemental lenses in the form of a telescope, for example, we can’t zoom in to see faraway details.

age, in terms of degrees of diagonal field of view, for a variety of common lens focal lengths. The diagram assumes a 35mm film camera or full-frame digital SLR is being used.

 If your camera has a prime lens, you need to physically walk around to change the field of view.

For photographers, fixed focal lengths can be a bit inconvenient or can prevent certain effects. For example, sometimes it’s easy to move forward or back to take in less or more of a scene. But other times it can be dangerous or impossible—if you have to back off a cliff or into moving traffic, for example. One solution is to pack a bag with lenses of different focal lengths and swap them out as needed. Nature photographers who work at a slow pace and carry lots of gear may take this approach. But for many of us that’s a plain hassle.

 Four primes: 28mm, 50mm, 85mm, and 135mm lenses. All could be replaced, at least in terms of focal length coverage, with a single zoom lens with a focal length range of at least 28mm to 135mm.

Another solution is the zoom lens, a lens with an adjustable focal length. With a simple adjustment you can go from wide to narrow in an instant. If you can’t fit all your friends in the picture, for example, you just rotate the zoom ring on the lens until they’re all in there. Or if that bird is too far away, you rotate it the other way to zoom in closer. IN AND OUT Adjusting a zoom lens to a longer focal length for a narrower field of view is known as zooming in. Adjusting to a shorter focal length for a wider field of view is known as zooming out.

Note one common misconception: a lot of people think zoom lenses are used for taking photos of distant objects. That’s actually a telephoto lens.

Why primes? Zooms are so convenient that the obvious question arises: why do primes exist at all? Why aren’t all lenses zooms? The reason is that adjustable focal lengths bring certain optical compromises. It’s simply more complicated to construct a zoom than a prime, and zooms usually contain more pieces of glass. If you want the sharpest, most crisp images possible, then a high quality prime lens can offer better pictures than many zooms. Low-light photography also benefits because it’s much harder to build a zoom lens that lets in as much light as a prime. And zooms tend to be larger and heavier than primes.

▲ A Canon 50mm 1.8 lens (left) has only six lens elements and a very simple, inexpensive design. The Canon 24–105 4L IS USM (right), however, has three times as many elements and is much more complex. Its size, weight, and price go up accordingly.

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Some crusty old photographers also argue that using prime lenses is very important for novice photographers because it forces them to learn about the importance of focal lengths and perspective (though to be honest, this argument sounds a bit “if it was inconvenient enough for me it’s good enough for you” to me).

Lens choice and compromises ▲ “Pancake” lenses are very thin and flat lenses, and are almost always primes. This Nikon 45mm pancake is so thin that its clear protective filter (52mm in diameter) forms a significant part of its height.

Lens construction is thus always about trade-offs. You may want a lens that’s small and lightweight, has zoom capabilities, lets in lots of light, is really sharp, has high contrast, doesn’t distort the image, and is cheap. But in real life, you can get only some of those properties in one lens. Sadly, it’s impossible to get all of them at once. Most amateurs on a budget choose the flexibility of low-cost zoom lenses over picture quality as their compromise. Some advanced amateurs choose the higher picture quality of affordable primes as theirs, despite the inconvenience. And many professionals select heavy and expensive highend zooms as theirs. The best choice for you depends on your priorities.

 From left to right: a low-cost zoom, an affordable prime, and a high-end zoom.

2.9 The 35mm focal length equivalent You’ve probably noticed a lot of lenses described in terms of their 35mm focal length. What does this mean? This doesn’t refer to a focal length of 35mm but to a type of film. The most successful film format ever is 35mm film—strips that are 35 millimeters in width and rolled into cylindrical canisters, as shown to the left. Photographers have used cameras with image areas exactly 24mm tall by 36mm wide since the 1930s. This extremely popular image area led to a common understanding among photographers as to the effect of focal lengths. Everyone knew that

28mm was a mild wide-angle lens, say, or that 200mm was a moderately long telephoto. Focal length numbers became a simple shorthand for field of view. But it’s important to remember that these familiar associations between specific focal lengths and coverage areas are only true when 35mm film is used.1 Different relationships hold with different sizes of film or image sensors. Still, it was a useful convention for many decades since 35mm SLRs were the only affordable cameras with interchangeable lenses on the market.

2.10

Digital versus film: the cropping factor

Things became more complex with the widespread use of interchangeable lens cameras that don’t use 35mm film. A digital camera with a tiny sensor will cover less of a scene than a 35mm film camera would, given the same lens. Suddenly, this well-understood shorthand—of a certain focal length lens covering a certain area—became confusing.

While the focal length of a lens is a critical factor in determining the field of view, it’s definitely not the only one. As mentioned earlier, the physical dimensions of the film or sensor are essential as well. To illustrate this point, imagine a photo printed onto a big piece of paper. Now imagine taking a pair of scissors and cutting off a bunch of paper around the edges, resulting in a smaller picture. The same identical lens, or same focal length, was used to take each shot. But the first picture takes in a lot more of the scene than the second, cropped, shot. 1 I’m ignoring half-frame 35mm cameras, like the Olympus PEN of the 1960s, here. These used 35mm film but with reduced image areas, resulting in different focal length relationships.

▲ The camera on the left has a “full frame” image sensor that’s the same size as 35mm film: 36 × 24 mm. The camera on the right has a “subframe” sensor that’s about 22 × 15 mm in size.

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It’s exactly the same thing with cameras. A lens, when used on a camera with a big image sensor, might function as a wide-angle lens, taking in lots of a scene. But the same lens, when fastened to a different camera with a smaller digital sensor, might seem considerably less wide. This is known as a cropping factor.

▲ This photo of Canada Place in Vancouver demonstrates how using a camera with a small-sized or cropped sensor is like trimming down a photo.

▲ The unbelievably ornate dome of Siena’s Duomo

▲ The same 17mm lens on a cropped-sensor camera loses

cathedral, Siena, Italy. A 17mm wide-angle lens on a full-

a lot of information around the edges. You’d need an 11mm

frame camera takes in a broad and dramatic view. Siena,

lens to take in the same scene.

Italy. 17mm, full frame. f / 6.3, 1 sec. ISO 200.

 Of course, it’s not all bad. A crop frame camera also increases the reach of a telephoto lens, letting you take photos of objects farther away. Here a 300mm lens was used with a 1.6x camera, giving the same field of view as a 480mm lens on a 35mm camera. This extremely long lens reveals distant “fairy chimneys” one stormy sunset. Göreme, Cappadocia, Turkey.

Focal length equivalence Some lens makers describe their lenses as having a certain “focal length equivalence.” This arguably confuses things because the focal length doesn’t actually change at all. Instead, because of the cropping factor, the field of view will be different if a small sensor is employed. Such cameras are commonly known as subframe cameras, versus full-frame SLRs, which have the same sensor size as 35mm film.  This lens, designed for a Micro Four Thirds subframe camera, actually has two sets of focal lengths printed on it: the real focal-length range and, in larger type, the full-frame focal-length range that would yield the same coverage area. To me this seems like a great way to confuse customers.

The cropping factor The size of a digital sensor, when compared to 35mm film, is sometimes expressed as a number, such as 1.5x. The idea behind this “focal length multiplier” is that you take the focal length of the lens, multiply it by the cropping factor, and wind up with the focal length of the same coverage as when used with 35mm film. Consider this traditional diagram of various popular sensor sizes and their cropping factors relative to 35mm film.

▲ This Panasonic Lumix camera has a small Micro Four Thirds sensor, meaning it has a cropping factor of about 2x compared to 35mm film.

 These boxes depict actual sensor sizes Full-frame or 35mm film camera

Black

1x

Canon EOS 1D to 1D IV

Light blue

1.3x

Nikon DX, Sony Alpha, Samsung NX

Yellow

1.5x

Canon EOS EF-S

Red

1.6x

Four Thirds / Micro Four Thirds

Green

2x (approx)

Nikon 1/CX

Purple

2.7x

Pentax Q / many point-and-shoots

White

5.5x (approx)

Of course, when actually using a camera you don’t need to do all this arithmetic in your head. What you see through the viewfinder or on the preview screen is what you’ll get. These cropping factors are only important when comparing the field of a view of a lens on a full-frame camera versus the same lens on a subframe camera.

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2.11

APS-C

The Advanced Photo System (APS) was a film format introduced in 1996. The idea was to create user-friendly and compact cameras, but the film was more expensive than 35mm and offered few advantages. APS was finally killed by the rise of digital. ▲ APS film cartridges.

 Sony E-mount cameras, such as this NEX model, employ sensors roughly APS-C in size.

However, one aspect of APS still lives on in terms of digital sensor naming. APS supported three film frame sizes, of which APS-C was most popular. The 1.5x and 1.6x subframe digital SLR cameras employ digital chips of roughly the same size as a frame of APS-C film, which was 25.1 × 16.7 mm.

2.12

▲ Medium-format (MF) film.

Medium format

The discussion so far has been about 35mm film and equivalent image sensor sizes, but what about other types of film? Medium-format (MF) film is usually 6 centimeters wide and offers much higher image quality than 35mm film. Hasselblad, Mamiya, Rollei, and Pentax are well-known camera makers in this market. MF-sized digital cameras, and add-on camera backs for film cameras, are so costly that they’re restricted mainly to commercial and fine art photography. Phase One and the major MF camera makers all make such products. Common digital sensors are 48 × 36 mm or 54 × 40 mm in size, compared to MF film frames, which can be 56 × 42 mm (645), 56 × 56 mm (6 × 6), or 56 × 70 mm (6 × 7) in size, so the crop factor applies here too. There are also large-format film cameras, which usually employ massive sheets of film 4 × 5 inches or 8 × 10 inches in size. There’s even the staggeringly huge 20 × 24 inch Polaroid format, though only six of the original filing cabinet-sized cameras still exist. Medium and large formats are not the primary focus of this book, however. So any references to full frame or subframe in this book are relative to 35mm film only.

2.13

Focal length examples

It can be difficult to understand the relationship between the focal length and the field of view of a scene, so the next two pages contain a series of comparative shots. They were all taken from the same location in Vernazza, Cinque Terre, Italy. Everything used for the shots was identical except for the focal length used. The first two shots were taken with circular and full-frame fisheye lenses (see section 5.3), respectively. The rest were taken with normal “rectilinear” lenses (see section 8.12). Each shot is marked with the focal length required to take in the scene, given a full-frame 35mm camera; a 1.5x crop camera like a Nikon DX, Pentax digital, or Sony Alpha APS-C model; or a 1.6x crop camera like a Canon EF-S model.

2.14

Image circles

Projectors shine images onto screens in darkened rooms or movie theaters. Cameras work in a similar way. They take light from the outside world, pass it through a lens, then project the final image onto the film or digital image sensor inside the darkened chamber of the camera body. This projected image has a circular shape with most lenses and so is called the image circle. The projected image circle has to be big enough to cover the whole imaging area comfortably or else black areas can appear in the corners. A coverage problem can occur when a lens with an image circle designed for a small image area is used with a larger image area. For example, Nikon subframe DX lenses have the same physical lens mount as full-frame FX lenses. So if you attach a DX lens to a camera with full-frame capabilities, you can end up with the coverage problem. It does depend on the camera and lens, though. Nikon FX cameras can detect compatible DX lenses, and can automatically crop the image down to avoid the black areas if set to do so, but they aren’t able to do this for all lenses.

 This can be what you get if you put a subframe lens on a full-frame camera that doesn’t crop automatically. The Capitol, Dougga, Tunisia.

Focal plane Lens

Film or sensor

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This chart lists the focal lengths needed to achieve the fields of view depicted. The focal lengths given are for full-frame cameras (35mm equivalent), 1.5x crop cameras, and 1.6x crop cameras.

180° vertical, fisheye

180° diagonal, fisheye

104° diagonal, extreme wide angle

Full-frame: 8mm circular fisheye

Full-frame: 15mm full-frame fisheye

Full-frame: 17mm

1.5x crop: 4.5mm circular fisheye

1.5x crop: 13mm full-frame fisheye

1.5x crop: 11mm

1.6x crop: 4.5mm circular fisheye

1.6x crop: 13mm full-frame fisheye

1.6x crop: 11mm

63° diagonal, wide angle

57° diagonal, standard

47° diagonal, standard

Full-frame: 35mm

Full-frame: 40mm

Full-frame: 50mm

1.5x crop: 23mm

1.5x crop: 27mm

1.5x crop: 33mm

1.6x crop: 22mm

1.6x crop: 25mm

1.6x crop: 31mm

23° diagonal, telephoto

17° diagonal, telephoto

12° diagonal, telephoto

Full-frame: 105mm

Full-frame: 140mm

Full-frame: 200mm

1.5x crop: 70mm

1.5x crop: 93mm

1.5x crop: 133mm

1.6x crop: 66mm

1.6x crop: 88mm

1.6x crop: 125mm

94° diagonal, extreme wide angle

84° diagonal, wide angle

75° diagonal, wide angle

Full-frame: 20mm

Full-frame: 24mm

Full-frame: 28mm

1.5x crop: 13mm

1.5x crop: 16mm

1.5x crop: 19mm

1.6x crop: 12mm

1.6x crop: 15mm

1.6x crop: 18mm

37° diagonal, short telephoto

30° diagonal, short telephoto

27° diagonal, telephoto

Full-frame: 65mm

Full-frame: 80mm

Full-frame: 90mm

1.5x crop: 43mm

1.5x crop: 53mm

1.5x crop: 60mm

1.6x crop: 41mm

1.6x crop: 50mm

1.6x crop: 56mm

9° diagonal, telephoto

8° diagonal, extreme telephoto

6° diagonal, extreme telephoto

Full-frame: 280mm

Full-frame: 300mm

Full-frame: 400mm

1.5x crop: 187mm

1.5x crop: 200mm

1.5x crop: 267mm

1.6x crop: 175mm

1.6x crop: 188mm

1.6x crop: 250mm

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Canon took a different approach with its EF-S line of subframe lenses. While EF-S cameras can also accept EF lenses, EF-S lenses can’t physically mate with EF-only full-frame cameras, thereby avoiding this problem.  A Canon EF lens (left) and an EF-S lens (right). The EF-S lens has an additional projection at the end, so it cannot be used with an EF-only lens mount. Note that this particular EF-S lens has a plastic mount, though many EF-S lenses have metal mounts.

2.15

All about apertures

If you’re ever able to see the eyes of a person in near darkness, you’ll see a huge dilated pupil ringed with a tiny bit of iris. Yet the same eye in bright sunlight will be mostly iris with a tiny speck of black pupil. The iris, or colored part, of the eye is a muscular mechanism that can open up to let in lots of light or close down to restrict the amount of light coming in. Most camera lenses have a surprisingly similar mechanism, though one rather less beautiful than an iris. Lenses have diaphragms, which can open or close to create large or small openings called apertures. The size of the aperture controls how much light enters the lens and strikes the film or sensor. The aperture is not used to determine the length of an exposure of a photo by blocking light—that’s the shutter’s job. The aperture is about quantity, not duration. This may seem a bit odd. After all, why go to all that trouble building a lens capable of sending every possible photon of light through, then stick a mechanism in the middle to block light? There are several reasons: f Just as with the human eye, if your scene is too bright you need some

▲ The diaphragm mechanism is like the iris, and the aperture is like the pupil.

way of restricting the amount of light flooding in. You can do this by setting a fast shutter time, adjusting the camera’s ISO setting (or using slower film), or sticking a dark filter over the lens. But a simple adjustable aperture is by far the most convenient way to do it. f Many optical problems with lenses can be minimized by making the aperture smaller. Most lenses, in fact, tend to be slightly sharper when the aperture is set to a middle setting like f / 8 or f / 11. Shooting with a lens wide open maximizes low-light capabilities but also tends to decrease performance. See chapter 8 for more about aberrations. f The amount of a scene that’s in focus is affected by the aperture setting. This is known as depth of field, and section 2.21 is dedicated to that.

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SHUTTERS Though uncommon, a handful of cameras actually use the same mechanism as both lens diaphragm and shutter. The Pentax Auto 110 SLR of the 1970s is one such camera. Most SLRs have shutter mechanisms, called focal plane shutters, built right into the camera body. However, some medium- and large-format cameras position a shutter inside the lens, which is known oddly as “between the lens.” Finally, some digital cameras lack shutter mechanisms altogether and just turn the sensor on and off. This is known as an “electronic shutter.”

2.16

F-stops

The very first lenses lacked easily adjustable apertures. But in the mid 1800s British astronomer John Waterhouse (1806–1879) created an invention now named after him—the Waterhouse stop. These were simple metal plates that were inserted into slots in the lens barrel. Each plate had a different sized hole. Today’s self-contained diaphragms are more convenient than a bag of metal plates, but the settings are still known as stops. More accurately, a lens aperture is known as its f-stop (the f is traditionally italicized for good looks). Apertures are described numerically, with small numbers referring to large apertures (a big hole = lots of light coming in) and large numbers referring to small apertures. This system may seem very weird, but it has a technical logic behind it. Basically, each f-stop is actually a ratio. This is why lens aperture settings are often written as, for example, 1:1.8 or 1:5.6. And the ratio is as follows: the focal length of the lens (hence the f) divided by the aperture diameter Here’s the traditional sequence of f-stops found on most 35mm cameras and digital SLRs: 1.0 1.4 2.0 2.8 4.0 5.6 8.0 11 16 22 32.

▲ This Voigtländer lens from the 1850s is equipped with slot for Waterhouse stops. A stop’s rectangular tab can be seen protruding from the side of this lens.

STOPPING DOWN “Stopping down” a lens refers to adjusting the lens from a large aperture setting (say, f / 4) to a smaller one (say, f / 11). The reverse is called “opening up,” never stopping up.

f/1.4

f/2

f/2.8

f/4

f/5.6

f/8

f/11

f/16

f/22

Not every aperture value listed here is possible with each given lens. This is just a range of possible apertures. A traditional point of confusion is that the aperture size gets smaller as the number gets bigger. This is a bit like fractions, which get smaller as the denominator gets bigger. For example, 1/2 is bigger than 1/32.

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T-STOPS f-stops aren’t the only way to describe how much light passes through a lens. The apertures for lenses used in moviemaking are described in terms of Tstops. The T stands for transmission. Since different lenses pass different amounts of light (number and type of lens elements, type of coating, etc.), each cinema lens (see section 8.25) is measured and calibrated at the factory. T-stops involve absolute measures of light, whereas f-stops involve relative measures of length. Knowing the light-absorbing characteristics of each lens is particularly important to cinematographers when multiple cameras with different lenses are used to record the same scene simultaneously.

A mathematical diversion But where does this odd range of numbers come from? Why is there this seemingly random set of aperture settings? Why isn’t it just a sequence like 1, 2, and 3? Aperture sizes are based on the biology of the human eye. We don’t see changes in brightness in a linear fashion (1, 2, 3, 4). We actually sense changes in light brightness—and sound levels for that matter—in a roughly logarithmic fashion (2, 4, 8, 16). The aperture range represents a halving of brightness for each decrease by one stop. To halve the brightness, you halve the area of the aperture opening. And that means you multiply the diameter of the aperture circle by the square root of 2. So you start with a maximum theoretical aperture of f / 1 and multiply each f-stop by the square root of 2, which is about 1.4. The numbers are then rounded up for convenience, and you get the scale listed earlier. HALF AND THIRD STOPS There are two common ways of subdividing the number of stops on a lens: half and third stops. Which is better is simply a matter of preference, and many cameras allow you to choose. Since these settings apply to shutter speed increments as well, they’re sometimes referred to as exposure values (EVs) rather than stops.

2.17

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Maximum apertures

Another key property of a lens is the largest aperture setting that it’s capable of. This value, the maximum aperture, is important for a number of reasons.

Why lenses with large maximum apertures are desirable and expensive If you’ve ever priced out lenses with similar specifications except for the maximum aperture, you’ll notice a huge difference in cost. Even seemingly small differences in maximum aperture can result in massive price disparities. For example, the list price of the Canon 85mm 1.2L is about five times that of the Canon 85mm 1.8. There are a number of reasons for this. f At large apertures a small difference in numerical values can actually

represent a big difference in actual aperture. f / 1.2 (right) doesn’t sound like it’s much bigger than f / 1.8 (left), but as this photograph shows, there’s a noticeable increase in light-gathering capacity. f It’s often necessary to employ exotic glass or complex manufacturing techniques to produce a very “fast” lens (see section 2.18). f Fast lenses are typically marketed to experienced photographers, which means that they tend to be built to a high standard. They may have sturdy metal barrels, weatherproofing, advanced electronic features, and other features that add to the cost. They are sold in low volumes, though usually with high profit margins. There is one exception here: standard primes. It’s not that difficult to build a fairly fast lens when standard focal lengths are involved, especially if the lens is a prime lens. For this reason, 50mm primes are commonly available as f / 1.4 and f / 1.8 lenses, and they can be fairly cheap (see section 5.4). With modest increases in cost 28mm and 85mm lenses can also be available as f / 1.8 models. But anything longer or shorter than that tends to involve big price jumps.

Constant versus variable aperture zooms There are two basic types of zoom lenses when it comes to maximum apertures. Most affordable zooms have variable apertures, meaning they have a larger maximum aperture when at the short end of the range than at the telephoto end.

▲ Two Canon 85mm lenses. The left lens has a maximum aperture of f/1.8, and the right lens has a maximum aperture of f/1.2.

▲ A standard Nikon 50mm f/1.4 lens.

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▲ A consumer lens with variable maximum apertures, ranging from f/3.5 to f/4.5.

A typical consumer zoom, for example, may vary from f / 3.5 at the wide end to f / 5.6 at the long end. However, more expensive lenses may have constant apertures, which means that the maximum aperture stays the same throughout the zoom range. The most expensive zoom lenses tend to have a maximum aperture of f / 2.8 across the range (see section 2.8). A slightly less costly lens might have a maximum aperture of f / 4 across the range. Constant aperture zooms are more expensive to buy for the simple reason that they’re more expensive to make. More advanced optical engineering is required to have the same aperture range throughout. This also means that such lenses are aimed at the professional market. These should really be called constant maximum aperture and variable maximum aperture lenses, but the word maximum is usually dropped.

2.18

▲ A professional lens with a fixed maximum aperture that’s f/2.8 all the way along the focal length range.

Fast and slow lenses

These are commonly used terms—some lenses are said to be fast and others slow. While this may sound like a reference to the speed of their autofocus motors, the terms actually refer to the amount of light a lens can let in. A “fast” lens can let in lots of light when its aperture is wide open so that relatively brief, or “fast,” shutter times can be used. A prime lens with a maximum aperture setting of, say, f / 1.2 or f / 1.8 would be considered fast. A fast zoom might have a maximum aperture of f / 2.8. A “slow” lens is not able to let in as much light, thereby requiring longer, or “slower,” shutter speeds. A lens with a maximum aperture of f / 4 might be considered to be slower. Maximum f / 5.6 or f / 8 would be very slow. Lens speed matters for three basic reasons: f Fast lenses can help you take sharper photos in low-light conditions by

allowing shorter exposure times. f Since it’s more expensive to build a fast lens, such products tend to be of higher quality and pitched more to the professional market. f Fast lenses let in lots of light, meaning a brighter view in an optical viewfinder. They also improve autofocus speed. ▲ A fairly fast 50mm f/1.4 lens by

Is that lens fast or slow?

Sigma.

On 35mm or full-frame cameras, the nearer a lens focal length is to 43mm (the diagonal of the image area), the easier it is to construct as a fast lens. Thus 50mm prime lenses tend to have large maximum apertures. The wider or longer the lens gets, the more expensive it is to make it fast.

Zoom lenses are similarly affected, though the problem is even more pronounced since it’s more difficult to build a fast zoom than a fast prime. For that reason, a standard zoom with a range close to 43mm is easier to build as a fast lens than is a wide angle or telephoto zoom. And a zoom lens with a big focal length range is even less likely to be a fast lens. SPEED DEMONS There have been a handful of insanely expensive lenses that have attained f / 1 or faster. The discontinued Canon EF 50mm 1.0L was the fastest 35mm SLR lens ever, and autofocus to boot. For manual-focus rangefinders, there are the Leica Noctilux-M 50mm 0.95 ASPH and the Canon S-mount 50mm 0.95 of the 1960s. But most amazing of all was the Zeiss 50mm 0.7, originally built for NASA research and later used by director Stanley Kubrick.

▲ Kubrick was legendary for pushing the limits of technology in service of his filmmaking. In the case of his 1975 period film Barry Lyndon, Kubrick wanted interior scenes lit solely by candlelight, just as they would have been in the eighteenth century. This was considered impossible at the time, owing to the slowness of the film emulsions available. Undeterred, he located some Zeiss Planar f/0.7 still-photography lenses, from a small batch built for NASA, and had them adapted for use with a heavily altered Mitchell BNC movie camera. The resulting candlelit scenes were extremely challenging to film (see depth of field, section 2.22), but are also some of the most memorable scenes in the movie. Shown above is one of the Kubrickified Zeiss Planar lenses, along with surviving double-wick candles originally made for the film. From the Stanley Kubrick Archive, courtesy producer Jan Harlan.

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Here’s a table outlining the sort of maximum apertures you can expect for different focal lengths. Focal length

Typical aperture

Fast lens

20mm

2.8

2.8

28mm

2.8

1.8

35mm

2.0

1.8

antique all-manual lens.

 Seeing stars: aperture-induced rays around point light sources. Little Venice, London, England. 24mm full frame. f/19, 30 sec. ISO 400.

1.4

50mm

1.8

1.4

1.0–1.2

85mm

1.8

1.4

1.2

135mm

2.8

2.0

200mm

2.8

2.0

300mm

4

2.8

2.19

▲ The diaphragm mechanism from an

Very fast lens

Diaphragms

Diaphragms are thin overlapping metal or plastic blades that rotate in or out, changing the size of a hole—the aperture—at the center. The number and shape of these blades determines the physical shape of the lens aperture. An interesting effect related to the construction of the diaphragm involves stars that appear around high-contrast points, like bright light sources at night. When a lens is stopped down to a small opening, diffraction effects (see section 8.22) create little stars. Odd numbers of blades result in double the number of rays; even blades result in the same number of rays because each ray is doubled up. The roundness of the aperture also has an effect on the optical property known as bokeh (see section 9.8).

2.20

Adjusting the aperture

The method for adjusting the aperture diaphragm depends on the camera and lens used. For many years the traditional means was an adjustable ring in the lens barrel. Turn the ring one way to stop down; turn it the other way to open up. A simple mechanical linkage. However, since the introduction of Canon EOS in 1987, camera makers have been installing electric diaphragm control motors inside lenses and discontinuing the manual aperture rings. Such lenses have aperture control on the camera body itself, typically in the form of a rotating thumbwheel. These “electromagnetic diaphragms” can sometimes cause compatibility issues. In the case of Canon EOS, all EF lenses have aperture motors and all cameras have aperture control, so there’s no problem. But in the case of Nikon, for example, a G lens with no aperture ring can’t be easily used by an older film camera with no electronic aperture control. Some Pentax lenses and cameras can be similarly affected. The reverse is also true. Some newer low-cost Nikon, Pentax, and Sony DSLR cameras require a lens with an aperture motor. These cameras aren’t able to adjust the aperture setting of older lenses that lack such motors. Check your user manual for details.

2.21

▲ A typical computer-controlled diaphragm from a modern camera lens. The raised section festooned in ribbon cables is a housing for the “stepper” motor.

Wide-open metering

If you’ve ever peered into a lens, you may have noticed that the diaphragm isn’t always visible. Why is this? Most cameras do their metering with the diaphragm wide open. This also makes it easier to look through the viewfinder—things would be really dark if you happened to be using a small aperture setting. Then, when the camera’s shutter release is pressed, it rapidly stops the lens down to the predetermined aperture, takes the photo, then springs the aperture right back to the wide-open position again. This is so quick it’s nearly imperceptible.

Depth of field preview

This Canon DOF preview button ▲ (above) is an unmarked button next to the lens mount, whereas this Pentax DOF control ▼ (below) is built into the spring-loaded on/off switch by the shutter release button.

Many cameras have a way of stopping the lens down without taking a photo. This is the depth of field (DOF) preview button, often located somewhere near the lens mount. Pressing this button closes down the lens aperture to whatever setting you’ve preselected. This will result in a darkening of the view through the viewfinder if a small aperture is selected. Try this and look through the front of the lens to see the lens diaphragm mechanism springing into action. But what’s meant by the depth of field?

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2.22

Depth of field

A lens can focus at only one distance at a time. So not every part of a photo can be sharp.  The focus in this shot is on the champagne flute, and the background is quite blurred thanks to shallow depth of field. This is a useful photographic technique known as selective focus, which draws the viewer’s eye to key sections of the scene. Hotel Everland, Paris, France. 105mm full frame. f/4, 1/100 sec, ISO 100.

When thinking about focus, it can be useful to imagine a vast pane of glass located at the exact distance that the lens is focused. Everything in the final photo that’s situated at this imaginary pane is going to be sharp. And things far away from it will be blurry and out of focus in the photo. The glass pane isn’t a perfect analogy though. Objects situated at the glass will be sharp and objects further away won’t be. But what about things in between?  Of the rows of flowers, the middle row is sharp, because that’s the row the camera is focused on. However the nearer and farther flowers are very much out of focus. Keukenhof gardens, Lisse, Netherlands. 300mm 1.6x subframe. f / 5.6, 1/500 sec. ISO 100.

The answer is that there isn’t a sharp transition point between things that are in focus and things that aren’t. Instead, there’s a gradual gradient between the two. There’s no way of saying what’s truly in focus and what isn’t within that gradient. There’s a range where things are more or less acceptably in focus compared to the sharpest point. The transition between sharp and blurry is subjective. This area of acceptable focus in our photo is known as the depth of field. A photo with a narrow range of acceptable focus has a shallow or narrow depth of field. Conversely, a photo where lots of things are acceptably sharp, even objects fairly far from the plane of focus, has a deep or wide depth of field. Numerous factors determine how deep or shallow the depth of field is going to be.

Aperture and depth of field The size of the aperture is one of the main depth of field determinants. A large aperture—the lens is wide open—will result in narrower depth of field. A small aperture—the lens is stopped down—will result in a deeper depth of field.

▲ At f / 1.2, depth of field is incredibly shallow. Note how

▲ By stopping down to f / 16 we ensure that most of the

only one row of chess pieces is actually in focus.

pieces on the board are in reasonably sharp focus.

So the aperture setting and depth of field are interrelated. This can be a problem if you want to adjust one thing without affecting the other. This is also why depth of field preview (see section 2.20) can be useful; it gives you a live and immediate demonstration of what the DOF will be in the final picture, particularly useful with digital Live View.

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Image area and depth of field The size of the recording area—whether film or a digital chip—is also key to depth of field. The larger the area, the shallower the shallowest possible depth of field and vice versa.  This portrait was shot at f / 2.8, and depth of field is so shallow that although the model’s right eye is in focus, her left eye isn’t. 85mm, 1.6x subframe. f / 2.8, 1/30 sec. ISO 200.

This is one of the reasons professional portraitists with large cameras can get that beautifully razor-thin depth of field, whereas users of pointand-shoots can’t. Digital point-and-shoot cameras tend to have tiny image sensors, which is one reason everything’s sharp with these cameras. By contrast, shallow depth of field can be difficult to work with, but it can also yield fantastic photographs. The Planar lens shown in section 2.17 was incredibly difficult to use because of the vanishingly thin depth of field at f / 0.7. If you watch Kubrick’s film Barry Lyndon you’ll notice that the actors barely lean forward or back during the candlelight scenes. Had they done so they’d have gone right out of focus.

Other factors determining depth of field Numerous other factors come into play when determining depth of field: f The size of the image. A tiny photo on a website may appear to be ac-

ceptably sharp, but when printed in a large size, whole areas may appear to be out of focus. f Viewing distance. A small 4x6 print viewed close up may reveal big areas that are out of focus. But if the same print is on the wall, it may seem to be acceptably sharp.

f Distance of subject to camera. A macro or closeup photo, where the sub-

ject is extremely close to the camera, will have a very narrow depth of field. On the other hand, a telephoto shot of an object far away will have greater depth of field. Here, it’s the distance, not the focal length per se, that’s affecting depth of field. f Subjective perception. Since there’s no objective way of assessing what’s in focus and what’s not, the apparent depth of field also depends on the viewer. For further technical information on depth of field, see section 2.22.  A medium-wide aperture and the fact that both model and smoke are more or less in the same plane (and thus roughly the same distance from the camera) means that most of this shot is in focus. 50mm full frame, f/8, 1/60 sec, ISO 100.

 A wide-open aperture and a fair distance between the closest and furthest pews means that focus is restricted to just one of the carvings. Fitzalan Chapel, Arundel Castle, Arundel, England. 105mm full frame, f/2.8, 0.4 sec, ISO 100.

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CHAPTER 3

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3

Lens mechanisms

3.1 What’s in a lens? The earliest photographic lenses were simply discs of glass in metal frames or tubes. But today’s lenses are a fine blend of optics (light-focusing glass), electronics (computers and circuits), and mechanisms (rotating cylinders, electric motors), all housed in a metal or plastic barrel. This chapter discusses the electronics and mechanisms that make up a modern camera lens. These can be quite complex, as this photograph of the internal components of a single Canon 70-200 4L lens demonstrates.

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3.2 A lens that fits: lens mounts The first thing to consider is whether the lens can be physically attached to the camera at all. Lenses have mechanical connectors called lens mounts, which fasten to matching mounts on the camera. There are no universal standards for lens mounts. Each major camera maker can and often will create its own lens mount design and build a product line around it. There are several key points here: f Most lens mounts are manufacturer specific.

You can’t directly attach a Nikon lens to a Canon body or a Pentax lens to a Sony camera. f Some companies don’t make cameras but specialize in making lenses compatible with other manfacturer’s camera systems. These are thirdparty lens makers (see section 7.1). f Nearly all lenses sold today use a “bayonet” lens mount. These are rings with three or four lugs that fit into matching slots in the camera body. You then rotate the lens a partial turn to lock it in place. f Some makers build lenses that turn clockwise to lock, and others counter-clockwise. It makes little difference which direction is used, but it can be very confusing for a moment when you switch from one camera system to another. f Some older lenses for film cameras use a threaded lugless “screw mount” system in which the lens is turned several times until it’s tight. A few have “breech lock” systems that use rotating pressure rings. f Most cameras and lenses have metal lens mounts, though sturdy plastic is seen on cheaper products. f Sometimes lenses for one system can be adapted to fit a camera with a different system. This is done using an adapter ring (see section 9.2). You typically lose features though. f In addition to the physical lens mount, modern lenses have mechanical linkages for autofocus and aperture, electrical interfaces for electronic components, or both.

▲ A modern bayonet-style lens mount makes attaching and detaching an interchangeable lens simple.

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3.3 Popular lens mounts Countless lens mounts have been invented over the years. Here are some covered in this book.

Canon EF

Four Thirds

Nikon F

Pentax K

Sony Alpha

Consult Appendix A for more details on each of these and other lens mount designs.

3.4 Motors and mechanisms For most of photographic history—up until the 1980s, in fact—all cameras were either manual focus or fixed focus. Manual-focus cameras usually have a rotating ring on the lens that moves part of the lens nearer to or further from the film or sensor, thereby altering the focus. Fixed focus lenses, generally found today on dirt-cheap or disposable cameras, are fixed permanently a certain distance out; the photographer just has to point and hope.  A Kodak Portrait Brownie No. 2, made in 1929 or 1930. Literally millions of these primitive box cameras, the first point-and-shoot, were sold or given away between 1901 and 1962. Much like today’s disposable film cameras, the Box Brownies had a single-element fixed-focus lens.

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Today, however, most cameras on the market are autofocus. They contain special sensors and computers to examine the scene, and small electric motors to control the actual focus setting of the lens. SLRs typically have “phase detection” autofocus sensors located at the base of the mirror box. Mirrorless digital cameras usually don’t have separate sensors but process the image on the main sensor itself. The position and type of the autofocus motor depends on the manufacturer and model of the camera. ▲ This is the interior of a Canon EOS film SLR’s mirror box, looking forward from the back of the camera. The openings at the bottom contain the autofocus sensors. This particular camera has three sensors—two sensitive to horizontal lines, and one capable of sensing both vertical and horizontal lines (a cross sensor). The round lens above is a flash sensor.

LISTENING IN While all cameras today use light sensors, one of the earliest autofocus cameras used, bizarrely enough, sound waves. 1978’s Polaroid SX-70 Sonar OneStep (right) estimated focus distance by listening to the reflection of ultrasonic sounds, which meant it couldn’t work through glass.

Focus motors inside the camera Older autofocus film SLRs from Minolta, Nikon, and Pentax have focus motors within the camera body itself. A small mechanical linkage joins the lens and camera when the lens is attached. This has two primary advantages: First, the lenses can be smaller because they don’t need to contain a motor. Second, lens prices can theoreti-

▲ This strange looking folding device is a Polaroid SX-70 instant camera. The black plastic box with the gold disc houses the ultrasonic transmitter/receiver for its autofocus system.

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cally be lower. This in-body design has been carried on to many digital SLRs from Nikon, Pentax, and Sony.

Focus motors inside the lens

▲ The round component, which looks like a slotted flathead screwdriver head, is part of the autofocus linkage of this lens.

In 1987, Canon introduced its EOS line of cameras, taking a different approach by placing the motor inside the lens. While slightly more expensive, because every lens you buy has to have a motor in it, this approach confers some interesting advantages. First, it becomes possible for the maker to tailor an individual motor to the specific needs of each lens—you aren’t just stuck with whatever motor the camera has. A huge telephoto lens might need a totally different motor design than a wide-angle lens. In fact, it can be difficult to drive the focusing elements of a large lens using a small in-camera motor. Second, different focus motor technologies become possible. Canon took this to great commercial advantage by creating the ultrasonic focus motor (see section 3.5). Silent stepper motors (STM) for video are another lens motor technology. Most SLR makers have, since the late 1990s or so, been transitioning their cameras to an in-lens focus motor design. For this reason it’s sometimes the case that a new SLR with no focus motor is incapable of autofocusing an older lens that’s otherwise fully compatible.

3.5 Ultrasonic focus motors ▲ The autofocus mechanism from an inexpensive Canon EF lens. The silver device at the front is the autofocus motor, which drives the little train of black plastic gears. The copper vane atop the motor is part of a rotation counter.

Regular autofocus systems employ tiny cylindrical electric motors that drive a system of tiny little gears, like those from a model car or train. These are reliable, but a bit slow and a bit noisy. Ultrasonic motors, by contrast, are the pinnacle of mechanical simplicity. They use two concentric metal rings that generate a high-frequency vibration that’s inaudible to the human ear. The vibration causes one of the rings to spin, thereby rotating the lens assembly. The ring shape is why these motors have to be situated inside the lens and not the camera body. Ultrasonic motors are fast and nearly silent in operation. They usually just emit a faint whir instead of that coffee grinder whine that accompanies traditional lens motors, though cats and dogs can probably hear more.

Full-time manual focus Autofocus lenses with regular mechanical geartrains can be damaged if you force the focus ring to turn when the gears are engaged. However, lenses with true ring-shaped ultrasonic motors can be adjusted by hand for touchup manual focus without the need to disengage autofocus mode first.

Canon refers to this capability as full-time manual (FT-M), Nikon calls it “autofocus with manual override,” and Sony calls it “direct manual focus.” Most ring ultrasonic motors can simply be focused manually when the power is off, though a few “fly by wire” models can’t. While ultrasonic motors are great, note that some inexpensive lenses use micro ultrasonic motors to drive a traditional geartrain, thereby losing most of the advantages a true ring ultrasonic motor can bring. Check carefully before buying. Most lenses that lack full-time manual are probably not ring ultrasonic.

Ultrasonic trademarks The technology is marketed under many different names: f Canon: Ultrasonic Motor (USM) f Nikon: Silent Wave Motor (SWM) f Olympus: Supersonic Wave Drive (SWD) f Pentax: Silent Drive Motor (SDM) f Sigma: HyperSonic Motor (HSM) f Sony: Super Sonic Motor (SSM) f Tamron: Ultrasonic Silent Drive (USD) Note that motor types don’t affect image quality in any way. A lens with lousy optics and an ultrasonic motor still has lousy optics.

3.6 Motion blur Motion blur during an exposure is an enemy of image sharpness and a photographer’s bane. Whether the camera moves relative to the subject or the subject moves relative to the camera—or both—movement will always cause some degree of blurring. It’s a bit like touching a pencil to a piece of paper. If either pencil or paper move during contact, you get a line rather than a crisp dot (right). The solution is either to stop the motion of the pencil or paper, or tap the pencil very quickly during the motion. The same thing applies to photography, only instead of dots and lines you have either sharp or blurry photos. And likewise, if you can’t do anything about the motion of camera or subject, you can use a very short shutter time (short exposure) to minimize the blur. But let’s say that short shutter times aren’t possible, such as under lowlight conditions. Then the best bet is to put the camera on a flat surface or a tripod. After all, the best photographer in the world can hold the camera only so steady. Add coffee to the mix and all bets are off!

▲ Amazingly, these metal rings constitute a ring ultrasonic focus motor. The toothed or crenellated ring is the stator, which stays put. The smooth ring is the rotor, which turns.

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 The blurring in this shot is primarily the result of camera motion relative to the subject. This is easily seen in the closeup view of the eye, where the camera motion causes the highlight to be rendered as a line rather than a dot.

3.7 The handheld rule There’s a simple rule of thumb for determining if a tripod is a necessity or not—the handheld or handholding rule. Basically, you take the focal length value and use it as the denominator of a fraction to get the minimum shutter speed (in other words, take the reciprocal of the focal length). That sounds more complicated than it really is. For example, let’s say you’re using a 90mm lens. That would mean that any shutter speed slower than 1/90 second would probably result in blurry pictures. Shutter speeds briefer than that will probably result in acceptably sharp pictures. This means that it’s easier to handhold a camera when using a wide focal length than it is when using a long one. A tiny bit of camera motion translates to far more movement with a telephoto than with a wide-angle lens. After all, if you’re using a 300mm lens that takes in 4° of the scene vertically, then the lens shifting a mere 1° represents motion covering a whole quarter of the image. But a 20mm wide-angle lens takes in 62° of the scene vertically. A 1° displacement represents a lower percentage of the whole image. To an extent, you can compensate for this by increasing the ISO (bigger ISO numbers mean a more sensitive image surface) but at the cost of a noisier image. You also need to multiply the necessary shutter time by your cropping factor when using a subframe camera.

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3.8 Stabilizers: a lens not shaken Wouldn’t it be great to have some sort of machine to compensate for camera motion? Well, we don’t have antigravity systems, but we do have gyroscopes and computer-controlled motors. If you’ve ever seen a nature documentary showing amazingly sharp aerial footage of elephants and giraffes grazing contentedly, undisturbed by the helicopter used to shoot the scene, then you’ve seen gyroscopes in action. They’re basically large housings containing heavy spinning motors that resist sudden changes in direction. With gyroscopic cameras, wildlife can be filmed from incredibly high up in the sky, so far away that the chopper noise doesn’t frighten the animals. Gyroscopes also permit long exposures at night from helicopters. Big gyroscopes are fine for wildlife documentaries or military reconnaissance, but what about the ordinary photographer who can’t afford a helicopter?

Optical image stabilizing ▲ A Kenyon KS-6 gyroscope. This heavy de-

This is where image stabilizing (IS) comes in. Image stabilizers contain electronic motion sensors. They also contain electric motors that can move a group of lenses within the lens barrel. They don’t use gyroscopes and don’t move the whole camera or lens. Normally light entering the lens strikes the film or sensor at a perfect 90 degree angle.

vice, powered by a separate battery pack, is used to stabilize the motion of professional still and video cameras.

Film or sensor

Motorized lens elements

But if the lens moves, the light comes in at a different angle or point, causing focus error.

A small group of stabilizing lens elements shifts automatically to compensate.

▲ When the lens senses camera motion, it instructs its motors to move the stabilization group, deflecting the light to compensate.

▲ It should be obvious which handheld photo was taken with stabilizing enabled and which one wasn’t.

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 Using a telephoto lens to make two signs seem much closer than they are for comedy value. The bustling crowds would have made a tripod an impossibility, and so image stabilizing came to the fore for this shot. Pike Place Market, Seattle, WA, USA. 200mm full frame. f/4, 1/90 sec. ISO 100.

Image stabilizing may sound like magic, but it actually works fairly well. However, there are some limits to the technology. f Most important, stabilizing can compensate for camera motion but

f f

f

f

f

never for subject motion. Stabilizers make a lot of handheld shots possible, but they don’t make photographing fast-moving kids or wildlife any easier. Stabilizing cannot substitute entirely for faster glass. A lens that lets in a lot of light has certain advantages over a slower stabilized lens. Stabilizers can only do so much. Lens makers often advertise their lenses’ abilities to compensate for however many stops of exposure (typically 2 to 5), but this must be taken with a proverbial grain of salt. Stabilizers adjust a small lens group by shifting it a small distance and can’t compensate for wild and crazy motion. Photography from the back of a bucking bronco or aboard a whitewater raft isn’t going to be any easier with a stabilizer. Stabilizers can actually cause blur when used with tripods. When a lens is stationary, a stabilizer can get confused because there’s no motion to compensate for (see photo on following page). Many stabilizers claim to have tripod-detecting capabilities, but in my experience it’s safest to switch stabilizing off when using a fixed mount. Panning, or moving the camera to track a moving object, can cause problems for stabilizers. Some lenses have special panning modes that stabilize in one direction only. The motors sometimes take a moment or two to get up to speed. So taking a photo immediately after engaging stabilizing mode can sometimes result in worse blur. It’s generally best to half-press the shutter release to focus, wait a brief moment, then take the photo.

▲ An image stabilizer, when bolted down to a tripod, can inadver-

▲ This professional lens has three stabilizer modes.

tently generate motion as shown here.

1 is normal, 2 is for panning, and 3 is exposure only.

There have been numerous improvements in stabilizing technology over the years, with manufacturers claiming more and more equivalent stops of stabilizing compensation. Sometimes these are billed as different “generations” of image stabilization technology. The range of motion that can be corrected for has also increased. Traditional IS, for example, can compensate for horizontal and vertical movement of the lens. However, “hybrid” IS can also compensate for rotational motion. This type of IS is well suited to macro photography. Optical image stabilizing is marketed under a variety of trademarked names. (Though at the risk of sounding pedantic, Nikon’s name is technically inaccurate because stabilizing doesn’t reduce vibrations: it compensates for motion.) Here are the main names you’ll come across: f Canon: Image Stabilization (IS) f Nikon: Vibration Reduction (VR) f Panasonic, Leica: MegaOIS f Sigma: Optical Stabilization (OS) f Tamron: Vibration Compensation (VC) ▲ The Nikon VR logo indicates the

In-camera stabilization The discussion so far has been about stabilizers built into lenses because, well, this is a book about lenses. However, there are also camera-based stabilizers that move the image sensor to compensate for camera motion. Such sensor-based stabilizers have the advantage of working with any lens you want. Pentax, Sony, and Olympus in particular are champions of in-body stabilizing. These three systems are named as follows:

presence of in-lens stabilizing.

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f Olympus: Image Stabilization f Pentax: Shake Reduction (SR) f Sony: Steady Shot Inside

While it works very well, sensor stabilizing can’t compensate for long focal lengths quite as effectively as lens-based stabilizing. It also can’t be added to film cameras.

3.9 The user interface

▲ A traditional manual-focus lens with two control rings for focus and aperture.

It may seem odd to say that lenses have user interfaces, but it’s a useful way of describing the controls you have for operating a lens. Most lenses are cylindrical in shape, and so the traditional controls consist of rotating rings. On an old-style manual lens, for instance, there are two rings. One ring is attached to a screwlike internal spiral, or helical, which moves various elements to adjust focus. The other ring adjusts the aperture. Zoom lenses may also have a third ring, used for adjusting the focal length. The rings may be knurled, ridged, or covered with rubber. The width, position, and construction of the adjustment rings vary considerably from lens to lens. Design is often a matter of style. For example, many lenses from the early 1990s tend to have relatively narrow focus rings made from plastic. Lenses from a decade later tend to have wider rings covered with easy-to-grip rubber. Generally, the later design is far more convenient to use.

Zoom control

▲ A simple mechanical lock to keep a zoom mechanism from moving during transport.

Most point-and-shoot cameras have powered zooms, which let you alter focal length by pressing a “wide” or “tele” button on the camera. However, most interchangeable lenses do not have motorized power zooms and require the photographer to physically adjust the lens. There are two basic types of zooms. Some lenses have a zoom ring as well as a focus ring and so are called “rotating zoom” or “two-touch.” Turning the zoom ring adjusts the focal length. Other lenses slide in and out like a trombone or telescope: the push-pull design. The push-pull design is more vulnerable to zoom creep than two-touch. Zoom creep isn’t some fast-moving paparazzo (plural: paparazzi) skulking off in the bushes, but the problem of the zoom accidentally adjusting focal length (sliding) when tilted up or down because the friction of the pushpull system isn’t enough to counteract the weight of the lens. Some lenses have locking or friction mechanisms to counteract zoom creep, whereas others have to be held down by something high-tech like gaffer tape or a rubber band. Some lenses also have zoom locks that lock the lens only in its shortest position for ease of portability.

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▲ Push-pulls tend to suck a lot of air, and therefore

▲ While most zoom lenses of the ’70s and ’80s had push-pull barrels,

dust, into the lens when adjusted. However, push-

this design is now considered uncool. Most zooms today have rotat-

pull lenses can be operated more rapidly, if usually

ing zoom controls, such as the Sigma lens shown here.

a bit less accurately, than two-touch zooms.

▲ Zooming a lens during a long exposure can create streaky hyperspace effects. It’s a great way for making a fairly drab scene, like this view of Reno, Nevada, USA (the world’s tallest little person) look more dynamic and exciting.

Direction of focus and zoom Focus and zoom direction depends on the manufacturer. When viewed from the photographer’s side of the camera, turning a lens ring clockwise does the following: Focus: Infinity to near (Canon, Olympus, Sony) Focus: Near to infinity (Nikon, Pentax) Zoom: Wide to long (Canon, Olympus) Zoom: Long to wide (Nikon, Pentax, Sony)

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Like water taps in different countries, the rotation direction is totally arbitrary, but it can be annoying or inconvenient if you use a lens you aren’t used to. Additionally, third-party lenses may or may not use the same rotation conventions you expect.

Clutch focus mechanism Some lenses from Tamron and Tokina employ a push-pull, or “clutch,” mechanism for switching between manual and autofocus (left). With such lenses, you just grab the manual-focus ring and slide it to disengage the autofocus motor.

Focus preset buttons Long professional telephoto lenses may have a group of small pushbuttons distributed around the end of the barrel. These can be used for presetting a desired focus distance. You just press the button to zip the lens straight back to that focus setting.

Switches Most lenses have various switches for enabling or disabling other features, such as autofocus or image stabilizing. They may also have switches for features like focus limiting, which restricts the autofocus seek range to a relatively close range (to avoid the problem of the lens slowly grinding out to infinity focus and back when doing closeup work).

Focus and zoom extension Some lenses physically change length when zoomed or focused, and some don’t. Many high-end lenses always stay the same length: they have “internal focus” or “rear focus,” and “internal zoom.” This avoids the problem of sucking in air mentioned earlier and can make it easier to weatherproof the lens. Such lenses can also be sturdier because all the moving parts are safely encased inside the barrel.  A lens with rear focusing moves the rearmost group of lens elements.

Other lenses telescope outward in one or two sections when focusing or zooming. This has the advantage of making the lens more compact when it’s stowed. But the exposed barrels can be more vulnerable to being knocked around.

Rotating ends Some lenses rotate at the end when focusing or zooming. This doesn’t really matter except when using certain types of filters, particularly polarizers and graduated neutral density filters. Such filters require specific alignment to work. It can be a huge pain to have to adjust your polarizer each time you refocus, so nonrotating ends are very useful.

Distance scale Better lenses include a little window indicating the approximate distance, in feet and meters, to which the lens is focused. In the case of macro lenses (see section 4.5), they also show the macro magnification ratio. To be honest, distance scales are rarely useful today. In the days of manual-focus lenses, when you had to rotate the lens a reasonable distance to get a noticeable change in focus (see page 244), distance scales were handy. But today’s autofocus lenses have such short rotational throws that the distance scales are very compact, rendering them somewhat useless. Some distance scales have markings in red, which are used for infrared photography (see section 8.34).

▲ The finely engraved distance scale of a Pentax macro lens.

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Depth of field scale A variant is the depth of field (DOF) scale. This is a distance scale with a few aperture numbers added. When the lens is set to an f-stop marked on the scale, then the area in acceptable focus is the distance indicated by the markings. DOF scales are mostly seen on prime lenses. They aren’t common on zooms because the DOF varies across the focal range. Some older push-pull manual-focus zoom lenses have curved color-coded lines as DOF scales, but these are not typically seen today.

3.10

To infinity—and beyond!

Older manual-focus lenses generally had a fixed endpoint for infinity focus. In other words, if you set focus to infinity, you wouldn’t be able to focus past it. It’s very convenient for astrophotography: you just point your lens at the night sky and turn the lens as far as it’ll go. However, autofocus lenses generally let you turn the focus ring past the infinity mark. Such lenses are intentionally designed this way to allow them to compensate for changes in ambient temperature. The focus point of a lens can be affected by thermal expansion.

3.11

Lens electronics

Modern SLR camera lenses are very complex. In addition to the glass elements, there are electronics that handle features such as aperture control, autofocus, and image stabilizing. These features are operated digitally on modern cameras, and so lenses contain electrical interfaces to the camera and onboard computer circuitry. The interfaces are visible as metal pins and contacts on the camera and lens mount. The following data is commonly transmitted: f Basic properties of the lens, such as minimum and maximum aperture

settings and focal range f Current focal length f Unique exposure characteristics, which may require some compensation

on the part of the camera f In the case of lenses with electronically controllable diaphragms, instructions to set the lens aperture—when, and what stop f In the case of lens-based autofocus, instructions to the autofocus motor f With some systems, distance data (i.e., the distance from subject to camera, at which focus is set)

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In short, the lens electronics tell the computer in the camera, “This is what I am and what I can do,” and in return the camera tells the lens what settings to use and when. Digital cameras also record lens information as part of each photo’s exchangeable image file format (EXIF), as shown below.

Electronics first started showing up inside lenses in the late 1980s and early 1990s. The circuitry in a lens is often referred to as its chip or central processing unit (CPU), though modern lenses usually have multiple chips on small circuit boards.

3.12

▲ This printed circuit board (PCB) fits around internal lens components.

What’s in a name?

There are two basic traditions when it comes to product names for lenses. European makers such as Zeiss and Leica go for names. In the past, the names referred to actual people, such as the Cooke triplet or the Petzval portrait. Other times, makers just created cool-sounding names that resemble science fiction planets, such as Planar, Biogon, Elmar, Hologon, Noctilux, and Distagon. And sometimes the names are a bit silly. For example, the Leica Hektor and Summarex were allegedly named after lens designer Max Berek’s dogs. The name refers to a general optical design for one type of lens, regardless of its size or nonoptical characteristics. For example, lots of cameras and lenses use the Zeiss Tessar four element design (tessare being Greek for four).

▲ In this week’s episode the captain has to negotiate a peace treaty between the Sonnars and the Distagons of Heliar IV.

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3.13

▲ A friend was going to ask for the Tamron SP AF 70–200mm F2.8 Di LD (IF) Macro as a birthday present but couldn’t remember its name.

 While the Canon EF 50mm 1.8 lens and its Mark II successor have nearly identical glass, the original lens is much more sturdily built and has a distance scale and metal mount. But only the “II” separates the names. Incidentally, note the gold sticker on the older lens. From the 1960s to late ’80s all Japanese camera products were inspected and labeled for quality control by the Japan Camera Inspection Institute. This was an important part of Japan’s industrial transformation from a country known for low-quality merchandise to one respected the world over for top-quality products.

Alphabet soup

By contrast, Asian makers typically use more sober and practical lens names based on lens data. They may have a marketing name for their line of lenses—Nikon lenses are known as Nikkors, for example. But each individual lens is described by its technical attributes, such as Canon EF 17–40 4L USM. Dull, admittedly, but sensible and usually informative. A notable exception is Cosina, which sells Japanese-built lenses under the classic German Voigtländer name. As part of the branding, it uses names like Skopar, Ultron, and Nokton. However, figuring out a lens manufacturer’s cryptic naming scheme can be as challenging as decoding a pay-by-the-word personals ad. Especially when lenses have crazy long names like SMC Pentax-DA 18–135 3.5–5.6 ED AL IF DC WR or Sigma APO Macro 180mm f/3.5 EX DG IF HSM, which describe all manner of features, many of which aren’t fully documented on maker websites. The guide on the next page should make it easier to decipher the names. It’s very important to get the name right because two lenses may have almost identical names yet one might be a high-quality professional product and the other a low-end consumer product. Or a version II lens might be completely different from its predecessor. And you don’t want to buy the wrong lens by mistake, such as mixing up a 50mm 1.2 lens with a 50mm 1:2 lens. (The former means f/1.2; the latter means f/2.0.)

3.14

Decoding a lens name

Most lens makers use the following basic structure in their naming schemes, with some variations: f Manufacturer or product line name. f Lens mount may be listed. f Focal length. For prime lenses, a single number in millimeters is listed.

For zoom lenses, the range is listed: both the shortest and longest focal lengths. f Maximum aperture, often prefixed by the “1:” which, frankly, I find confusing and unnecessary. Prime lenses and zooms with a constant aperture across the range have a single number. Variable aperture zooms list the maximum aperture at the shortest and longest focal lengths. f Finally, any manufacturer-specific features or acronyms. There are countless maker-specific terms that can appear in a lens name. The most common acronyms and terms are listed in Appendix B at the end of this book, grouped by lens manufacturer. Given this information the following example lens names can be decoded: f Canon EF 70–200mm 1:2.8L IS II USM. Canon autofocus (EF mount)

lens. Zoom, with a range from 70 to 200mm. Maximum aperture is f/2.8 throughout the focal range. Professional product, part of Canon’s L series. Image stabilized and with an ultrasonic focus motor. Second version (mark II) of this lens type. f SMC Pentax-DA 18–135 3.5–5.6 ED AL IF DC WR. Pentax autofocus lens for subframe (DA) digital SLRs. Zoom, with a range from 18 to 135mm. Maximum aperture is f/3.5 at the wide end and f/5.6 at the long. Contains extra-low dispersion glass (see section 8.8) and an aspheric lens element (see section 8.10); has internal focusing, a DC autofocus motor, and weatherproofing; and is equipped with Pentax Super Multicoating. f Nikon AF-S Nikkor 50mm 1:1.4 G. Nikon autofocus lens with ultrasonic (Silent Wave) motor. 50mm prime. Maximum aperture f/1.4. G lens, and so lacks an aperture adjustment ring—aperture setting must be set by the camera body. f Sigma APO Macro 180mm f/3.5 EX DG IF HSM. Sigma prime macro lens with a focal length of 180mm. Maximum aperture is f/3.5. Lens is of Sigma’s high-end EX type, designed for full-frame digital cameras, and has internal focusing and an ultrasonic (HyperSonic) focusing motor. Lens also contains apochromatic glass, meaning it’s designed to reduce chromatic aberration.

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3.15

Serial numbers

These numbers, printed or engraved on lens barrels, vary in structure from maker to maker. Sometimes the year of manufacture and the factory are encoded in the number, which is of interest to collectors. On the whole, serial numbers are just useful for warranty and insurance record purposes.

3.16

Build quality

Optics is the key factor when buying a lens. But it certainly isn’t the only thing. After all, a cheap lens that breaks the first time it gets bumped against a wall isn’t much use, no matter how great its glass is. Accordingly, the product’s standards of construction, or build quality, are pretty important too. Lens manufacturers are highly optimized companies and do little by accident. Every lens is built to carefully calibrated price points. Inexpensive lenses made for the casual consumer market are built very differently from the handcrafted lenses sold to full-time professionals. This isn’t to say that cheaper lenses are crummy—just that a lens optimized for affordability simply has different design goals than one aimed at the pro market. So in a real sense, you get what you pay for with most lenses. Good lenses are precision optical instruments and costly to build.

3.17

▲ They don’t make ’em like this anymore! An Asahi (Pentax) Super Takumar 50mm 1.4 lens, built around 1968.

Lens barrel construction

Far back in the mists of ancient time, in the great and glorious days of manual focus, lens barrels were crafted from solid metal. They boasted precisely machined rings that turned with a silky smoothness. Focus rings were “well damped,” meaning they were lubricated with special grease for a smooth and velvety feeling. Nothing loose, wobbly, or rattly here. The precision of these beautifully constructed lenses was lovely indeed. But the arrival of autofocus technology presented two problems. First, the vagaries of electric gearing systems require a little leeway in motion. Second, the labor costs of producing handcrafted marvels is incompatible with mass-market pricing in a modern age. So today, the vast majority of camera lenses have plastic barrels. This has some pros and cons:

Solid metal construction and excellent glass. However, this particular model

f Plastic is lighter than metal. Metal feels great in the hand, but not so

harbors a dark secret—see section 8.4

great on the shoulders on a long hike. f Plastic is more affordable, though it can also feel cheap.

on radioactive lenses.

f Quality plastic can absorb light impacts without cracking. To reassure

customers, lens makers often talk of using “engineering plastics.” f Metal is sturdy, but it can deform. It’s pretty common to see secondhand metal-barreled lenses with light dents that prevent rings from turning or that jam the filter mount. f Metal has better abrasion resistance. A metal lens mount wears more slowly than a plastic one (though an amateur who never changes lenses won’t notice it). f Metal is generally better suited for precisely moving internal parts, such as zoom cylinders and helicals. Aluminum filter rings can sometimes seize up and bind on metalf barreled lenses. Heavier brass filter rings generally don’t do this. f Painted metal surfaces reveal bright metal when scratched. This is known as “brassing,” though the metal underneath isn’t always brass. f Barrel construction has nothing to do with the optical properties of the lens. Most interchangeable plastic-barreled lenses contain glass lens elements.

▲ This lens has a plastic mount to keep costs and weight to a rockbottom low.

Modern metal lenses Not all products are plastic fantastic. There are some exceptions: f Canon L and Nikon ED. Many, though not all, Canon and Nikon pro series

lenses feature metal or partly metal barrels. Generally, the larger telephotos have more metal components. Shorter lenses tend to use heavyduty plastic. f Zeiss. Many Zeiss-branded SLR lenses are built in Japan by Cosina and are old-style manual-focus lenses with metal barrels. ▲ This sturdy professional lens has suffered a lot of abuse over its career. The paint is chipped, revealing the metal underneath. The rubber weather seal is also completely torn off.

 Zeiss-branded manual-focus lens with Nikon lens mount.

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f Leica. True to its premium pricing, Leica continues to use machined

metal barrels. With the exception of the Leica S2 system, these are all manual-focus lenses. f Pentax Limited edition. Famous for beautifully crafted manual lenses in the 1960s and ’70s, Pentax reflects this legacy with a small line of metalbarreled lenses.

3.18

Lens marketing categories

Smaller lens makers, or specialized European manufacturers, don’t subdivide their product lineup. But the bigger lens makers generally design their lenses to fit two or three categories, such as professional, advanced amateur/prosumer, and consumer. The categories encompass different levels of build quality and optical quality.  There’s no reason why you can’t put a pro lens on a consumer camera, or a consumer lens on a pro camera, as long as they use the same lens mounts. The result might be a little unbalanced to hold, though.

▼ A sturdily built lens aimed at professional users.

A wide product range is great for beginners because it means you can start out with an affordable camera and lens, then gradually build up your collection to include higher-quality gear while maintaining full compatibility across the line. Sometimes a lens maker will deliberately advertise what category a given product is in, and other times you need to do some research to find out where a given lens might fit in the lineup. But please remember that these descriptions aren’t moral judgments! Sometimes people get very upset when someone says that their pride and joy acquisition isn’t a professional lens.

Professional Full-time photographers typically have very specific demands. They need the best optical quality they can get, they need tough and reliable weatherproofed lenses that can be used day in, day out without failure, and they often need specific technical or user interface features. Professional lenses

are built for this market and priced accordingly. Canon and Nikon both make a wide selection of pro lenses, but smaller makers typically don’t.

Advanced amateur Photography is marked by a lot of talented, experienced, or simply enthusiastic photographers who don’t necessarily need the rugged build quality of a professional lens. Or who simply can’t afford to spend that much money. These midrange products typically offer good compromises between cost and performance.

Consumer Products aimed at the consumer market are highly sensitive to price. They’re built around affordability, and other design choices generally take a lower priority. In particular, consumer lenses are of lower optical quality and are rarely built to be particularly rugged.

3.19

Notable marketing categories

Canon Canon EF lenses are traditionally divided into four basic categories. Of the four, only L is a formally identified product category.

▲ An affordable consumer lens.

Canon L. High-end professional lenses make up the company’s L series, for luxury. Marked by a red ring at the end, these lenses must have a number of features: f At least one lens element must be ground aspheric,

fluorite, or ultra-low dispersion. f Sturdy build. Longer lenses tend to have solid magnesium lens barrels, for example. f Newer L lenses are weatherproofed. f Nearly all L lenses have ultrasonic motors. Canon advanced amateur. Canon doesn’t identify its midrange products specifically, though many have ultrasonic motors and thus carry a striped gold band. Canon’s non-L primes fall into this category as well—good optically, but don’t have or need the exotic lens elements that are the hallmarks of L lenses. Nor do they boast pro build quality.

▲ An L-branded Canon lens.

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Canon consumer. Canon sells a lot of lenses to the price-conscious consumer market. With a couple of exceptions, most such lenses are marked with a chromed silver ring. A plastic lens mount and the absence of a distance scale are two additional clues that a product is aimed at the mass market.

▲ An inexpensive Canon consumer lens.

Canon special case. Canon also sell a number of expensive and unusual lenses, such as its super-macro MP-E lens and tilt-shift TS-E lenses. These aren’t technically L lenses, but they have expensive optics.

Nikon Nikon doesn’t specifically label its pro lenses as such, though the company’s ED lenses do fit the description. ED lenses contain extremely low dispersion glass, and Nikon has traditionally included this glass in only its best lenses. Accordingly, lenses with the gold ED badge usually also feature sturdy build quality.

▲ This pro lens bears the ED branding.

Sigma Sigma has essentially two build quality levels: EX (pro) and ED (consumer). Recent EX lenses are all constant aperture models and have a sturdier build quality.

▲ Sigma EX badge.

▲ A low-cost Sigma ED lens.

Sony Sony G. Sony produces a handful of high-end lenses for the professional market under the G label, for gold.

Sony Carl Zeiss. Sony has teamed up with German lens maker Carl Zeiss to produce a handful of pro-quality Alpha-mount lenses. Sony Consumer. The rest of the Sony lens lineup is aimed at the consumer market.

3.20

Colored rings

Many lenses have colored rings around the ends of the barrels. Sometimes they indicate certain features, and sometimes they’re just there for marketing. Here are some makers’ color choices. f Canon g Red. An L series professional lens. g Gold dashed. Non-L lens with an ultrasonic motor. g Green. Contains diffractive optic (DO) technology. g Chrome/silver. Affordable consumer lens. f Nikon g Gold. Either the lens contains ED glass and is therefore of a high pro-

fessional specification or Nikon wanted it to look good (usage is not consistent). f Pentax g Green. Designed for digital cameras. f Sigma g Gold. Part of the EX line of higher-end lenses. g Red. Originally indicated apochromatic glass for reduced color fringing;

now used for marketing purposes only.

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f Samsung g Blue. All Samsung NX lenses have blue rings as part of the branding. f Tamron g Blue. Can indicate lens has a clutch focus mechanism in manual-focus

mode.

3.21

Kit lenses

The first lens that most people own is the lens that comes with the camera. Most consumer-level SLRs sold today come bundled with a low-cost lens, known as a kit lens. This is an inexpensive standard zoom that covers a general-purpose range of about 28 to 90mm in the case of full-frame cameras, and perhaps 18 to 55mm in the case of cropped digital sensors. And people often want to know, is this lens good or bad? The answer really depends on what you’re looking for. Here are some key points to consider: ▲ A pair of low-cost kit lenses.

Pros: f Kit lenses are affordable. There’s no need to go and buy something else because the camera and lens are in the box and ready to go. f They are general-purpose lenses. The zoom range is ideal for a wide range of photographic subjects. f The image quality is acceptable. They certainly take better shots than your typical point-and-shoot. f They are lightweight. Optically superior lenses are usually heavier and more cumbersome. Cons: f Kit lenses are engineered for affordability. Each lens design is a compromise, and in the case of kit lenses, the primary engineering goal is to keep the price down. Other priorities are secondary. f They are slow. Typically they range from f/4 at the widest to f/5.6 at the longest. Even shooting wide open, you don’t get a lot of light hitting the film or sensor. f They are no good for anything other than the most general needs. They’re hopeless for macro work, aren’t particularly wide, don’t let in a lot of light, and don’t have much reach (telephoto range). f They are fine for consumer point-and-shoot snaps, but they aren’t particularly sharp. Their optical performance is only okay when you consider the cost. This isn’t to say they’re terrible; they generally take perfectly decent pictures if stopped down to f/8, say. But you can’t expect incredible optical performance.

f They are the hallmark of a beginner. Walking around with a kit lens

is a sure way to look like a novice, if that sort of thing makes you uncomfortable. In short, kit lenses are fine if you’re new to interchangeable lenses. They’re a good way to start using the camera while you decide how you’ll build your lens collection. But they also place a lot of limitations on the abilities of the camera. There’s nothing wrong with sticking with the kit lens, but you certainly aren’t taking full advantage of your camera by doing so. Note that midrange and high-end SLRs rarely come equipped with a lens. This is like buying a violin without a bow. The reasoning is that people in the market for an advanced camera generally either already have a lens collection or have specific needs in mind.

3.22

White lenses

Any major news or sports event today will reveal a photographer’s pit bristling with an array of large white-painted lenses. Why are these lenses white when most barrels are black? Most white lenses are produced by Canon, which builds synthetic fluorite crystal (see section 8.8) into its longer telephoto lenses. Fluorite is quite sensitive to heat, expanding under high temperatures. For this reason, Canon started painting the barrels of fluorite-containing lenses a light almond/off-white color to reduce heat absorption when the lenses are out in the sun. And of course the visual potential of an unusual barrel color isn’t lost on Canon’s marketing department. Some other lens makers also paint their barrels light colors, though more for marketing than technical reasons. It’s not uncommon for consumeroriented lenses to be colored silver.

▼ A Canon “great white” lens.

 Pentax Q lenses and camera.

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3.23

▼ The sun rises through the mist. Serpentine River, Surrey, British Columbia, Canada. 200mm full frame. f/8, 1/640 sec. ISO 100.

Safety

It’s worth mentioning that there are safety issues related to camera lenses. Both involve the sun. As you learned on your first camping trip, the rays of the sun can be concentrated by a simple lens such as a kid’s magnifying glass. Given enough time, the resultant heat at the focal point can be so intense that it can cause wood or paper to burst into flame. Camera lenses also concentrate light. In the case of mirrorless cameras and rangefinders, it’s definitely a bad idea to leave the lens uncapped and

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pointing at the sun for extended periods, as the heat buildup can damage the camera’s internals. SLRs can also have this problem when in Live View or mirror lockup modes. It’s also important never to look at the sun through an optical SLR viewfinder or camera lens. Doing so can concentrate the power of the sun’s light on your eye’s retina, frying it permanently. At sunrise and sunset it can be tempting to frame shots through an SLR viewfinder, but it’s always safer to use your Live View LCD monitor in these cases.

3.24

Cold weather

When shooting in cold weather, it’s worth taking some precautions to protect camera gear. Just as eyeglasses fog up when you go inside on a winter day, condensation can form on internal lens components, ruining them. To avoid the problem, put your camera into a plastic bag before bringing it indoors. This allows the condensation to form on the bag rather than on your precious gear.

▼ Piccadilly Circus, London, England. 70mm full frame. f/4.5, 1/80 sec, ISO 400.

CHAPTER 4

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4

Choosing the right lens for a project

4.1 Choosing a lens One of the first questions asked by beginners is, what lens should I buy? The answer naturally depends on your needs. Here are some things to consider: f What is your budget? f Do you have a specific need? Did you buy your camera with a certain

▼ 65mm full frame. f/4, 1/100 sec. ISO 50, studio flash.

purpose in mind? There’s no point in buying a long telephoto if you’re mainly interested in photographing stamps, for example. f What focal length range do you use the most? One of the great things about digital cameras is that they record shooting data for each picture. You can then use an image cataloging program to sort photos by focal length, aperture, and so on. If you find yourself using a certain range a lot, maybe it’s worth investing in a high-quality lens that covers that range. f Conversely, what do you find yourself missing? When you take shots, do you always end up at the wide end of the lens, wishing you could go wider? Or do you find yourself at the long end, longing to be able to reach further? Think about what’s wanting in your best shots.

f What are your plans? Do you intend to build up a

stable of different lenses so you’re ready to take on any photographic assignment? Or are you mainly interested in just getting one or two lenses that cover fairly general photographic cases? f Do you want to set yourself some challenges? If you’ve got a zoom, try choosing a focal length, taping it down, and shooting only pictures using that setting. Imagine you’ve got a fixed lens in your camera and every shot has to be 28mm or 100mm. How does this affect your work?

4.2 Portraits One of the first things that people did with cameras, as soon as it became technically feasible, was take pictures of other people. Portraiture in one form or another is the most popular photographic activity there is. Accordingly, there’s a fair bit of mystique around portraits and the right lens to use. So first of all, is there such a thing as a portrait lens? Well, not literally. Any lens can and has been used for portrait purposes. However, for reasons of tradition, aesthetics, and practicality, certain lenses are more commonly used than others. In fact, a fairly standard group of lens criteria has been used ever since Josef Petzval invented the first real portrait lens in 1840.

▲ 45mm full frame. f/11, 1/125 sec. ISO 100, studio flash.

 A typical mid-nineteenth century portrait lens of Petzval design, from the Zeiss Optical Museum collection, Oberkochen, Germany. Manufactured by Voigtländer in Germany to avoid Petzval’s Austrian patent. Though he died an impoverished and embittered man, having watched Voigtländer and others make fortunes from his lens, Josef Petzval is remembered today for his breakthrough work in applying mathematics to optics.

And note that this discussion is about traditional portraiture—face only, or head and upper shoulders/chest. Full-body photographs aren’t portraits for the sake of this discussion.

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Focal length

The first consideration is focal length. Generally speaking, portraits are supposed to make the sitter look reasonably good. So unless you’re going for comedy value or you’re taking a full-body shot in the context of a given scene, it’s generally best to go for shorter telephotos than wider-angle lenses. The reasons for this are discussed in section 5.9. Really long telephotos are typically unhelpful because they require huge distances from camera to subject. This can be fine outdoors, though it’s hard to offer private directions to a model when shouting down a megaphone or directing via an assistant on a radio. But it’s problematic in smaller studios where there’s simply no room to move further back. ▲ 55mm, 1.3x crop. f/11, 1/125 sec, ISO 200.

Traditional focal lengths The convention is to use a short telephoto, which has a focal length of at least 85mm on a full-frame camera. This focal length gives you a flattering perspective when shooting someone’s head and shoulders (see section 5.8 for more on perspective.). Generally, 85mm, 100mm, and 135mm are popular portrait lenses. When using a subframe sensor camera, you can go for slightly shorter lenses, such as 50mm through 85mm.

Apertures

▲ 100mm full frame. f/8, 1/60 sec, ISO 100.

Next, wide apertures are a good thing. A common portrait technique is to use a very narrow depth of field and focus on the eyes. This has a couple of advantages. First, it quite effectively draws the viewer’s attention to the proverbial windows to the soul. And second, it tends to throw the background neatly out of focus. This is a great way of transforming a busy and cluttered background into a nice abstract wash of color. In modestly financed studios, this also helps conceal imperfections in the backdrop. Prime lenses with fast apertures like f/1.8 are good for this sort of thing, especially on full-frame cameras. Unfortunately, since depth of field is also dependent on the size of the image sensor, it’s harder to achieve narrow depth of field with a lot of mirrorless digitals. Next, portraiture is generally done in a fairly controlled environment, like a studio. This is unlike the snap-and-grab world of photojournalism or sports photography, where time lost reframing an image could be the

 The left-hand portrait uses a small aperture setting of f/18, and as a result background trees are visible. By opening up to f/2.8 the background recedes into a gentle blur. 200mm full frame. f/18, 1/10 sec and f/2.8, 1/500 sec. ISO 100.

difference between getting a shot and missing it. Accordingly, prime lenses with fixed focal lengths are typically favored for their high image quality— there’s less reason to go for zooms. Manual-focus lenses (see section 9.1) actually make pretty good portrait lenses. There’s usually time for manual focusing, and the optical quality of many older prime lenses still holds up well today. In fact, ancient lenses with blurring around the edges or darkened corners can be fantastic tools for moody or evocative portraits.

4.3 Landscapes The lenses used to shoot landscapes and outdoor scenes are as varied as the subjects themselves. But there are still some common points to consider. First, landscapes generally don’t move very much. Obviously there are exceptions, such as scenes involving animals, cars, trees blowing in the wind, or hurricanes. But on the whole, the priority is to capture a scene, not to freeze motion. For this reason landscape work frequently involves tripods and a contemplative, measured pace. This isn’t photography that cries out for image stabilizing, rapid autofocus, and huge apertures. Accordingly, tripods and manual focus are often the primary tools. Second, when most people think of landscapes they tend to think of sweeping immersive scenes—photographs that transport you to another place or make you feel like you’ve stepped into the frame. This generally implies wide-angle lenses and extreme depth of field so everything is in focus.

▲ An 85mm f/1.2 lens designed mainly for portraiture.

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 The torii arch at Oyunohara. Near Kumano Hongu-taisha shrine, Wakayama Prefecture, Japan. This steel arch may be one of the largest in the country at 33.9 meters, about 110 feet, tall. It was built in 2000. 17mm full frame. f/4, 10 sec, ISO 100.

▲ This view of Manhattan is a high dynamic range (HDR) shot comprising three separate exposures of the same scene, blended in a computer. New York, NY, USA. 17mm full frame. f/5, ISO 100.

▲ The dramatic landscape of Cappadocia, Turkey, as seen from a hot air balloon. 80mm full frame. f/5.6, 1/180 sec. ISO 100.

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Third, landscape photos are generally expected to be sharp. Painfully, crisply sharp. This, and the general lack of a need for rapid shooting speed, means that fixed focal length primes are common. Zooms don’t always confer the same advantages, and primes are typically sharper. So, traditional landscape photography usually involves wider prime lenses, with an emphasis on sharpness over flexibility (zooms) or large apertures. But that shouldn’t mean that this is the only way to go. For example, telephoto lenses are extremely valuable for picking out details in a distant scene. A wide-angle lens might record just banal clutter compared to the way a telephoto can flatten perspective, transforming distant hills into curved abstract shapes. A telephoto can record a sunset or moonrise in dramatic fashion, allowing the celestial body to be depicted in the image as a large disc rather than a tiny dot.  A 200mm telephoto picks out a Joshua tree, somewhere in the Mojave Desert, California, USA. Color desaturated in post. 200mm full frame. f/4.5, 1/250 sec. ISO 100.

 The otherworldly hills of Zabriskie Point at dusk. Death Valley National Park, California, USA. 200mm full frame. f/8, 3.2 sec, ISO 200.

Of course, there are other choices. A backcountry hiker might go for a high-quality zoom for maximum flexibility, for example. It’s all very well to drive to a site in a cushy 4×4 (or, in the case of Ansel Adams, ride on a far more environmentally responsible pony), but a self-reliant hiker doesn’t have that luxury and may not want to carry a huge and heavy selection of various prime lenses. Legendary nature photographer Galen Rowell would go on epic hikes with a single 35mm camera and just a lens or two. Next, the rise of digital has transformed a lot of landscape photography techniques. It’s now possible to stitch together multiple shots from the same scene, resulting in a vast and seamless panorama. Such panos can be assembled without extreme wide-angle lenses. Finally, who says landscapes have to be pin sharp? Dreamlike, textured, and ethereal photos were the goal of the pictorialist movement of the late 1800s and early 1900s. There’s no need to be literal in photography.

4.4 Kids Since time immemorial (well, at least since affordable cameras came on the scene), children have been a major force driving people to buy cameras. In fact, the acquisition of a decent camera seems to be one of the first impulses of any proud parent. But children are a particularly challenging photographic subject, since they move around so quickly and unpredictably. Even Victorian photos, taken during a stricter age when children were sternly ordered to stand immobile for the duration of the shot, frequently contain lots of motion blur where kids are involved. One way of solving the problem is to use flash because the brief duration of a flash pulse is great for arresting motion. This works, but direct flash can be a harsh and unflattering form of light. It’s best to use off-camera or indirect (bounced) flash, to avoid flat, unattractive shots. Another way is to use fast glass. Lenses with large apertures are great for fast-moving kids; the main drawback is the shallow depth of field. Focus motor speed is also important, and ultrasonic SLR lenses work well. Mirrorless cameras are mostly much slower than DSLRs and, although they’re more compact and discreet, can result in frustration due to missed shots. Here are a few other ideas: f Get down to their level. Children are people, and looming over them isn’t a great way to convey their individuality. f Capture them doing something, or team up with someone to draw their attention away from the lens. Most kids are great at hamming it up for the camera, but you probably won’t want an entire collection of shots where the kids are frozen in strange rictus grins.

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f Take a lot of photos. A lot. In today’s digital world the incremental cost

▼ To get this shot I had to lay on the ground,

of shooting tons of photos is basically zero. So don’t be shy about taking loads of shots and disposing of most of them in the computer. It’s a fine way to catch those spontaneous moments.

sticking my camera right into a patch of tulips while a procession of Dutch tourists walked by, staring at me like I was crazy. The

4.5 Closeup or macro photography

things one does for art. I was quite lucky to get the tiny spider in perfect focus, because I was using an extension tube and therefore had to focus by moving the camera, which didn’t have Live View. Keukenhof gardens, Lisse, Netherlands. 25mm, 1.6x subframe, 20mm extension tube. f/6.7, 1/90 sec. ISO 100.

Smaller than a postcard; bigger than an ant. Welcome to the tiny world of macro photography. Closeup photography has traditionally been known by a rather confusing and counterintuitive name—macro photography. The idea is that closeup work involves taking photos of small objects, then enlarging them to prints larger than (macro) the original subject. Nikon is one exception— its macro lenses are marketed as “micro” lenses.

Regardless of the strange name, macro work essentially means photographing things that are tiny, but not microscopic and thus invisible to the naked eye. Special tools and techniques are required to do macro right, and it can inspire a lifetime’s work. The most ordinary things can suddenly be transformed when viewed at a macrophotography scale.  A ladybug makes its way across a massive field of huge metal boulders. Each sphere is actually a tiny metallic cake-decorating sugar ball (or dragée). Note how shallow the depth of field is: only a couple of rows of dragées are actually in focus. 100mm macro with 20mm extension tube, full frame.

True macro lenses A lot of lenses have settings marked “macro.” Or they may have a setting marked with a flower icon, meaning closeup work. Sadly, the majority of these lenses are not true macros at all, despite the misleading labeling. The traditional definition of macro is a lens with a 1:1 magnification ratio. In other words, an object as small as the image area can be photographed. In the case of 35mm film or full-frame 35mm-equivalent digital, that means an object as small as 36 by 24 mm. Ordinary non-macro lenses might have a magnification of only 1:4, say, at the closest setting. This would mean the smallest object that could be photographed would be 144 by 96 mm in size. Not really that close up. True macro lenses have a number of features other than 1:1 that make them ideally suited to closeup photography including the following:

▲ This is a semi-closeup shot taken with a non-macro kit lens. It’s possible to see the little crabs under the rock, but this is as close as you can get. 105mm, 1.6x subframe. f/4.5, 1/60 sec. ISO 800.

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f Unflinchingly high resolution. Macro lenses are often made with the f

f f

f f

▲ A macro lens equipped with a dedicated-ring flash unit.

sharpest glass that a manufacturer can produce. Flat field reproduction (see curvature of field, section 8.13). In other words, a flat object like a postage stamp will be correctly in focus from the center of the frame to the edge. Many non-macro lenses lack this capability. Long focus throws, making precise manual focus much easier (see page 244). Focus limiters, or simple switches that allow an autofocus mechanism to focus across either the entire range or only the macro range. This is very important for macro work because you don’t want the camera wasting time trying to focus outside the macro range. Distance scales (see section 3.9) that indicate the magnification ratio. Ring flash mounts. Macro lenses often have to be positioned extremely close to their tiny subjects, which makes lighting very difficult. A ring flash, which is simply a flash unit with curved tubes that fits around the end of the lens barrel, is perfect for many types of closeup illumination. The light can be flat and a bit boring, but at least it’s even. Many macro lenses are compatible with ring flashes made by the same manufacturer. There’s no cross-manufacturer ring flash attachment standard, though.

Most macro lenses are perfectly serviceable as regular lenses as well. In fact, they often make excellent portrait-length lenses—the only problem being they can sometimes be too flaw-revealingly sharp! The Canon MP-E supermacro is one exception because it’s macro only.

Supermacro Most macro lenses can only go as far as 1:1 magnification, but the Canon MP-E 65mm 2.8 is an unusual lens that can achieve 5 times that and so can photograph objects as small as 7 by 5 mm in size. It’s quite expensive and difficult to use, and it’s also incapable of infinity focus, making it a macroonly lens. However, it’s also capable of some remarkable results.

Macro focal lengths

▲ A Tokina 100mm macro lens.

There are three basic focal lengths for macro lenses on a full-frame camera: 50mm, 100mm, and 180mm. Lenses that are 50mm are short macro lenses. They’re fine for static objects like postage stamps but aren’t very good for animate macro subjects, particularly skittish insects, since the lens has to be extremely close to the subject. This distance between the end of the lens and the subject is the working distance. Short working distances also make illumination difficult because light is often blocked by the lens itself.

 The Canon 65mm MP-E supermacro lens has the most astounding helical extension of any lens I’ve seen.

Lenses that are 90, 100, and 105mm are normal macro lenses. This length is a good trade-off between cost and working distance. Most companies make macro lenses in this range. Lenses that are 180mm are telephoto macro. Ideal for photographing nervous dragonflies and other insects from afar, they offer a lot of working distance but are quite expensive. The long focal lengths also magnify camera motion, making them more difficult to use. There are also macro lenses designed for subframe SLRs. The Canon EF-S 60mm 2.8 and the Nikon AF-S DX Micro Nikkor 40mm 2.8 are two examples.  Fossilized trilobite molt. Trilobites were small arthropod sea creatures that roamed the Earth’s oceans millions of years ago. Like modern shelled creatures they would shed their old shell and grow newer, larger ones in a process known as molting. Standard macro lenses are ideal for photography of artifacts like this in the field. 100mm macro, full frame. f/16, 1/125 sec, ISO 320.

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Stabilizing Image stabilizing can be very helpful at macro distances, especially when shooting insects handheld in the field. A number of lenses are available with special stabilizing systems optimized for short magnifications.  A drop of water on a bird of paradise flower shows how vanishingly narrow the depth of field can be when shooting at macro distances with a lens wide open. This picture was taken handheld, and it took a few tries to nail focus on the droplet. 100mm macro, full frame. f/2.8, 1/400 sec. ISO 200.

Macro without a macro lens There are many other ways to take closeup shots without an expensive dedicated macro lens. Some of these tools and techniques are detailed in section 65.

4.6 Sports Good sports photography is definitely one of the bigger photographic challenges out there. You’ve got fast-moving subjects, often challenging light conditions, distance restrictions to your subjects, and of course the complete inability to go back and reshoot an event. It’s no surprise that sporting event photography is not an easy field to master. Here are some points: f Speed. Athletes are going to move quickly and unpredictably. Rapid auto-

focus and a lot of experience about the likely movement of each person are both essential. f Light levels. A football field on a sunny day is no problem, but a lot of sports locations have less light than you’d expect. Even seemingly intense artificial lighting can be insufficient, and flash is often banned. Fast glass is therefore essential.

f Distance. Most sports venues are very large, and frontline positions are

scarce and highly coveted. An athlete on a football field, on a hockey rink, or in an Olympic pool can be a very long way away. There’s a reason sports photographers always haul giant telephoto lenses around. There are a few exceptions—basketball courts are fairly compact, for instance. But distance issues are one key reason amateurs can never get great magazine-cover shots of pro games. Restrictions on the type of lenses permitted by unaccredited photographers is of course another reason.  A very fast Nikon 200mm f/2 lens. Its gaping maw reminds me of a filter-feeding basking shark, though these lenses suck up light and not zooplankton.

In short, pro sports shooters use very long and fast lenses (i.e., huge and expensive) for good reason. This is all very discouraging if you want to photograph your friends on the field or your kids on the rink. Huge 400mm f/2.8 lenses aren’t exactly cheap. But here are a few ideas: f Buy or rent the fastest long lens you can afford. f Try to get as close to the action as you can. In the case of a professional

sports event, this probably won’t be possible, but it might be easy for an amateur game. f Use a high ISO. This lets you keep your shutter speed high, though at the cost of noise in the image. f Use fast glass. The bigger the maximum aperture, the better. Not only will it be possible to use higher shutter speeds to reduce blurring, but autofocus systems are faster when given more light. f Use a tripod with a head attachment that lets you pan to follow the action. This will reduce camera shake from affecting the final shot.

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f Track and predict the action. Walter Gretzky, father of hockey giant

Wayne, is quoted as saying, “Go to where the puck is going, not where it has been.” While it’s the sort of quote that gets business consultants very excited, it is fair to say that it’s also pretty relevant to sports photography. f Use a camera with the fastest autofocus you can afford. There’s a huge difference in tracking and focus acquisition speed between a consumer camera and a professional model. Perhaps that crucial game is the day you want to rent something fast. Just remember to spend a little time practicing with the gear first because the handling characteristics will be different than what you’re used to.

▲ To get the blurring of the background, I panned the lens, tracking the horse as it galloped by. To maximize the time exposure I used a low ISO setting and a very small aperture. 84mm full frame. f/22, 1/8 sec. ISO 50.

 In 2007 the Tour de France, the biggest annual cycling race in France, held its prologue and first stage in Britain. Hyde Park, London, England. 300mm, 1.6x crop. f/5.6, 1/500 sec, ISO 200.

4.7 Traveling light Generally, the key to successful travel photography is traveling light and staying flexible. So, while some people are happy to lug around heavy bags with two cameras and four lenses and a tripod, most people find it easier to stick to a single camera and lens. Accordingly, a lot of people find that the flexibility of a zoom lens is the best bet for general-purpose travel photography. The enforced discipline of a fixed focal length, while perhaps an interesting creative exercise, is

generally a bit limiting for travel situations. And carrying a bag of lenses, swapping them out as necessary, is few people’s idea of good fun.

If your camera lacks in-body stabilization, a lighterweight stabilized lens is also very handy. There are many instances when stabilizing can make a big difference, especially in low-light conditions. The ideal, of course, would be a fast lens, but fast zooms tend to be somewhat large and bulky. In terms of focal length, the traditional range of about 24mm to 105mm on a 35mm camera is usually a good compromise. If in doubt, it’s best to err on the side of wide rather than long for most travel photography. As described in section 5.7, zooms with massive focal length ranges are often too compromised to be really useful.  Various travel shots: • Hotel Everland, Paris, France. • Beaty Biodiversity Museum, Vancouver, British Columbia, Canada. • Bar at dusk, Oia, Santorini, Greece. • Hohenzollern Bridge, Cologne, Germany.

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4.8 The reporter’s triumvirate Photojournalists (PJs) have to be ready to cover any eventuality, and their work has always tracked technology closely. In the 1940s and ’50s they may have carried Speed Graphics with big dish-shaped flash units. In the ’60s and ’70s they may have used Nikon 35mm cameras. But today most PJs shoot digitally.

And while each PJ may have different tools and needs, there is one fairly common photographic model: carrying three sturdy fast zoom lenses that cover a full range of popular focal lengths. These lenses are typically a super-wide-angle zoom, a standard zoom, and a telephoto zoom. Journalists require highly rugged and reliable lenses and often shoot under very low-light conditions. They need rapid ultrasonic focusing and image stabilizing. Major lens makers such as Canon and Nikon cater to this professional market by selling weather-sealed zoom lenses with maximum apertures of f/2.8 across the focal length range.

 Canon’s 16–35, 24–70, and 70–200 L series lenses, with a pro-level EOS 1D mark IV camera. All three lenses have constant apertures of f/2.8.

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For Canon EOS, a typical trio would be the 16–35 2.8L, 24–70 2.8L, and 70–200 2.8L. For Nikon, the trio would be the AF-S 17–35 2.8D IF-ED, the AF-S 24–70 2.8G ED, and the AF-S 70–200 2.8 VR II. For quality pictures under tough conditions, these lenses are hard to beat. Many war photographers use this type of lens, for example. But they do have two notable drawbacks: They tend to be large and heavy, and they cost a lot of money. Accordingly, some lens makers also make similarly configured lenses that open up to only f/4, for significant cost and weight savings.

4.9 Low-light and night photography Most people put their cameras away when it gets dark, or else they fire up the flash. This is a shame because a lot of beautiful and evocative shots are possible under low-light conditions. Successful low-light photography is dependent on maximizing the amount of light recorded by the film or sensor. It’s always possible to crank up the ISO or use faster film, but that also increases the amount of noise or grain and may not be suitable for contemplative photos. However, grainier shots can work very well for more dynamic pictures, such as concert photos.

▲ Thomas Dolby (right) performs at the legendary Union Chapel. He’s joined by megaproducer Trevor Horn (left) on bass. Islington, London, England. 40mm full frame. f/2.8, 1/30 sec, ISO 1600.  Ant Hatcher of the Original African Indianz in concert at the Shunt Lounge and Theatre Company. London Bridge, London, England. 75mm full frame. f/2, 1/20 sec, ISO 800.

▲ This pair of lenses has nearly identical specifications. The only difference is one has a maximum aperture of f/2.8 and is thus larger, and the other has a maximum aperture of f/4 and is much smaller and cheaper.

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The primary tools of the night photographer are thus the tripod and the fast lens. Nothing beats a rock-steady platform for photography, even tools like image stabilizing. Stable platforms mean that long unblurred exposures are possible. And the longer the exposure, the more light hits the film or sensor.  The abandoned Cistercian abbey of San Galgano, Tuscany, Italy. 21mm full frame. f/5, 270 sec. ISO 200.

▼ Big Rig Jig, an art installation by Mike Ross consisting of actual 18-wheeler tanker trucks welded together. Burning Man arts festival 2007. Black Rock Desert, Nevada, USA. 40mm full frame. f/8, 15 sec. ISO 100.

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Still, long exposures can be somewhat tedious and inconvenient, and so faster lenses can be a huge time-saver, simply because they let in more light. It takes 1/8 the time to shoot with an f/1.4 lens wide open than with a zoom lens that only goes to f/4 ( f/4 to f/2.8 is a halving, then f/2.8 to f/2.0 is a halving, and finally f/2.0 to f/1.4 is half again).  Budavári Labirintus, the Labyrinth of Buda Castle. “The Axis of the World,” an art installation, now sadly closed, in the warren of ancient tunnels that run below the old city of Buda, Budapest, Hungary. 17mm full frame. f/4, 30 sec. ISO 200.

▼ The night sky above the Allen Telescope Array (ATA) operated by the SETI (Search for Extraterrestrial Intelligence) Institute. Hat Creek Radio Observatory, Hat Creek, California, USA. 17mm full frame. Digital composite of some 180 separate exposures, covering about an hour and a half.

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4.10

Wildlife photography

Ah, those amazingly inspiring nature society calendars and wildlife documentaries! Sunlight glinting off the tiger’s whiskers as it crouches to drink from the mountain brook! The intense concentration of the arctic fox as it prepares to pounce on the burrow of the hapless field mouse! The talons of the raptor extended as it plunges out of the sky … All amazing photos, and surely not that hard to take? Well, I don’t want to sound discouraging, but wildlife work is one of the more challenging types of photography out there. Photographing wild animals involves incredible technical precision, huge amounts of patience and persistence, and mostly, very expensive gear. The basic problem is that most animals are justifiably rather frightened of humans. It’s difficult to find the critters, get close to them, and record a fast-moving and uncooperative subject. Professionals build blinds (camouflaged tents) and stake out the bird’s nest for weeks with thermoses of coffee and a finger on the shutter release. They study the habits of their quarry and hire experienced local trackers. They set up remotely triggered cameras and portable robotic vehicles cunningly disguised as rocks, logs, or elephant dung. They trek into the backwoods with monstrous 600mm lenses and heavy tripods. In short, it’s difficult to summarize your best options for this type of work, as it’s so complex and variable. But in most cases, fast and long lenses are commonly used, unless tame or captive animals are your subject, as below.  Captive great grey owl (Strix nebulosa) at the Birds of Prey Centre, Old Warden Park, near Biggleswade, England. 100mm full frame. f/2.8, 1/80 sec. ISO 200.

 Dragonfly. Sidi Bouhel, Tunisia. 120mm 1.6x subframe. f/6.7, 1/500 sec. ISO 100.

▲ A captive king vulture (Sarcoramphus papa) at the Donjon des Aigles bird centre, Beaucens Castle, High Pyrenees, France. 205mm, 1.6x subframe. f/5.6, 1/125 sec. ISO 800.

▲ This photo was taken approximately 1.2 seconds before this thieving varmint of a coyote grabbed the memory card wallet next to my computer and ran off with it—with all my cards inside! Fortunately, about a minute earlier I had just finished backing up all my photographs to my laptop, so I didn’t lose any shots from a two-week shoot. Lawn of Scotty’s Castle. Death Valley, CA, USA. 105mm full frame. f/5.6, 1/200 sec. ISO 100.

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CHAPTER 5

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5

Choosing a lens by focal length

In most cases, the required field of view dictates the lens that is needed. This chapter describes the basic focal length categories.

5.1 Wide angle Wide-angle lenses are basically any lens with a field of view wider than a standard lens. On a 35mm film camera or full-frame digital, this is any lens with a focal length of 35mm or shorter. Wide-angle lenses are great when you need to take in a lot of a scene. This could be a dramatic shot of a landscape or a picture showing the interior of a room. Wide-angle lenses vary wildly in price, with the focal length the primary factor in determining cost. Focal lengths close to normal—28mm to 35mm for full frame—tend to be affordable simply because such lenses are easy to produce. But the wider you go, the more the light has to be bent and the more complex the optics have to be.

 The Uffizi Gallery, looking toward the Palazzo Vecchio. The Uffizi is one of the oldest art galleries in the world, and packed with Renaissance masterpieces. Florence, Italy. 24mm full frame. f/8, 4 sec. ISO 100.

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 The Thames Barrier, a giant movable barrier on the river Thames, which protects the city of London from tidal flooding. Greenwich, England. 28mm full frame. f/10, 1/200 sec. ISO 100.

 Mono Lake, a briny endorheic lake that has no outlet—water leaves only through evaporation. The silhouetted structures are tufa rock towers, which form underwater at hot springs. They’re only visible today because water demands from the city of Los Angeles caused lake water levels to drop. The nearly two-minute exposure has turned the stars into short lines and smoothed the water surface. Mono County, California, USA. 24mm full frame. f/7.1, 109 sec. ISO 100.

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5.2 Extreme wide angles Extreme wide angles—wider than 24mm or so for full-frame—can take in more than can be seen by a single glance of the human eye. A shot taken with an extremely wide-angle lens can also have something of an immersive quality. Since much of a scene can be within the depth of field, objects across the whole scene can appear very sharp. As described later in section 5.9, portraiture with these lenses can take on a strange bulging and grotesque appearance.

▲ When used for close up portraiture,

▲ An extremely wide-angle lens was needed to photograph this staircase in

wide-angle lenses comically emphasize

the Ruhr Museum, Zollverein World Heritage Site. Design by Dutch architect

the nose. For more information as to

Rem Koolhaas OMA. Essen, Germany. 16mm full frame. f/4, 2 sec. ISO 200.

why it’s not the lens causing this effect, see section 5.9. And to see this same model shot with a more flattering lens, see page 126. 16mm full frame. f/5.6, 1/100 sec. ISO 100.

▲ A Nikon D3x full frame camera with a 14–24mm extreme wide angle zoom.

These visual qualities are exploited by filmmakers such as Terry Gilliam, who is well known for his use of wide-angle rectilinear lenses (not fisheyes). People sometimes refer to 14mm cinematic lenses as “Gilliams” for this reason, though note that the image area of 35mm movie film is actually about the size of an APS-C subframe DSLR, and not the size of a full-frame 35mm still camera. Although they can yield striking photographs, wide-angle lenses can also be difficult to use well. Since they take in so much of a scene, photos can appear cluttered or busy or lack a main point of interest. Extreme wide angles tend to be very costly and often suffer from very soft or even blurry image corners. SLR wide angles must have retrofocus optics, which is a significant reason for the expense (see section 8.2).

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▲ This amazing craft is Clément Ader’s

5.3 Fisheyes

Avion III, an experimental steampowered aircraft from 1897. Unlike the

Fisheye lenses are a very specific form of wide-angle lens. Unlike rectilinears, fisheyes don’t try to keep straight lines straight. Instead, they demonstrate extreme uncorrected barrel distortion. Lines that happen to pass through the very center of the image will record as straight. All other lines will appear to bulge outward. There are two basic advantages to fisheyes. First, they can take in massive amounts of a scene, and second, the curving look can yield interesting visual effects. The primary drawback is related to the second point—not everybody likes or appreciates the classic fisheye look. The lenses can also be difficult to use, both aesthetically and practically. For example, it’s all too easy to get your feet, your shadow, or tripod legs showing up in a fisheye shot.

boring box kites of the Wright Brothers, which were superior only in the sense that they actually flew, this truly awesome-looking machine never really managed to get off the ground. Oh, well. Escalier d’honneur, Musée des Arts et Métiers (Grand staircase, Museum of Arts and Crafts), Paris, France. 16mm full frame rectilinear lens (not a fisheye!). f/5.6, 1/10 sec. ISO 200.

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 The Royal Albert Hall’s blue discs are part of the building’s acoustic system. This huge elliptical concert hall is far too large to be taken in one shot by anything other than a fisheye. Royal Albert Hall, during a BBC Promenade (Proms) concert, 2011, London, England. 16mm fisheye, full frame camera. f/8.0, 25 sec. ISO 100.

 Whoa, trippy. The lower section of the grand staircase of the Palais Garnier opera house, Paris, France. Built in 1875, this encrusted building is famous for being the precise opposite of restraint and subtlety. It’s also the setting for the dramatic musical The Phantom of the Opera. By putting the camera on a step and pointing a circular fisheye upwards I was able to capture a strange and disorienting view. The main challenge was staying out of the frame. 8mm circular fisheye, full-frame camera. f/9, 3.2 sec. ISO 100.

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 This shot of London’s Natural History Museum was taken with a full-frame fisheye. It reveals the ground floor beneath the pedestrian bridge, for a rather M. C. Escher–like view. 10mm fisheye, 1.5x subframe camera. f/16, 5 sec. ISO 200.

Including the sun in the frame is also hard to avoid and can result in a lot of lens flare. The bulging front glass element is also easy to scratch and damage inadvertently (see page 141). You can’t use front-mounted filters because of the protruding glass, and hoods are useless because they’d end up showing up in the frame. SOMETHING FISHY Fisheyes didn’t gain their name because of the bulgy eyes of fish. According to lens designer and photographic historian Rudolf Kingslake, the name was coined by American physicist R. W. Wood (of the “Wood” effect in infrared photography). The reason is that a fish, looking skyward from its watery domain, would see a similar effect because it would be looking from water to air. The first actual fisheyes were produced in England in 1924 by Beck of London and were called “sky lenses.”

Full-frame fisheye There are two basic types of fisheye lens, categorized by focal length. Fullframe fisheyes take in a full 180 degrees of the scene when measured diagonally across the frame. They’re basically as wide as you can possibly get without getting dark areas in the corner of the picture. These lenses have focal lengths of 15 or

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16mm when designed for full-frame 35mm cameras and around 10mm for subframe cameras. 15mm and 16mm full-frame fisheyes, when used in cropped cameras, just act as moderately wide-angle lenses, with only a little fishiness visible. Note the potential for confusion here, as “full frame” refers to the ability of the lens to cover an entire image frame of whatever camera is being used, not whether the sensor is the size of 35mm film or not.

Circular fisheye Circular fisheyes are the most extreme wide-angle lenses available. Most take in an amazing 180 degrees of the scene when measured across the short dimension of the image frame. This means that, when pointed up vertically, they can take in the entire sky.  Look up. Look wayyy up. The Eiffel Tower, seen by a circular fisheye. Note the blue coloration at the edges of the image caused by chromatic aberration. 8mm circular fisheye, full frame. f/5.6, 1/125 sec. ISO 100.

▼ Not an easy lens to use or carry—a weighty 2.4 lb (1 kg) Nikon 8mm fisheye from 1977. The projecting lower section is a rotating turret that contains internal filters.

Because of the extreme coverage, however, circular fisheyes record large black areas with a circular image in the middle. In other words, the entire image circle is visible in the frame. Circular fisheyes have a focal length of about 8mm on a full-frame 35mm camera. IT’S RIGHT BEHIND YOU The craziest fisheye ever produced was the Fisheye Nikkor 6mm 2.8s of 1972. This 236mm/9.3-inch diameter behemoth had a field of view of 220 degrees, which means it could actually see behind itself! Very few were made.

Fisheye zooms Most fisheyes are fixed focal length, but a few makers—Pentax, Tokina and Canon—produce zoom fisheyes.  Pentax 10-17mm fisheye zoom lens.

The Pentax and Tokina 10–17mm 3.5–4.5 lenses are designed to produce full-frame effects on a subframe DSLR sensor. The Canon 8–15mm lens is different in that it can be adjusted from circular to full-frame coverage settings for creative effect just by rotating the zoom.

Defishing Since the fishy quality of a lens follows straightforward optical geometry, it’s actually pretty easy to use a computer program to correct for fisheye barrel distortion. This lets you use an inexpensive fisheye lens as a sort of poor person’s rectilinear wide-angle lens. The process results in heavy loss in quality in the corners because you’re stretching the image most in the areas where the lens has its worst quality. Therefore, a lot of cropping is needed, and so the defished image will have a decreased field of view.

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▲ The capitular hall of the abandoned abbey of San Galgano,

▲ An automatic software program corrects for much of the fish-

Tuscany, Italy. A meeting area for the Cistercian monks who

eye barrel distortion, but it isn’t perfect.

once lived here. This fisheye shot takes in the whole room, but at the cost of a lot of distortion. 16mm full frame. f11, 1/20 sec. ISO 100.

▲ The defished image, cropped to a standard 3:2 frame.

▲ Other tools exist. This is Photoshop CS6’s Adaptive Wide Angle filter, which lets you manually draw control lines, called constraints, that force the defishing to straighten out segments of the image.

 The image with manual correction applied and cropped. The hall probably now has straighter lines than when it was built in the thirteenth century!

5.4 Normal or the Nifty Fifty Way back when, in the 1960s and ’70s, most photographers had a very modest selection of focal lengths available to them. SLRs, when sold with a lens, generally included a 50mm prime. It wasn’t until the 1980s that zooms became affordable and thus became the standard kit lens of choice. Today, 50mm lenses for SLRs are still available. And it may sound surprising, but there are very compelling reasons why you might want to buy one if you haven’t already. This isn’t out of some sense of retro nostalgia, but due to some very practical facts. As lenses go, 50mm lenses are easy for manufacturers to build. With wide-angle lenses, you have to bend light significantly to record a scene. Same with a telephotos but the other way—you need to bend the light right down. But when a lens has roughly the same focal length as the length of the diagonal of the image frame (43.3mm on a 35mm SLR), then a minimum of optical gymnastics are needed. Regular 50mm lenses might have 5 or 6 elements, compared to 15 to 20 in a modern zoom. The technology to build 50mms dates back years, and all the common problems have been solved.

▲ A standard 50mm f/1.4 prime lens.

WHY 50MM ANYWAY? As noted, the most basic full-frame lens would have a focal length of 43.3mm because that’s the length of the diagonal of the image area of a 35mm camera. And in fact, a few lenses, such as the Pentax SMC FA 43mm 1.9, have precisely this focal length. However 50mm was used as the standard length for the original Leica I camera way back in 1925, and that sort of stuck.

 A Leica I(a) camera of 1926, with its noninterchangeable 50mm “Elmar” lens.

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▲ Looking back in time. This picture was taken using a 40-year-old manual focus 50mm f/1.4 lens attached to a modern digital camera (see chapter 9). It was shot wide open, the full aperture providing a really narrow depth of field. A powerful studio flash unit was used, which is why the ISO is so low. 50mm full frame. f/1.4, 1/100 sec. ISO 50.

In short, it’s really easy to make a 50mm lens with great optical quality and a huge maximum aperture—and do it very cheaply. It’s pretty common for lens makers to sell a fast 50mm f/1.8 lens, with crisp high-contrast image quality, for the cost of a nice dinner for two on the town. Of course, if you’re used to the easy flexibility of a zoom, using a fixed 50mm can be a challenging discipline. Certain shots—closeups of distant wildlife or dramatic wide-angle skies, say—are basically impossible. But other possibilities arise. Having to move around to capture the perfect view of a scene can actually help you become a better photographer because it forces you to concentrate on the composition of the picture. And all kinds of shoots suddenly become possible with a really fast lens. You can shoot handheld under surprisingly low-light conditions, such as at parties, and 50mm lenses are also ideal for fun experiments such as creative apertures (see section 9.8) and macro reversing (see page 157). Finally, 50mm lenses may be a bit long for general-purpose use on a subframe DSLR. Unless you want a short portrait lens, a 28mm or 35mm lens might be a better choice in that case.

 Canestrelli, an artisanal mirror workshop in Venice, Italy. Rows of traditional “witches’ eyes” convex mirrors on display. 50mm full frame. f/4.0, 1/4 sec. ISO 200.

5.5 Telephoto Telephoto lenses are essentially telescopes for your camera. They let you narrow down the field of view to photograph distant scenes. Telephotos come in a variety of lengths, ranging from 85 to 135mm lenses suited for portrait shots in a studio, to 200mm and longer lenses ideal for that perfect shot of a lion stalking across the savanna. And of course the price and size of the lenses generally skyrocket as the focal length increases. Like any lens, they can be either fixed primes or adjustable zooms, though the longer and faster lenses, of the backbreaking type favored by sports and nature photographers, tend to be primes.  A Sony telephoto zoom lens.

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 The long reach of telephotos is ideal for scenes too dangerous to approach too closely. Here a dust devil spontaneously rises up, fueled by the intense heat of the massive fire. Black Rock Desert, Nevada, USA. 200mm full frame. f/4, 1/200 sec. ISO 160.

 This view of Manhattan skyscrapers is a classic example of how telephoto lenses can seem to compress the distance between objects. New York, NY, USA. 200mm, full frame. f/7, 1/640 sec. ISO 200.

Long focal length lenses have an obvious practical application in that they make photography of distant things possible. But in addition to this simple matter of range, they have the effect of seeming to compress the distance between faraway objects, as described in section 5.11.

 Telephotos such as the 70–200mm zoom lens used in this shot are ideal for portraiture. 125mm, full frame. f/2.8, 1/125 sec. ISO 100.

 A short telephoto, here a zoom set to 105mm, isolates details of this Ferrari 458 Italia. 105mm, full frame. f/4, 1/60 sec. ISO 200.

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5.6 Super telephoto At any major sporting event these days you’ll see a phalanx of professional sports photographers gathered on the sidelines with monstrous lenses. These are often super telephoto prime lenses—extremely fast and extremely long autofocus lenses. They’re the sorts of lenses that let photographers for news magazines capture, in incredible detail, players on the field whooping in jubilation1 or grimacing in defeat. They’re also used by nature photographers tracking down that elusive shy creature in the bush. These are essentially hefty telescopes with cameras mounted on the ends. Generally, they’re so heavy that they’re only really used with tripods or monopods to reduce blurring and to save the photographer’s back. They can also benefit from image stabilizing. Super telephotos in the 300 to 500mm range are mostly portable, though fast versions (f/2.8 to f/4) can be quite bulky. However, past about 500mm and up, the lenses can become quite unwieldy. Sigma’s huge 200–500 f/2.8 lens, for example, weighs 35 lbs (15 kg). The monstrous Canon 1200 f/5.6L lens was a bit heavier and measured 83 cm, or nearly 3 feet long. And the gigantic Zeiss 1700mm f/4 looks like the engine nacelle of a spaceship and weighs an absurd 564 lbs (256 kg).

▲ Large lenses like this massive Canon 400mm 2.8L II require

▲ A Sigma 200–500 f/2.8 lens, on display at the Photokina

strong shoulders and a large wallet.

trade show in Cologne, Germany. The little thing hanging off the back is, of course, a camera.

1 Sports photographers even have a special word for this highly marketable moment: jubo.

▲ Two cyclists pedal their way through a billowing desert dust storm toward a massive wooden sculpture named Message Out of the Future. Built by the Uchronians at the Burning Man arts festival 2006. Black Rock Desert, Nevada, USA. 265mm 1.6x subframe. f/6.7, 1/500 sec. ISO 200.  All across Spain, 45-foot tall bull silhouettes can be found on hillsides and other prominent locations. These are Osborne bulls, originally advertising placards from the 1950s. This one, in Alfajarín, Zaragoza, looks like it’s right next to the ruined castillo, but in fact they are quite some distance apart, on separate hills. The long telephoto shot flattens the perspective. 200mm full frame. f/10, 1/1000 sec. ISO 100.

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 Telephotos are great for isolating sections of a scene for a more abstract view. Compare this shot of the Thames Barrier to a wide-angle scene, as seen in section 5.1. 200mm full frame. f/5, 1/250 sec. ISO 100.

5.7 Megazooms We’ve all heard the story from the salesperson, or seen the glossy ads: Never buy a lens again! This single lens will cover any photo you’ll ever take! The perfect lens for any situation! These are the common claims associated with lenses with extreme focal length ranges. They’re often described in terms of a multiplication factor. For instance, a lens that goes from 28mm through to 300mm might be billed as having a roughly 10x range.

 ▼ Both shots were taken from the same spot: the only difference was the focal length used. The Basilica di Santa Maria della Salute in Dorsoduro, Venice, Italy, demonstrates the alluring promise of megazooms. One lens can take you from 17mm on a 1.6x subframe camera (27mm full-frame equivalent) all the way to an amazing 270mm (430mm full-frame equivalent). The first shot shows you the building; the second shows you the crown of stars and lightning rod on the topmost statue.

So why not go for one of these? Surely it’s really convenient never having to swap out a lens? The reality is that these lenses tend to be optically very compromised. It’s just really difficult to build a lens with a massive focal length range, and so other priorities such as sharpness and lens speed tend to fall by the wayside. (You may note that the inevitability of optical compromise seems to be a bit of a theme to this book.) Manufacturers certainly sell high-end professional lenses with 10x ranges, and you can spend huge amounts of money on such products. But the average affordable megazoom sold to the consumer market isn’t going to come close to the optical quality of these pro lenses.

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And arguably there’s no point to such lenses. Because they’re really slow, especially at the long end, they tend to need very long shutter times to take sharp photos. A 300mm lens really needs a 1/300 sec exposure on a bright sunny day at ISO 100 according to the handholding rule (see section 3.7). The parent who brings a consumer-grade megazoom to photograph little Sandy’s first sports game on a cloudy day is going to be pretty disappointed when they get home and see all the blurry pictures. Basically I advocate for zoom lenses with less extreme focal length ranges, at least if good image quality is important to you.

5.8 A matter of perspective One of the greatest points of confusion about selecting lenses of different focal lengths is the myth that your choice of lenses changes your perspective. The thing is, it doesn’t. The two key points are: f The position of the camera relative to the subject determines perspective. f The focal length (and size of the image area) determines the field of view.

Here the word perspective refers to the way a 3D scene is projected onto a 2D surface, recording size and position of each item. This may sound pedantic, but it’s actually kind of important for understanding which focal length is right for which shot. And two areas where it matters a lot are portraits and architecture.

5.9 Perspective in portraits You often hear that long telephotos take flattering portraits and that wideangle lenses take unflattering and distorted portraits. This is one of those things that’s kind of true. Or it’s true, but not for the reasons given. Apparent facial distortion is actually a matter of perspective. Distortion is thus caused by distance, not the lens itself. Consider the sequence of photos opposite. There are two factors that change between each shot: the focal length and the distance between the model and the camera. It’s the two factors changing together that confuses people into thinking that it’s the change in focal length that causes the bulging or flattering portraits, when it’s actually caused by the change in distance. Try this little experiment without a camera. Go up really close to somebody (preferably someone who knows you well) and examine their face closely. Since their nose will be sticking out close to you it will seem to dominate their face, while the rest of their face will seem further back.

16mm full frame. Deeply

20mm full frame. Quite em-

24mm full frame. Rather

embarrassing. Camera is

barrassing. About 1 foot from

regrettable.

6 inches from the model.

the model.

28mm full frame. Still not

50mm full frame. Just

70mm full frame. Looking

looking great.

slightly too close.

better.

100mm full frame. Looking

135mm full frame. Pretty

200mm full frame. Maybe a

good.

flattering as well.

tiny bit too far. About 13 feet from the model.

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The giant nose problem is exactly what happens if you use a wide-angle lens for portraiture. In order to get a person’s face to fill the frame when using a wide-angle lens, you need to get in really close, hence the grotesque distortion. Conversely, to get a person’s face to fill the frame with a telephoto, you need to be much farther away. To prove the point further, consider the two photos at the bottom of this page. One was taken with a 35mm lens and the other with a 100mm lens. But both shots were taken from exactly the same position. Naturally, one is a portrait with the face filling the frame, whereas the other reveals the studio backdrop where the shot was taken.  Taken with a 35mm lens on a full-frame camera. Area in white is shown cropped below left.

▲ The crop taken from the 35mm shot.

▲ Taken with a 100mm lens.

If you crop the wide-angle shot (the area not grayed out), the two portraits look almost identical, demonstrating how it is distance and not an inherent property of the lens that causes distortion. The only difference between the two shots is image quality—because the wide-angle shot is cropped and enlarged so much there’s a noticeable picture quality difference. So, in short, medium-long telephoto lenses are indeed ideal for portraiture. But this is because of the subject to camera distance required in order to use such lenses for full-face portraits.

5.10

Falling backwards: another take on perspective

Another area where perspective is especially important is architectural photography. It’s pretty common to hear that wide-angle lenses yield the “converging verticals” problem that makes buildings look like they’re toppling over backwards. Or that this is a classic case of “wide-angle distortion.” After all, in architectural work, you often want all vertical lines to be completely parallel.  The 1965 P&O Building in central London, across from the Lloyds offices, had a very unusual design. It had a central concrete core and floors were essentially suspended from the top. When it was demolished in 2007, as shown here, it was torn down from the bottom up. London, England. 17mm full frame. f/9, 1/180 sec. ISO 200.

In reality, converging verticals is another case of the distance to the subject being the basic issue, not the focal length as such. Take the view of the Custom House in Dublin, Ireland on the next page. The picture has the classic falling back problem. But the reason for this is simple: I was standing directly in front of the building at ground level, with the camera pointing upward. The distance between the camera and the front door is much less than the distance between the camera and the top of the dome. Therefore, the dome is further away than the door, and so it appears smaller.

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 A 17mm extreme wide angle, close up and looking up.

There are a few ways to minimize the issue: f Try a higher vantage point. f Move back and use a longer lens. f Use a tilt-shift lens (see section 8.24). f Correct the image digitally after the fact by stretching it (though this would be difficult to do effectively in an extreme example like this). In this case, I couldn’t try a higher point of view since the Custom House faces the River Liffey. I’d need to be aboard a crane on top of a boat. But by crossing the river, I was able to photograph the building again and obtain a much more natural perspective.  A 70mm telephoto, shot from across the river.

From this distant position the front door and the dome are now roughly the same distance away, even though I’m still at ground level. However, at this distance I needed a longer focal length lens in order to fit the building in. The first shot was taken with a 17mm lens, and the second with a 70mm lens. But again, the choice of focal lengths was dictated by my distance from the building. It was the perspective that yielded the falling back look.

 From ground level at the base of the building, the camera sees what appears to be a structure that’s tilting back.

 The ideal solution would be to take a photograph from midway along the building’s height. This is obviously impractical, though.

 Another solution would be to take a shot from farther away using a longer lens.

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Of course, converging verticals isn’t necessarily a problem. Often a photo can be enhanced by a dramatic converging verticals view.  Neoclassical architecture in Portland limestone. Air Street, London, England. 17mm full frame. f/6.7, 10 sec. ISO 100.

5.11

Compressed perspective

A common use for telephoto lenses is to compress a scene so that nearby objects and objects further away seem much closer together than they really are. Think of those shots of people walking down a Manhattan street in 1970s movies—they all look bunched up and crowded. This effect is also often held to be caused by lenses, but again it’s just a matter of perspective.  Dawn rises across the White Mountains. View from Schulman Grove, Ancient Bristlecone Pine Forest, Inyo, California, USA. This phenomenon of distant hills or mountains becoming lower in contrast is known as aerial perspective. 200mm full frame. f/4.5, 0.3 sec. ISO 100.

▲ Torii gates. Fushimi Inari Taisha shrine, Kyoto, Japan. Even though the gates were spaced quite a distance apart, the compressed perspective afforded by my 100mm lens makes them look all bunched up. 100mm full frame. f/11, 1.3 sec. ISO 100.

Imagine you’re standing 10 feet from one object and 20 from another. You take a photo. The distance between the two objects, assuming they’re in line with each other, is the same as the distance between you and the first object. Now imagine you’re 200 feet away from the first object. Now the 10-foot distance represents 1/20 of the total distance. If you photograph the scene with a telephoto lens, the objects will seem much closer together. Or take the view on the next page of the Millennium Bridge across the River Thames in London, England.

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▲ First, I took a picture with a 24mm lens. This wide-angle view takes in a sweeping amount of the scene.

▲ Next, I took another picture with a 200mm telephoto lens. Note how everything seems compressed together. But there’s an easy way to prove that it wasn’t the choice of lenses that caused the apparent compression.

▲ This third shot is simply the first shot, cropped. By taking a small section of the 24mm shot and cropping it down, I’ve got a photo identical to the shot taken with the 200mm lens.

The photos are identical because my position didn’t change at all, and so my perspective remained the same. The only difference between the shots is that the cropped picture is much fuzzier because of its lower resolution. Of course, arguably this is just fussing over terminology because if you photograph something a long way away with a telephoto, you’ll likely end up with the compressed perspective look. But I believe it’s important to understand the underlying reasons for the way things work.

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CHAPTER 6

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6  A six-point star filter was used for this portrait. The filter transformed the light from the modified flash unit strapped to the model’s hand into a starburst.

Accessorize!

6.1 Filters Filters are simple optical devices—typically flat discs of glass—that fasten onto a lens and alter its performance in some way. Most filters don’t magnify or otherwise change the focal length of the lens. They just perform basic functions, such as absorbing certain colors, and thus altering the overall color balance of the photo.

Threaded filters Most Asian-made lenses have fine threads on the end, letting you screw on a compatible filter. Filters come in a fairly standard range of diameters, though some sizes are more popular with some makers than others. Common filter diameters include 49mm, 52mm, 55mm, 62mm, 67mm, 72mm, 77mm, and 82mm. (Point-and-shoot cameras, if they have filter rings at all, may support 28mm or 37mm filters.) The diameters are often marked on lenses with the Ø symbol. It’s often handy to build a collection of lenses with the same physical filter sizes, to make mixing and matching filters easier.

 A plastic filter wrench is a useful tool for dislodging a jammed filter by applying even pressure around the perimeter.

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Filter rings tend to be made from aluminum. When used on a lens with an aluminum barrel, such filters can seize up and you may need a filter wrench to remove them safely. More expensive brass filters are available, though locking up is usually not a problem on modern lenses with plastic filter threads.

Step rings Simple metal rings can adapt filters to different-sized lenses. Large filters can fit over smaller lenses with a step up ring, though putting a smaller filter on a larger lens with a step down ring usually risks some darkening of the edges (vignetting; see section 8.19). The primary benefit of step rings is standardizing on a smaller set of filter sizes and lens caps. For example, if you’ve got two lenses with 77mm filter threads and one with a 72mm filter thread, you might add a step ring to the smaller lens. That way you only have to buy and carry around one size of filter. ▲ A step ring adapts a 77mm filter to a lens with a 67mm filter mount.

Filter height Filter rings come in different heights. Most are moderately shallow and don’t extend out very far from the filter mount on the lens. But some, particularly polarizers, can be quite tall. There’s a possibility of such a filter causing unwanted vignetting (see section 8.19) on some lenses.

▲ Regular and slim profile polarizing filters.

Most lenses accommodate standard filters, but some extreme wideangle lenses may require extra-slim filters to avoid darkening in the corners. The only way to know is to test the lens and filter combination you’ll be using. Some thin filters lack the raised ring to accommodate a normal lens cap, which is inconvenient.

Stacking

▲ Stacking multiple filters is never a good idea.

Most filters can be “stacked,” meaning they can be screwed together to combine filter effects. Generally this isn’t a good idea because each extra filter will cause image quality loss. But it can occasionally be useful to, for example, give a warming effect to a polarizer by stacking a skylight filter with a polarizing filter.

Other filter types Some European lenses use a bayonet mount (attach and rotate to click in place) for filters instead of a thread. These are mostly professional lenses from companies like Hasselblad and Rollei. There’s also the obsolete Series filter system that was used from the 1930s through 1970s. It had a range of threadless filters with sizes indicated by Roman numerals. However, the Series IX (or 9) size can sometimes still be seen with movie lenses.

Drop-in filters Some front elements are either extremely bulbous (fisheyes, wide angles) or really large (telephotos). Normal screw-mount filters would be either impractical or prohibitively expensive, and so such lenses often have rearmounted or drop-in filters. These are special filter mounts that use special slot-in rings midway down the body or have some type of mounting holder at the back of the lens.  A drop-in filter slot is located near the back of this telephoto lens. The thumbscrew is used to tighten the holder in place.

Gel filters Gels are thin transparent sheets. Originally made from animal gelatin (hence the name) but now usually made from polyester, gels are commonly used to change the color of stage lighting. High-quality gels can also be used as lens filters, usually in little rear-mounted holders.

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 Installing a flexible gel filter with a pair of tweezers to avoid fingerprints.

Since rear filter holders are extremely close to the film or sensor, it’s vital that the filter be as spotless and optically perfect as possible. Any dust, scratches, or creases will adversely affect the image.

UV filters Film emulsions are very slightly sensitive to wavelengths of ultraviolet (UV) energy that’s invisible to the human eye. Natural UV from sunlight can be recorded by the film, lending an unexpected haziness to landscapes.  UV-blocking clear filters.

Today this isn’t as significant an issue because most lenses and digital sensors block UV already. However, UV filters are commonly sold as protective filters since they are clear and have little effect on the image. Skylight filters are similar but tinted a light straw color. These filters color-correct for bluish light situations.

Protective and clear filters. A fairly controversial topic is that of protective filters. For one thing, clear filters in retail are a bit like supersizing your fries— you always get asked if you want to protect your investment with a clear glass filter when you buy a lens. These sales tactics make people rather suspicious of such filters. And so the question is, Are they worth it?  Here’s an example of why protective filters are a good thing. This UV filter nobly sacrificed itself that the lens beneath might live.

Protective/UV/NC (neutral color) filters are certainly a subject that arouses passionate debate among many photographers. It’s almost a religious question. Pros: f A clear glass filter will definitely provide some impact protection to the front of the lens. A sharp blow might crack a filter but save the far more expensive lens. f Clear filters can help keep dust, sea spray, rainwater, or windblown sand off the glass. In harsh conditions such as a dust storm, it may be preferable to sacrifice a filter than risk lens damage. Many weather-sealed lenses, in fact, are only fully weather sealed when a filter is installed. f High-quality filters with parallel surfaces, true optical glass, and multiple layers of lens coatings have relatively little impact on image quality. By definition they’ll always affect the image to some degree, but it should be negligible.

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Cons: f The supersized-fries filter is probably not going to be the highest-quality filter on the market, so it may be to your advantage to shop around for something better. f Another piece of glass in front of a lens is always going to affect the image. Horrendous image quality problems, such as upside-down reflections of bright areas of a photo, can be caused by cheap filters. This will be particularly pronounced in high-contrast situations, such as night photography. f A sharp blow to a lens can cause damage, filter or not. Internal elements can be knocked around, or the filter threads could end up being bent and locked to the end of the lens. f Good filters are expensive. A high-quality multicoated filter for a largediameter lens can cost as much as a cheap kit lens.  Here’s an example of a problem caused by a protective filter. The poorly-coated filter has resulted in an upside-down reflection of the brightlylit Trojan Horse sculpture. The Burning Man arts festival 2011, Black Rock Desert, Nevada, USA.

So, what about me? Do I use protective glass filters? The answer is yes, I do. When I’m outside I use high-quality multicoated filters (see section 6.1) and try to keep them as clean as possible. I want to protect my investment in lenses in terms of weatherproofing and impact resistance. However, when in the studio or doing a long night exposure, I often take the filters off.

Polarizing filters Light waves travel through both empty space and transparent material as waves of energy. The traditional metaphor, and I’ve seen it published as far back as 1940, is that of a rope tied to a post. If you take the loose end and wave it around, you’ll get random waves of motion rippling through the rope, much as ordinary light waves do.

Now imagine the rope is passed through a picket fence with vertical slats. All of a sudden the movement of the rope is restricted. Only movement in a vertical plane is possible. Just as our rope through the fence moves in a flat plane of motion, so can light. And the angle of this plane can be anything—horizontal, vertical, or in between. Now imagine another fence is added, but with horizontal slats. Rope motion that’s restricted to a vertical plane simply halts when encountering the additional barrier of the new fence.

It so happens that light reflecting from nonmetallic surfaces, such as water or glass, becomes polarized as though passing through our first fence. Light from the sky is also partially polarized. And polarized light is like our rope, moving in a single plane of motion.

▲ On the left, a shot with no polarizer. The blue sky is fairly pale, and reflections are visible in the windows. On the right, a polarized view. The sky is darker, and some of the reflections are reduced. Musée du Louvre, Paris, France.

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Polarizing filters can block polarized light of this type, as our second fence does. So, by using a polarizer, it’s possible to cut back the reflections from water or glass or darken a daytime sky. And, like polarizing sunglasses, the filters can also reduce glare in a lot of shots. Polarizing is a rare case of a filter effect that can’t be accurately simulated in software after the shot is taken.

Linear versus circular Traditional “linear” polarizers can interfere with the autoexposure systems used by most cameras sold since the 1980s. Accordingly, most polarizers sold today are “circular.” This means they contain an additional film of material known as a “quarter wave plate” that lets them work with modern cameras.

Neutral density filters Sometimes you find yourself shooting under very bright conditions. It’s then necessary to restrict the amount of light hitting the film or sensor—by reducing the shutter speed, decreasing the ISO, or using a smaller aperture setting. But what if you want a large aperture and don’t want an extremely fast shutter speed? One solution is to put a darkening filter over the lens, just like donning a pair of sunglasses. These filters are known as neutral density (ND) filters because they reduce the amount of light uniformly across the color spectrum. Good quality ones don’t introduce any color casts, though cheap crummy ones may tint the scene slightly.  Waves crash against a cliff in Vernazza, Cinque Terre, Italy. An 8x neutral density filter and low ISO were used to enable a full 25-second exposure in daylight to blur the waves into mist. 40mm full frame. f/22, 25 sec. ISO 50.

ND filters are useful for photographing nature scenes with extended shutter speed times. They permit unusually long shutter times in daylight, resulting in the characteristic “bridal veil” waterfall look, the slate-smooth surface of a lake, or the misty appearance of crashing waves. They also permit portraits to be taken with large apertures for a narrow depth of field. Different manufacturers name their ND filters in different ways, with the following being common. The bigger the density number, the darker the filter (0 being clear). ND name

Density

Stop reduction

Light transmission

ND2

0.3

1

50 %

ND4

0.6

2

25 %

ND8

0.9

3

12.5 %

ND16

1.2

4

6.25 %

Graduated neutral density (GND) filters The GND is a special kind of neutral density filter, darkened at one end and clear at the other. There’s a smooth transition zone between the two ends. The filters are often rectangular, so you can slide the filter up and down to adjust the transition point in the photo. Better filters are glass; cheaper ones are plastic resin. These filters are commonly used by nature photographers who have to deal with extreme variations of brightness in a single image. For example, at sunset the sky will be very bright but the ground very dark. This difference may be too much for the dynamic range of the film or image sensor to accommodate.  Graduated ND filters come in varying intensities. Also, some have sharp and others have soft transition lines between dark and clear.

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▲ The sun sets over the Aegean, Mykonos, Greece.

▲ The same scene with a graduated neutral density filter.

300mm full-frame. f/5.6, 1/320 sec. ISO 100.

By installing a graduated neutral density filter, you’re essentially “holding back” the sky by darkening it. This provides for better exposure of both the sky and ground, at the cost of longer overall exposure. The effect can be simulated digitally by taking multiple photos at different exposure levels, then combining them in a computer for a high dynamic range (HDR) shot.

Color filters All kinds of color-shifting filters exist. They work by absorbing certain frequencies of light and only passing other frequencies. This allows them to take white light and output different colors. This also means they can’t, for example, take blue light and output red light; they can only remove color from white, not shift colors along the spectrum. They can be categorized in three basic groups: color-correction filters, black-and-white filters, and special-effects filters.

Color-correction filters

▲ By blocking green and blue light, this filter colors everything red, because only reddish light can pass through. By definition this also means that using the filter costs light. Color filters easily cause a stop or more of light loss.

Warming filters are yellowish in tone and correct bluish light by making it seem whiter. They’re commonly used for warming up shots on overcast days or for shooting in daylight with film designed for tungsten light. Cooling filters are blue in tone and do the reverse. They’re used for shooting indoors under tungsten light using film designed for daylight. There are also specialized filters for removing the ugly greenish color casts caused by fluorescent lights, by adding a magenta cast. While essential for film, color-correction filters are less useful for digital cameras, which have extensive control over white balance.

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The before shot: a color

The same model, as seen by

A yellow filter makes the skin

An orange filter emphasizes

photograph.

traditional black-and-white

appear lighter.

the effect, minimizing skin texture and thus blemishes.

film chemistry. No filter.

A red filter lightens the skin

A blue filter darkens the skin

Green works well on a model

still further, but the red lip-

considerably, highlighting

such as this, who has un-

stick almost vanishes.

the tiniest blemish, and also

blemished skin, but can

darkens the red lipstick.

emphasize texture.

Black-and-white filters These are colored filters for use with black-and-white film. Essentially, they emphasize or de-emphasize certain colors when shooting monochrome images, allowing for greater tonal separation. A red filter, for example, can make a blue sky appear almost black, for high contrast with white clouds. It can also make a person with pale skin appear alabaster. By contrast, a green filter will emphasize skin ruddiness

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and texture (popular for characterful photos of rugged old men) or make red lipstick seem very dark. Such filters can be used with digital cameras, but the same filtration effects can be applied conveniently and nondestructively after the fact using software.

Filter names There aren’t any universal standards for filter naming, though variants of the Wratten and German systems are common. The British Wratten company came up with a bunch of arbitrary alphanumeric codes for various types of filters, and these are still used in Englishspeaking companies today. In this system, red filters are 25, warming filters are 81, and cooling filters 80. Darker variants may have letters, so you see 81A or 80B filters. German manufacturers often use codes such as KB to refer to cooling (blue) filters and KR for warming (orange) filters.

Special-effects filters This is a catchall category encompassing everything from bright lurid color filters to star filters. Most filter makers produce effects filters, but French maker Cokin, now a subsidiary of Japanese optical manufacturer KenkoTokina, is best known for the genre. Cokin makes large rectangular or round plastic filters that slot into matching holders.  A Cokin P holder and graduated filter. This filter would normally be used the other way around, of course, with the dark end toward the top to darken the sky. Keen-eyed viewers will note that the filter holder only has one set of slots. Normally Cokin holders have three, but I never use more than one uncoated rectangular filter at a time, and the projecting slots can cause vignetting with wide-angle lenses. So I cut the outer slots off with a hacksaw.

 This cheesy shot was taken with a multi-image filter for retro ’60s good looks. Lizard sculpture by Antoni Gaudí. Park Güell, Barcelona, Spain.

Such filters were popular with hobbyists in the 1980s because they enable all kinds of wacky and crazy visual effects. If you want a tobaccostained sky, or a hot fuchsia sunset, or a simulated motion blur effect, these disco filters are for you! Today the fun of goofy filters has largely been supplanted by the equally goofy fun of software filters applied inside a computer in post-processing. Software filters have the added bonus of being reversible and infinitely flexible, whereas optical filters fastened to a lens will alter the recorded image forever. A few other makers sell similar rectangular filters, sometimes using the same sizing system as Cokin (A for small and P for large) and sometimes using their own sizes. Professional filters, such as optically clear graduated neutral density filters used by landscape photographers, are sold this way.

▲ Pentax zoom lens equipped with a sizeable lens hood.

6.2 Lens hoods Hoods (or shades) are tubes or rings that fit over the ends of lenses. They might seem like they’re just there to impress beginners by making the lens look very long, but they actually serve two important functions. First, they block stray light from hitting the lens surface; light that can cause inadvertent lens flare (see section 8.15) and reduce contrast. And second, they serve as a form of physical protection to the front glass elements. Some lenses, particularly macro such as the one shown here, have recessed front elements and don’t really need hoods. But most lenses with exposed front elements can really benefit from a hood despite the extra bulk.

▲ A macro lens with a deeply recessed lens may not need a hood.

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Hoods come in different lengths. Telephotos can take longer hoods than wide angles, which have a wide field of view. Fisheyes and extreme wide angles can’t use tall hoods, which would appear in the shot. They may merely have a rudimentary raised ridge, such as the one on this fisheye lens. Filmmakers and videographers use large rectangular hoods known as matte boxes, which are equipped with movable “barn door” panels. ▲ A low, raised rim around a fisheye lens serves as a basic hood.

Model-specific hoods Most manufacturers produce specific “dedicated” model hoods for each lens they make, and they are designed for specific coverage requirements. These metal or plastic hoods usually have clip-on or bayonet mounts that attach to the end of the lens barrel. They’re usually not interchangeable, but occasionally a hood for a wideangle lens from a given maker might happen to fit a midrange lens by the same company. The drawback, of course, is that the wide-angle hood won’t have as much coverage at the longer end of the range.

▲ The black edging is what happens when you grab a petal-shaped hood designed for a midrange zoom and put it by mistake onto a wide-angle zoom that happens to use the same hood mount.

Pro lenses usually come with a hood, but annoyingly you often have to buy the hood separately for consumer lenses. Hood prices are absurdly high for what they are, so there’s a thriving market of third-party clone hoods.

FREE LENS HOODS FOR EVERYBODY If you’re on a really tight budget, you could even make your own lens hoods out of cardboard. Totally effective, though admittedly not very sturdy. Check out lenshoods.co.uk for details.

Hood shapes Dedicated hoods are usually shaped like slightly flared tubes or notched petals.  From left to right: a deep petalshaped hood, a very shallow hood for an extremely wide angle lens, and a tube-shaped hood.

Petal, sometimes known as “tulip” or “perfect,” hoods are designed with two longer sides and two shorter sides to give the maximum coverage for the rectangular frame with the minimum amount of weight. Petal-shaped hoods have to be lined up properly or else the classic two black triangles in the corners can appear.  Oops! The petal-shaped hood wasn’t rotated fully into position when this photo was taken, and the black corners are the embarrassing proof. Palais Garnier, Paris, France. 17mm full frame. f/5.6, 0.5 sec. ISO 200.

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Some hoods also have small notches, or “windows,” cut out at one end so you can reach in with a finger and rotate a polarizer filter if needed.

Generic hoods Generic hoods typically screw onto the end of the lens at the filter mount. They have the advantage of being interchangeable across brands, so long as the same filter diameter is used. You can usually attach a filter inside the hood, but at the risk of increased vignetting.

▲ A hood with a cutout for accessing a polarizer filter.

 A generic rubber hood: flattened for transport (left), and extended for use (right).

They’re often made of black rubber and can be squashed flat for storage. They can also be folded to various lengths to accommodate different lenses and reduce the problem of vignetting.

Flocking It‘s vitally important to suppress internal reflections within a lens. Heavy reflections can lead to flare, so lens makers take great pains to color all internal surfaces a matt black color. In some areas they even glue short black fibers to create a light-absorbing surface much like fine black velvet. This is known as flocking, and it’s a surface treatment used in the interior of many lens hoods as well.

6.3 Teleconverters and extenders It’s the budget photographer’s dream: a little device that can transform the focal length of a lens. Why carry around multiple lenses when a simple addon can modify the one you’ve got? That’s the promise offered by the optical accessories known as multipliers, extenders (Canon), or teleconverters (Nikon, Kenko, Sony, Tamron). So the obvious questions are, do they work and are they worth it? The answers are, like many things in photography, yes, but it depends. Teleconverters are lens-equipped tubes that fit between the camera and the lens. They effectively increase the focal length of a lens by a certain

factor. For example, a 1.4x converter will transform a 200mm lens into a 280mm lens. A 2x converter turns it into a 400mm lens.

▲ A Sony camera and lens with a teleconverter fitted between

▲ Canon and Nikon converters.

them.  The tiny speck near the bottom center is a photographer at work on the Death Valley dunes. An effective focal length of 280mm makes the distant mountains seem very close to the dunes. Death Valley National Park, California, USA. 200mm, full frame with a 1.4x converter. f/6.3, 1/320 sec. ISO 100.

Teleconverters essentially magnify the central area of an image. And this is the source of the major drawbacks of teleconverters: f If the lens is a crummy lens in the first place, a teleconverter just magni-

fies its flaws. f The greater the magnification of the converter, the more lens flaws will

be amplified and the blurrier the photo will be. This is why you don’t see, say, 10x converters. f Converters soak up light. An f/4 lens with a 1.4x converter, for example, will become an f/5.6 lens. f A slow lens with a converter will not be able to autofocus properly on many cameras. Typically, f/5.6 is a common AF threshold.

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f Many lens makers intentionally restrict which lenses their converters

work with. Nikon’s and Canon’s converters, in fact, only physically fit their professional-series lenses that have specially recessed rear elements. f For optical reasons, converters don’t work well with wide-angle lenses. They’re only typically used with 100mm or longer lenses. BUILT-IN At press time, there’s also one lens—the Canon EF 200–400 4L IS USM Extender 1.4x—that contains a built-in converter that can be enabled at the flick of a lever.

So, in short, a teleconverter is a great way to extend the reach of a highend zoom lens. But teleconverters are not magic bullets for all situations and all lenses.

6.4 Supplementary lens focal length adapters In addition to teleconverters, which fit between the lens and the body, it’s possible to buy supplementary magnifying filters that screw onto the filter mount. These change the field of view of the image, usually wider.  A pair of supplementary lens adapters. Both are designed to expand the field of view.

They’re common with point-and-shoot cameras for the simple reason that such cameras do not have interchangeable lenses. However, it’s rare to find such an adapter with great image quality. A common add-on is a “fisheye” attachment that transforms any modestly wide lens—say a 28mm lens for a full-frame camera—into a fisheye. These are simple glass lenses or, in the dirt-cheapest form, plastic.

The ones with magnification factors of less than 1 are wide-angle adapters. “Fisheye” adapters often have a 0.42x factor (e.g., a 28mm lens would supposedly have the coverage of a 12mm lens). So. Do they work? Well, yes, especially if the host lens is stopped way down and not left wide open. But typically you get pretty blurry images with tons of chromatic aberration and awful corner sharpness. The basic problem is you can’t make such an add-on filter to high optical standards and have it be affordable as well. If you just want a cheap toy to play around with, they’re good fun. But if you want to take decent photos, you’re better off investing in a real lens.  The disused platform at Aldwych, an abandoned tube station on the London Underground system. A lens attachment was used to take in the full view, but the quality of the resultant image is quite low, especially around the edges.

6.5 Macro accessories Macro photography, as discussed in section 4.5, is a fantastic way to explore the miniature world around us. There are many add-on tools to make macro work possible.

Extension tubes Extension tubes, or extension rings, sound like an incredibly amazing deal. Instantly transform your lens into a macro lens for peanuts! And then you open the box to find a simple hollow plastic tube containing nothing but air. Can it possibly work? Well, the answer is yes, extension tubes can work extremely well at shortening the close focus distance of a lens. In fact, the shot on the next page was taken with a simple extension tube. But there are certain caveats.

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 Extension tubes come in a variety of lengths, from around 12mm to 36mm. The longer the tube, the greater the magnification and the greater the loss of light. Tubes can be stacked, though longer tubes may not work with some wider-angle lenses.

Extension tubes are simply tubes with mounts on each end, which fit between the camera and the lens. They look like teleconverters, but have no lens elements and don’t alter focal lengths at all. Instead they increase the magnification of the image. And since they don’t contain any glass, they don’t degrade the image. They don’t have to be used solely for macro work: a tube in conjunction with a typical 70–200 zoom can be useful for tight portraits, for instance.  Ordinary garden snails make for great macro subjects. They’re completely strange and alien looking, and of course their slow movement makes them very easy to photograph.

Tubes may not be the last word in convenience, but they are a fantastic low-cost way to get into macro photography. Throw a tube or two in your camera bag and you’re always ready to take a macro shot.

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Drawbacks of tubes Unfortunately, the further you move the lens away from the camera, the more light you lose. Tubes also cause the loss of infinity focus, but that’s not a problem for closeup work. Some extension tubes contain electrical contacts, allowing a chipequipped lens to communicate with the camera. Those that don’t will disable automatic exposure, auto apertures, and so on. In-body autofocus motors also can’t work through a tube. However, autofocus frequently doesn’t work reliably with tubes anyway—you typically have to move the camera back and forth to focus. It’s worth checking a tube for compatibility because some older ones may not work with modern electronic lenses. Also, cheap tubes may not be sturdily built, and they may be incapable of handling the weight of a heavy lens. Collapsible macro bellows are similar to tubes, only they can be adjusted for length.

Closeup filters Another simple and portable way to take macro photos without a macro lens is the add-on closeup filter, or diopter, which is essentially a highquality magnifying glass that screws onto the filter threads of a lens. (Not to be confused with viewfinder diopters, which are corrective lenses that allow people who need spectacles to look through a viewfinder unassisted.) Diopters work, and don’t reduce light the way extension tubes do, but they also have their limitations. The stronger the magnification, the blurrier and less contrasty an image can become. It’s also wise to shop for a twoelement diopter because the single-element diopters tend to offer lousy image quality. Confusingly, there are different ways to describe the magnifying power of a diopter. Canon calls its diopters 250D and 500D, referring to focal length. This is equivalent to +4 and +2 diopters. Nikon assigns arbitrary numbers. Nikon #3T and #5T are +1.5 diopters, and Nikon #4T and #6T are +2.9.

Reversing rings One of the funny things about macro is that some lenses are great for close focus work—when they’re installed backwards. A typical 50mm lens, for example, can easily be attached to a camera using a reversing ring, which has a lens mount on one side and a filter mount on the other.

▲ An add-on +4 closeup filter for a small lens with a 49mm filter thread.

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 A camera with a reversed 50mm lens attached using a reversing ring.

All kinds of lenses will work for this. Even an old manual-focus 50mm lens that nobody wants anymore because it has an orphaned lens mount will work well, and it will probably be priced right. The technique required is a bit inconvenient and fiddly, though; in order to focus you have to move the entire camera. It’s also likely that, unlike with a true macro lens, you won’t have perfectly flat field of focus, so flat objects like printed paper may have focus issues at the edges.  An extreme closeup of the stamens of a lily flower, taken using the setup shown above.

For even greater magnification, it’s also possible to attach a reversed lens to the end of a regular lens, preferably a zoom so you can experiment with various focal lengths. If the reversed lens has a wide open aperture setting, then the depth of field will be incredibly narrow, as seen in this shot of lily stamens on the previous page. If you’ve got an old manual-focus lens, it should be possible to adjust the aperture by rotating the aperture ring. On a modern electronic lens, you may need to set the aperture, press the depth of field button to stop down the lens, then detach the lens while holding down the DOF button. This may keep the lens at the desired aperture setting.

Focusing rails The best way to achieve precise focus in macro work is usually to physically move the camera and lens. For this a dedicated macro rail—a rack and pinion with either one or two axes of motion—can be very useful. Twoaxis or cross rails allow for both forward/back motion and left/right movements. Rather than trying to drag a tripod across the floor, you just turn a knob to glide the camera forward or back.  An inexpensive two-axis focus rail for macro photography.

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6.6 Caps Many accessories are worth considering for any lens, but only one is completely essential: the ordinary lens cap. Lens caps are plastic or metal covers that protect the lens glass when the lens isn’t in use. They come in two flavors: the front cap and the rear. The front cap is designed to fit the lens in question. Normally this is standardized to the filter diameter of the lens, though occasionally it can be custom designed for an unusual lens, such as a fisheye, which lacks front filter threads.  From left to right: a rear lens cap, a front lens cap, and a body (camera) cap.

Most front caps are simple plastic affairs with side clips that you squeeze in to detach. The main variant has front-positioned recessed clips, which are easier to grab and release if a lens has a hood installed. The rear cap is universal to the lens mount in question and protects both the rear lens element and any electrical contacts on the barrel of the lens. They can also protect any protruding mechanical couplers, like the Pentax aperture mechanism.

6.7 Bags Lenses sometimes ship with small pouches or bags, which help protect the barrel from minor blows and scratches. There are also various interchangeable bag systems with complex waistbelt assemblies that some pro photographers use for carrying their gear. Or you could take the time-tested approach of stuffing the lenses into a small bag or satchel. As with many things, the best option is a personal choice.

6.8 Tripod mounts Most lenses hang off the body they’re mounted to, whether the camera is fastened to a tripod or used handheld. However, this can be a problem for really heavy or long lenses such as monster telephotos.  Huge telephotos always have lensintegral tripod mounts.

In such cases, it can be better to attach the lens to the tripod, letting the camera hang off the back. The body’s lens mount is always strong enough to support the camera’s weight. Very heavy lenses will have such tripod mounts built in. For lighter lenses, you can usually buy optional add-on mounts. But if no mount is available, then it’s a good sign that the manufacturer believes no such mount is necessary and it’s fine to attach the camera body straight to a tripod.

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CHAPTER 7

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7

Buying lenses

And now the difficult choices—what to buy, and from whom?

7.1 Camera brand or third party?

 Selfridges department store in Birmingham, England. 24mm full frame. f/8, 2.5 sec. ISO 100.

One of the key reasons camera makers like to design their own custom lens mounts, rather than collaborate on the creation of a cross-brand standard, is frankly to ensure sales of their own products at the expense of their competitors. For this reason companies encourage people to stick with only their brand of lenses and thus stay within the maker’s economic ecosystem.  Sigma makes a number of fisheye lenses to capitalize on gaps in the market. The Sigma 8mm lens (left) is a circular fisheye for full-frame cameras. The 4.5mm lens at far right (yes, it’s that short!) is a circular fisheye for subframe DSLRs.

However there are many lens-making firms that design lenses that are compatible with the top camera systems. These are often referred to as third-party manufacturers (you’re the first party and the camera maker is second). The biggest names in this field are the Japanese makers Sigma, Tamron, and Tokina. Some products are also rebranded. For example, in the United States, the Ritz Camera chain sells Sigma lenses under the name Quantaray. Korean Samyang products are available under at least three different brand names in certain territories: Pro Optic, Rokinon, and Bower. Of course, Zeiss-branded lenses are also third party. However they’re so incredibly expensive—much more costly than equivalent brand-named products—that they form their own rarefied category. They’re also manual focus only, and so essentially don’t compete with the autofocus lenses. Here are some pros and cons to third-party lenses:

▲ A pair of affordable third-party lenses.

Pros f Third-party lenses are often cheaper than their brand-named equivalents. Zeiss lenses are one notable exception, as mentioned. f Third parties sometimes make lenses that brand makers don’t. There may be a specific focal length that is otherwise unavailable. For example, Canon doesn’t make any 8mm prime fisheyes, leaving that market to third parties. Cons f A given third-party lens isn’t always of the same build and optical quality as the equivalent brand-named lens. This isn’t to speak ill of third-party products; it’s just that they tend to compete mostly on price and so other things have to give. f Third-party lenses can have long-term compatibility problems. They may work with today’s cameras, but that’s no guarantee they’ll work with future cameras with the same lens mount. Sometimes a lens maker will supply new computer chips or update lens firmware to allow for compatibility with newer cameras, but this is by no means guaranteed. f The user interface may be different from what you expect. Some thirdparty lenses have the same focus and zoom rotation directions (see section 3.9) as the original manufacturer; others don’t. f Because of real or perceived quality issues, resale values tend to be lower than for brand-named products. Again, Zeiss lenses are an exception.

▲ This Tokina wide-angle lens is available in a number of different lens mounts.

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7.2 Where to buy? All kinds of retail outlets sell cameras. SLRs and lenses aren’t sold just by specialty camera shops anymore. You can buy gear from big drugstores, online electronics retailers, department stores, and more. But where is the best place to go?

Traditional local camera stores Small camera stores are under a lot of pressure these days, and many have succumbed to online retailers and discounters. But a good local camera store is a fantastic resource. First, they’re often run and staffed by knowledgeable and enthuastic camera buffs. Staff may be a bit opinionated, but you know they’re not likely to be pushing a given brand just to make a sales quota. Second, you can actually try out the products they sell and decide if they’re for you or not.  Aperture Photographic in London, England. Not only is this shop staffed by knowledgeable experts, but its unusual in-store café is a social hub for local camera geeks.

The drawbacks are obvious. First, small stores tend to have higher prices because they have to maintain a physical storefront with limited stock turnover. They have to pay salaries to retail staff and pay local taxes, something online retailers can dodge in many countries. And second, they won’t have the range of inventory of a large superstore.

Large chains Camera chain stores are sometimes the only choice for people living in smaller cities. However, there are fewer and fewer of them because their traditional sales of point-and-shoot cameras are being undercut by other

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retailers, and one-hour printing is losing out to ink-jet printers and people viewing shots on-screen. For example, one major U.S. mall chain plunged from 1,200 stores in 2001 to 300 in 2011. Such shopping center stores have never been particularly useful for users of SLR systems, though they may have a small range of stock.

Pro stores Most larger cities have a store dedicated to supporting local pro shooters. They vary in size, basically depending on the size of the market, but offer a higher level of support than small camera sellers offer. Pricing tends to be higher, but you’re essentially paying for access to local knowledge. Some typical pro stores are Adorama in New York City, Samy’s in Los Angeles, Glazers in Seattle, Calumet in London and Chicago and other cities, and Vistek in Toronto.

Global superstores Major cities like New York and Tokyo boast massive photo and video superstores that carry an unrivalled range of inventory. A visit to B&H Photo Video in Manhattan with its network of automated conveyor belts, or Yodobashi Camera or Bic Camera in Tokyo with their cacophony of recorded ads, is something of a holy pilgrimage to the photographic devotee.

▲ Yodobashi Camera’s superstore in Shinjuku, Tokyo, Japan. Visitors expecting Zen-like tranquility are going to be disappointed.

Specialist online retailers Reputable online merchants typically offer good pricing, a huge selection of products, and easy browsing of catalogues. They’re also very convenient for people outside of major cities. However, unless you know specifically what you need before you buy, there’s the drawback of no prior physical access to the products. In the United States, B&H Photo Video and Adorama of New York (the latter allied with Amazon.) sell their entire product lines over the Internet. KEH of Atlanta specializes in a huge range of tested secondhand gear. In Britain, Wex Photographic (formerly Warehouse Express) carries a solid range of new gear from its base in Norwich. In Canada, Toronto-based retailers Vistek and Henrys also sell nationwide via their websites. Many other online sellers exist, but be very cautious before going with an unknown (see section 7.3).

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 Wex Photographic’s showroom in Norwich, England.

Generic online retailers Major online retailers like Amazon carry a range of products, often in association with smaller sellers. Prices and shipping choices are usually good, though they can’t always compete with the specialist online resellers when it comes to selection.

General-purpose stores Drugstores and department stores often carry a limited range of cameras in photo departments. On the whole, they aren’t a great choice for people serious about photography. Staff are rarely well trained, and the selection of products is limited. Pricing can sometimes be competitive if you know what you want though.

Auction sites

▲ Let’s hope that this lens-shaped mug is actually what you expected when you bought it, sight unseen, from a private seller.

Popular auction sites like eBay are great places to find obscure, used, or unusual products. However, there are a lot of risks involved with auctions. First, because of the high prices involved with most camera gear, there’s a serious risk of fraud. You probably won’t get ripped off buying a ball of yarn or a homemade hat online because the money involved isn’t worth the risk to the seller. But expensive camera gear is a different story. Second, I recommend never buying anything that’s still available new retail. A strange auction fever takes over (I – must – win!) and can drive pricing far beyond what an item is worth. In summary, with auction sites, do your pricing research carefully, use a credit card or escrow service, and never buy anything that is still sold new elsewhere. Similar risks apply to local classified ads. You might be buying an old unwanted lens that once belonged to Grandpa, or you might be buying something that was stolen last week from your neighbor.

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7.3 The dark side of camera retailing A quick perusal of the Internet may seem to reveal some amazing prices for lenses, particularly when compared to official list prices. But always remember the old adage: if it sounds too good to be true, it probably is. In particular, if a new lens is advertised to be dramatically below the price set by the most reliable online retailers, you should be very suspicious. Many unscrupulous retailers operate in a shady interzone, changing addresses, websites, and company names on a regular basis. This of course they do to be a moving target for the authorities. The less-reputable stores employ a number of cunning techniques to separate you from your hard-earned cash, ranging from unethical and deceptive tricks to downright illegal scams. Here are some common methods: f Removing an item included in the box with a product,

and either selling the product without it, charging a higher price for its inclusion, or claiming it’s a special “gift” to you. Popular tactic with kit lenses. f The old classic of “bait and switch.” This involves advertising one item but actually shipping you a different one. f A variant is to provide you with misleading or completely fraudulent information. For example, you may be told, “Oh, the lens we advertised for that price is the Chinese-made edition. If you want the version built in Japan, you need to pay a premium.” f Not maintaining adequate product inventory, charging your card when you order, then shipping the product at a later date. ▲ Hopefully this damaged lens came from a reputable dealer. f Shipping a version of the product intended for a different region. f Reselling used or customer returned products as new, especially if the product is faulty and you’re directed back to the manufacturer. This all sounds very scary. So how can you protect yourself and lower the risk? f Pay with a credit card. The cards may have their drawbacks, but credit

card fraud departments are powerful allies in the event of a dispute. f Know what’s a reasonable price and what isn’t. f Listen to the salesperson. It’s not worth trusting pushy, aggressive, or nasty salespeople with your money.

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f Research your buying options carefully. Look at websites that review

f

f

f

f

retailers to see if they’re legit. Look for lots of fake-looking recommendations. Visit websites like Photo.net, which has a “Neighbor to Neighbor” section where people can post horror stories and good experiences. Double-check the address of the storefront. For example, perhaps you see a lot of negative reviews for AAA SuperCamera International of 100 Main Street, and if the shop you’re considering is Princely Photos of 100 Main Street… Look up a picture of the store address in Google Maps with Street View or Bing Maps StreetSide. If you find that there’s no storefront and the alleged shop is somebody’s apartment or a warehouse in a very sketchy part of town, you might consider your options. For some reason, a lot of alleged shops appear to be based in Brooklyn, New York. Now I’m not suggesting for a New York minute that every single camera store in Brooklyn is fraudulent. (reputable Manhattan seller B&H has a warehouse there, for example), but I would look very carefully at any store with an address there. PCWorld Magazine and the New York Times have both published very informative investigative pieces on this subject, incidentally. Also check out hobbyist Don Wiss’s site documenting Brooklyn storefronts at donwiss.com. Pay no heed to the flashy logos of shields and check boxes and stars that purport to represent some sort of consumer standards stamp of approval.

7.4 Warranties An important factor when shopping for new lenses is the warranty. Because the cost of doing business varies from place to place, and because warranty expenses are usually borne by the local distributor or importer and not the manufacturer, warranty coverage is typically restricted to the region of purchase. This means that the camera you bought on holiday in New York may not have coverage in Britain. Or that lens you picked up for a song in Hong Kong may not have a warranty in San Francisco. Some makers even refuse to repair products bought outside their region for a fee, which can be a bitter pill indeed. This lack of warranty issue can occur if you buy a lens in another country, but it can also happen if you purchase a “gray market” product.

7.5 The gray market Gray market, also known as direct import, is the retail practice of importing a product directly from an overseas manufacturer, bypassing the local distribution company or authorized importer. There’s nothing inherently illegal about this. A large store located in a country where the cost of business is high (e.g., the United States or somewhere in Europe) might send its buyers to a country where the cost of business is low (e.g., southeast Asia). If all import duties are paid, then it’s usually legal to sell these products to customers. All the shop is doing is cutting out the manufacturerappointed distributor for its region. Respected New York superstores B&H Photo Video and Adorama are well known for direct import bargains that they support themselves. However, there are potential problems for the end customer—you. As long as the shop is honest and upfront, then it’s fine, much as manufacturers hate the practice. But there are potential risks: f You may not have local warranty coverage. Since the local distributor

doesn’t make any money off products that it didn’t import, it’ll probably refuse to service it, and your only recourse is to ship the product back to the store. As long as the store is reputable, this is probably fine, just inconvenient. f The manual may be in a different language, which could be an issue for a complex product like a camera. f You may be ineligible for camera software updates from the local distributor. f In the case of a device powered by AC, you may not get the correct power plugs for your region. f Sometimes the product may have a different name, though this is unlikely in the case of lenses. For example, the Canon EOS 650D camera in Europe is marketed as the Rebel T4i in North America and the Kiss X6i in Japan. f You aren’t supporting the local sales and distribution infrastructure for the maker in question. f You won’t be eligible for any distributor rebates.

7.6 Going used? New lenses are expensive. This makes the secondhand market very attractive. Unlike film cameras, which have depressingly low resale values, and digital cameras, which plunge in worth the moment they leave the store, lenses

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hold their resale value amazingly well. As long as the camera system they were designed for is still current, a lens is still completely usable. And if it’s not, you may be able to adapt it (see section 9.2). Accordingly, you may want to consider whether the risks of buying used outweigh the savings. Personally, I don’t buy used lenses that are still new in the maker’s lineup because the price will be too close to the list price. But I may consider older products if the price seems right. Generally, there are three things to consider when shopping for a used lens: f Can the lens still be serviced? Manufacturers maintain an inventory of

parts for only a number of years (sometimes as few as five) after the product is discontinued. If a lens fails after that point, it may not be possible to get it repaired. Ask the manufacturer’s service department if the lens is still supported. f Is there any obvious damage to the lens? Not all forms of damage are necessarily visible to the eye, but any signs of impact such as cracks to the barrel are worth avoiding because it could mean elements are out of alignment or focus motors are unreliable. If you have access to the lens, put it on your camera and take some test shots. Examine the pictures carefully for sharpness, especially at the corners. Do the rotating rings turn smoothly without binding? Do all functions work correctly? Does it sound normal in operation? A lens with heavy signs of abuse may have been used by a working professional, and it may have had a rough life. f Are you buying from a reputable dealer with a solid return policy or from a private seller or small store? You pay more for the former because it’s essentially a form of insurance if something goes wrong. Private sellers may charge less but then the risk is on you. As noted earlier, online auction sites and classified sites are particularly affected by fraud.

7.7 Rental options One significant advantage of choosing the same camera system as the professionals is that it gives you the option to rent. If you’re a hobbyist, you may not be able to afford a pro lens that costs three times as much as your camera. But you might be able to rent the lens for a weekend. This offers two great advantages. First, you can “audition” lenses you’re interested in. There’s no better way to learn if a product is the right one for you. And second, it gives you a wide arsenal of lens types at your disposal. You might need a fisheye only once a year, so why buy one?

 The rental counter at Fixation, a pro supply company in London, England.

Here are a few things to note about renting: f Check the rental company’s insurance policies. It’s painful to be on the

hook for the replacement or repair costs of a lens you don’t own. f Only certain brands are going to be available for rent. It’s easy enough to find Canon, Nikon, and Hasselblad rentals, but it’s less likely that Sony, Pentax, or Olympus gear will be available. f Because of normal levels of product variation, the lens you happen to rent is not guaranteed to have precisely the same performance as another lens of the same exact model. This phenomenon is described further in section 8.37. Of course, reputable rental companies will try to ensure that their line isn’t completely out of alignment. f Rentals are rarely available outside major cities. However, there are some companies that operate online and ship rentals by courier. Lensrentals.com is one such company, though it does not ship outside the USA.

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CHAPTER 8

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8

Advanced topics

8.1 Learning more about optics This chapter dives into the details of basic optics. You don’t have to know this stuff to take good pictures, but I believe that mastery of a set of tools requires some understanding of how it all works. And photography is a pretty technical field, which is why I’ve dedicated a fair bit of space to these topics.

8.2 What is focal length? In chapter 2, I described how focal length is a key factor in determining the field of view of a given lens. But focal length values aren’t arbitrary numbers.

What focal length isn’t There are many popular misconceptions. Focal length has nothing to do with the physical length of the lens, the distance between the back glass element of the lens and the film or sensor, the distance between the front glass element and the film or sensor, or a halfway point along the lens. It’s more complex than that.

Focal length of a simple lens

Lens

Film/sensor

Focal length

To start, think of a simple converging lens, like a magnifying glass. Incoming rays of light are captured by the lens, bent inward, and projected back out. The outgoing rays are focused down to a single sharp point called the focal point. The focal point is at the focal plane, which in the case of a camera is where the film or image sensor is located. In the case of a magnifying glass and a cruel child, it’s where the ant is. The point in the lens from which the outgoing rays of light appear to originate is known as the rear principal point. (Sometimes it’s called the rear nodal point, but that’s technically something else, though they do coincide in most camera lenses used in air.) In the case of a simple lens like this, the rear principal point happens to coincide pretty closely with the physical center of the lens. And so that’s the focal length: it’s the distance from the rear principal point to the focal point. There are a few other details to the definition, such

as the fact that the lens has to be in air (light behaves very differently underwater) and focused at infinity, but that’s the gist. Today, focal lengths are always measured in millimeters. Pre-1960s lenses sometimes used centimeters, and some antique lenses were measured in inches.

Focal length of a compound lens But what if you have a whole set of lens elements, as you do in the case of the compound lenses used in cameras? Where is the focal length measured from then? The answer is that it’s still measured from the rear principal point, only now this point won’t necessarily line up neatly with any particular part of the lens assembly. The point from which the outgoing rays of light appear to project can be pretty well anywhere inside the lens—or even outside it if the lens designer wants.  Here’s a lens diagram for a typical 50mm lens, which uses a popular “double Gaussian” design. The rear principal point is indicated by the dot. As you can see, it doesn’t really line up with any physical part in the lens assembly. Diagram generated by LensForge.

All this optical complexity means that there’s no easy way to tell the focal length of a lens just by looking at it. So lens makers calculate the focal length and print it on the barrel for our convenience.

Telephoto lenses The ability of a lens designer to specify the position of the rear principal point, by adding special groups of lens elements to the design, is incredibly useful. For example, take a lens with a focal length of 300mm. If the lens

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actually had to have 300mm (about a foot) of distance from the back to the focal plane, then you’d have a pretty long and cumbersome lens. Fortunately, modern telephotos contain special lens elements that allow the distance from the back of the lens to the focal plane to be less than the focal length. This allows for physically shorter and more compact lenses. The reverse is done with wide-angle lenses, as described in the next section.  This lens diagram demonstrates how the focal length of a Nikon 70–300 lens shifts. First, note how the different groups of lens elements move within the barrel as the focal length is changed. Second, note how at 70mm the rear principal point (the red dot) is located within the lens assembly.

Lens focused to infinity at 70mm

But at 300mm the principal point is actually located outside the front of the lens! This complex optical design makes the compact size of the lens possible.

Lens focused to infinity at 300mm TELEPHOTO OR LONG? Technically, any lens with a long focal length is a long or long-focus lens. And technically only long lenses with optics designed to shorten the back focus distance relative to the focal length are telephotos. However, most people casually refer to any long lens as a telephoto, whether or not it actually has a telephoto optical design, simply because nontelephoto long lenses are fairly rare these days.

Retrofocus lenses As established earlier, the shorter the focal length of the lens, the wider the angle of view. And short focal lengths require the back of the lens to be much closer to the focal plane. In the case of rangefinder and other mirrorless cameras, the rearmost lens element can be positioned quite close to the focal plane because the only thing that stands between the two is usually a thin mechanical shutter. However, in the case of an SLR with a mirror mechanism, clearance becomes problematic because of the swinging mirror assembly itself.

SLR

Rangefinder

 An SLR’s moving mirror limits how close a lens can be positioned to the film or image sensor. However, in a mirrorless camera or rangefinder the shutter (black line) is the only mechanical barrier.

Mirrors restrict how wide an SLR lens can be and so, in 1950, French maker Angénieux produced an ingenious optical design it referred to as retrofocus, or reverse telephoto. By using “negative” lens elements, the retrofocus design allows the distance between the back of the lens and the film or image sensor to be longer than the focal length (i.e., the rear principal point is moved outside the lens assembly itself, and may be located in space). This breakthrough allowed for the moving mirror assembly to fit and made wide-angle lenses possible on SLRs for the first time. The drawback is that the extra lens elements introduce more optical complexity and expense.

Mirrorless cameras One of the big advantages of mirrorless cameras is that the back of the lens assembly can be physically much closer to the focal plane (the film or image sensor). This means that wide-angle lenses can be built with shorter back focal distances, reducing the expense and, in theory, improving quality.

Varifocal and parfocal Most zoom lenses don’t quite meet the traditional technical definition. True zoom lenses, or parfocals, maintain correct focus when you adjust the focal length. However, varifocals lose focus, forcing you to refocus each time you change the focal length. The vast majority of consumer zoom lenses these days are actually varifocals. Only expensive pro lenses tend to be parfocals. However, because most photographers just autofocus all the time anyway, it’s not something that many people even notice. And so everybody calls both types zooms without realizing there’s a difference.

B

A

▲ This is an optical block diagram of a Nikon 20mm lens. Note how the rear principal point (A) is a kind of virtual point, floating in space out the back of the lens itself.

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Are those numbers for real?

Converging lenses

Biconvex

Planoconvex

Positive meniscus

Planoconcave

8.3 Lens element types When most people think of lenses, they think of magnifying glass lenses: round discs of glass, curved outward on each side. This type of lens is shaped like an edible lentil, which is actually the origin of the word: the lentil plant is Lens culinaris in Latin. In fact, only one specific type of lens is lentil shaped—the biconvex lens. Lenses come in a variety of shapes, but they are either converging or diverging. Converging (or positive) lenses direct light inward to a central point. Diverging (or negative) lenses, on the other hand, direct light outward. These two types can also be subcategorized depending on physical shape, as shown here in cross section.

Diverging lenses

Biconcave

One of the dirty secrets of the camera industry is that there tends to be a lot of rounding up going on. Most zoom lenses don’t have quite the focal length range they advertise. It’s not uncommon for, say, a 24–70mm lens to actually have a 25 to 71mm range when properly measured. The focal range can also vary a lot as the focus changes. The advertised focal lengths are supposedly accurate(ish) at infinity focus, but they often shift a lot when the lens is close focused on something. A 70–200 lens might suddenly become only 150mm at the long end when focused nearby. Generally this field of view shift is merely annoying with still photography, though it can be a problem with video (see focus breathing, section 8.25).

Negative meniscus

▲ The three basic converging lenses are the biconvex, the plano-convex (i.e., flat on one side), and the positive meniscus. All are thicker in the middle than at the edges. The three basic diverging lenses are the biconcave, the plano-concave, and the negative meniscus. All are thinner

Converging lenses focus light inwards

Diverging lenses spread light outwards

in the middle than at the edges.

Lens elements of all types are used to build modern camera lenses. Incidentally, negative meniscus lenses are used for correcting near-sighted (myopic) human vision. And positive meniscus lenses are used for farsightedness (hyperopia). Meniscus lenses make much thinner spectacle

lenses than convex or concave lenses would. And for bonus trivia points, there’s a technical error in William Golding’s 1954 novel Lord of the Flies: you can’t start a fire using a myopic person’s glasses, since negative lenses don’t focus light to a point.

8.4 Optical properties Although lens elements may all look similar, they’re actually made from different types of glass, plastic, or crystal. Each material is chosen for its unique optical properties, allowing lens designers to achieve specific goals.

Optical glass Glass, a hard transparent material usually made from ordinary sand (silica, or SiO2) and other materials, is the basic ingredient in the majority of quality camera lenses made today. Lenses are made from an extremely pure form of optical glass that has been refined to the point of incredible transparency. Regular window glass, used in windows, coffee tables, and the like, is considerably less pure. Try looking at the edge of an ordinary flat glass object. You’ll see a distinct greenish tint, caused by trace amounts of iron oxide.  These large glass panels at Cologne Bonn Airport in Cologne, Germany, all have a distinct pale green tinge.

This isn’t to say that optical glass is all the same. There are thousands of different formulations produced globally by a handful of specialized glass companies. Each type bends light to differing degrees—different refractive indexes—and so lens designers choose their formulas very carefully.

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Types of glass The optical advantages of combining lens elements made from different flavors of glass have been known for years. For example, telescope lenses since the 1700s have included both flint glass elements (high refractive index, traditionally containing lead oxide) and crown glass elements (low refractive index, containing potassium oxide). Pairing a crown glass element and a flint glass element dramatically reduces a kind of blurring known as chromatic aberration (see section 8.8). Different optical flaws can be corrected by using various combinations of glass. Other exotic materials for altering the refractive index of glass include boric oxide (borosilicate lenses), zinc oxide, barium, arsenic, lanthanum, and thorium. BITTEN BY A RADIOACTIVE LENS Since the 1990s, lens makers have been under increasing pressure to phase out ▲ Lead crystal (which is technically glass containing lead, and not crystal at all) used in expensive glassware has a characteristic sparkle to it because of its high refractive index.

the use of toxic materials in lens glass. Therefore, modern “eco” lenses are free of harmful materials like lead, arsenic, cadmium, and thorium. But there are a lot of old lenses sitting on shelves out there. And amazingly, a few are even radioactive, such as the thorium lenses made from the 1940s through the 1970s! Fortunately, thoriated lenses aren’t hugely dangerous if used only occasionally, but you wouldn’t want to store one in your pocket. Or grind it into sand and inhale the dust.

 The lens on this classic Pentax Spotmatic camera, a Super Takumar 50mm 1.4 from the late 1960s, has noticeably yellowish-brown glass. This discoloration is actually caused by a radioactive lens element containing thorium.

Other materials Glass has been the lens maker’s material of choice for centuries. It’s sturdy, well understood, scratch-resistant, affordable, has excellent optical properties, has easily modified refractive abilities, and so on. However, it’s not the only material used. Eyeglasses are commonly made from plastic polymers, as are many lowcost lenses for toy cameras and phone cameras. Quality camera lenses do not include plastic elements except for some aspherical lenses (see section 8.10). Plastic scratches easily, historically had no high refractive index formulations, isn’t great for thick lenses, and hasn’t been able to shake off its low-quality reputation (hence euphemistic marketing terms such as “polymer lens,” “optical resin,” and my favorite, “UV-hardened optical-grade resin film.”) Some lenses also include crystal material such as fluorite (see section 8.8).

8.5 Manufacturing Making pure glass is just the first step in the complex process of lens manufacture. The molten glass is made into flat discs known as blanks. These blanks are then cut, shaped, and ground into the precise curved shapes required. The lens elements are polished to a perfect transparency and treated with special antireflective coatings. Finally, the lenses are assembled by highly trained technicians and mounted by hand inside the lens barrel assembly.  Specialized tools such as this adjustable lens wrench are used for assembling and repairing photographic lenses.

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These basic techniques aren’t new. Computer technology has made complex designs possible, new exotic glass additives have been invented, and advanced coatings have been created, but the fundamental process of lens manufacture follows the process established by optical pioneers a century ago.

8.6 Seeking the perfect lens Like ancient Greek philosophers and their ideal philosophical chairs, lens designers dream of the perfect theoretical lens. Such a paragon of lenses would be completely sharp at all settings. Perfect contrast. Perfect color. Straight lines would record as straight. But real life isn’t like that. Real life is complicated, messy, random. Real life is about the cost of materials and manufacturing. It’s about the engineering tolerances of machines and the accuracy of human workers. In short, it’s about compromises. Lens design is particularly full of compromises. Consider the typical camera lens, with its multiple lens elements. Why so many different pieces of glass? Well, one element might correct a specific type of optical problem. A second element might fix a second type of problem. But together these two elements might cause a third type of problem, so another element is needed to counteract it. And so on. So, theories of unattainable ideal forms aside, there’s no such thing as a perfect lens. Each lens is either good or bad for certain tasks, depending on what your priorities are and how much money you want to spend. Sometimes the compromises you make when shopping are obvious. A truck designed to haul heavy cargo is probably a bad choice of vehicle for a drag race. A pair of elegant patent leather shoes is probably a bad choice of footwear for a mountain hike. Lenses are no different, and each lens design is a compromise—usually between price and performance. Novice photographers are often shocked that the new lens they just bought lacks the extreme wide-angle coverage they were expecting. Or that it yields blurry results when photographing distant birds. This kind of thing is disappointing, but photography can be an expensive endeavor.

8.7 Optical flaws All lenses suffer, to one degree or another, from common optical flaws. Many flaws are known as aberrations because they represent deviations from a theoretical ideal lens.

Because this book isn’t an advanced text on optics, I won’t describe all of the various types of aberrations, just common ones that directly affect image quality in contemporary lenses.

8.8 Chromatic aberration: color fringing One very noticeable optical problem is colored fringing at the edges of highcontrast areas. This can have different causes, but chromatic (i.e., color) aberration is often to blame. And the fundamental cause of that is an optical principle known as dispersion. A familiar example of dispersion is the rainbow. As Isaac Newton demonstrated in the 1660s, what we see as white light is actually made up of different colors across the spectrum. A raindrop or glass prism can break up white light, revealing all its constituent colors. Dispersion happens because the amount of refraction, or bending of the light, depends on the wavelength or color. Blue light, for example, bends more than red.

▲ Following in Newton’s footsteps: a prism shows the colors that make up white light. Notice how this real prism produces much messier results than the idealized prism on Pink Floyd album covers and the like. It’s not just “white light in; rainbow out.” There are other rays of light leaving the prism, caused by reflections off the surface of the uncoated prism’s glass. And, while we’re busting myths, it’s also completely untrue that you can take a second identical prism and bend the rainbow back into white light. You can focus the rainbow down to a white point using a converging lens, however.

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 A beautiful double rainbow, such as this one in Zaragoza, Spain, is a classic example of optical dispersion in nature. Light refracts and disperses as it enters each raindrop, is reflected internally, and is then refracted and dispersed a second time. The secondary rainbow is dimmer and has a reversed color order because the light has reflected off the inside of the raindrops.

While rainbows of colors are very pretty, they’re also problematic for lenses. The same laws of physics also cause unwanted color fringing. Take the large uncorrected glass lens shown below. Note how areas of high contrast are broken up into colored stripes in a pretty extreme example of chromatic aberration.

There are actually two types of chromatic aberration: axial (or longitudinal) chromatic aberration and transverse chromatic aberration (TCA). Of the two, TCA is probably the most common; it causes color fringing that gets more pronounced toward the edge of the picture. TCA can’t be corrected for by adjusting anything, but axial chromatic aberration can be reduced by stopping down the lens.

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 This photo has heavy color fringes around high-contrast areas. It’s pretty common to see blue or red fringes around light sources like this. Other common cases that reveal color fringing include tree branches against a sky and the edges of windows (when shot from inside looking out). This is Arts et Métiers metro station, redesigned in steampunk style in 1994 by Belgian comic book artist François Schuiten. Paris, France.

Low-dispersion glass A key reason that lens makers put additives into glass, or employ glass containing no silica, is to create low-dispersion lens elements. Low-dispersion glass is less likely to cause fringing. Lenses with minimal chromatic aberration are sometimes known as apochromatic or APO lenses (older, less-efficient types are known as achromats). To emphasize the point, manufacturers often market their glass under all kinds of exciting names, including low-dispersion (LD), extra low-dispersion (ED), super ED, ultra low-dispersion (UD), super UD, special low-dispersion (SLD), and so on. Knowing that a given lens contains an exotic form of low-dispersion glass isn’t useful for comparing lenses across manufacturers, simply because there’s no universal standard as to what constitutes super ultra gonzo LD glass or whatever. However, it can be useful for examining lenses within a given manufacturer’s lineup. For example, Nikon’s best telephotos contain ED or super ED glass and are marketed accordingly. Canon’s L series lenses often contain UD or super UD glass.

Fluorite Lenses can be made from materials other than glass. Canon is well known for employing synthetic calcium fluoride (CaF2), or fluorite crystals, in many high-end telephoto lenses. Fluorite is a very effective low-dispersion material.

▲ A traditional approach to reducing axial chromatic aberration is to pair up two lens elements, each made from different materials, to counteract the dispersive effect. A pair of lens elements is known as a doublet.

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Fluorite does have drawbacks, though. It’s expensive to produce, expands in size at higher temperatures, and is quite soft and scratches easily. Canon lens barrels containing fluorite elements are typically painted a near-white color (see section 3.22) so they don’t heat up as much in sunshine, and fluorite elements are used only inside the lens. The exposed front and rear elements are always made of glass.

Digital correction

▲ Fluorite is a naturally occurring mineral, sometimes called fluorspar. Natural fluorite such as this is too impure to serve as lens material, so synthetic crystals have to be grown in the lab.

 Adobe Photoshop software being used to compensate for color fringing caused by lateral chromatic aberration.

Since TCA is fairly predictable for each lens, and it occurs for specific color ranges, it’s not that difficult to correct for the problem inside a computer. You get a slight loss of sharpness, but most people consider that a reasonable sacrifice. Many image processing programs such as Adobe Photoshop have chromatic aberration compensation functions built in. And some cameras can even apply TCA compensation automatically onto all the files they produce, cleverly hiding the problem in the first place.

8.9 Spherical aberration Spherical aberration is an optical problem that’s unaffected by color—and one of the oldest known aberrations. Most optical lenses can be thought of as a segment cut from a larger sphere. Imagine taking a clear glass ball and slicing off a precise wedge. (That isn’t how lenses are actually made; this is just an illustration.) Since our hypothetical lens is cut from a perfect sphere, it has a constant radius of curvature across the surface from one edge to the other. This sounds good, but spherical lenses aren’t actually that great at projecting sharp images in a photographic context.

Uncorrected spherical lens cannot focus all rays at the same image plane

Aspherical lens can focus all rays at the same plane

As this diagram shows, when the image-recording surface is flat (as film or digital sensors are), it isn’t possible for a spherical lens to focus incoming rays accurately across the whole surface. Spherical aberration has been a basic challenge throughout the history of lenses and is one of the earliest recognized aberrations: al-Haytham even wrote about it a thousand years ago. Early Victorian portrait lenses tended to have a lot of spherical aberration, yielding a characteristic softness to the photos. The traditional way of minimizing spherical aberration is to use certain combinations of lens elements, particularly doublets. Another method is to employ aspheric elements.

▼ This lens, probably from a projector, is much thicker than the typical elements found inside a camera lens, but it clearly demonstrates how the curvature of a normal lens is a segment of a sphere.

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8.10

Aspheric lens elements

Lens elements that aren’t spheres in cross-section are known as aspheric lens elements, and they tend to be more expensive to manufacture than regular lenses. They can be a great way of suppressing spherical aberration. Some manufacturers like to tout their use of aspheric elements as though they’ve discovered some amazing new form of technology. In fact, people have been making aspheric lenses since the 1600s. It’s just been in the past few decades that precise and affordable manufacturing technologies have been developed. In short, the term ASPH appearing in a lens name is nice, but there are plenty of great lenses out there without aspherical elements.

▲ This lens is aspherical, and so the curve of its surface does not match that of any part of a sphere.

There are several different ways to manufacture an aspheric lens element.

Ground aspheric By far the most difficult way is to use a special grinding machine. This can produce incredibly precise and very expensive lens elements. The best wide-angle lenses from top makers tend to employ ground aspheric lenses. For example, one of the criteria for a Canon L series lens can be the presence of a ground aspheric lens.

Molded aspheric ▲ Two of the eight elements in this 18mm lens are molded aspherical elements, and Fujifilm wants everybody to know!

A far less-costly method is to use a special mold, ideal for mass production. A lot of glass aspheric SLR lenses, sometimes called GMo lenses, are made this way. Cheap plastic aspheric lenses, for less-demanding applications like phone cameras, are also molded.

Hybrid or replicated aspheric The hybrid method takes a regular spherical glass lens and glues a transparent plastic aspheric layer over the top. This lowers the overall cost, but the majority of the lens material is still high-quality optical glass. Only the aspheric cap is plastic, or “optical resin.”

8.11

Intentional spherical aberration

Lens makers normally take great pains to eliminate spherical aberration, but there are some lenses that actually induce it on purpose.  Soft focus was popular with boudoirtype photography in the 1970s and 1980s. Whether this is delightfully romantic or unspeakably cheesy is up to you.

As noted earlier, Victorian portrait lenses often resulted in photographs that had a soft dreaminess caused by spherical aberration. They weren’t simply out of focus. The 1866 Dallmeyer Patent Portrait lens was the first of many nineteenth century dreamy bestsellers, turning a technical weakness into a marketing advantage. Because some people like the look, there are a few modern lenses that can deliberately induce a degree of spherical aberration for artistic effect. Such lenses are popular with some older portrait sitters because soft focus can slightly reduce the appearance of skin wrinkles, though at the cost of increased flare, decreased contrast, and glowing halos (i.e., halation) around bright areas of an image. The Canon EF 135mm 2.8 SF is a sharp portrait lens that goes soft at the turn of a ring, and the Pentax SMC 85mm 2.8 FA Soft lens has softness levels related to aperture settings.

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▼  The Canon soft focus lens has a normal or sharp position (0) and two levels of softness (1 and 2).

0

1

8.12

2

Distortion

Lenses are curved optical surfaces that have to project light onto flat imaging surfaces. And sometimes photos of objects with rigorously straight lines can get a bit bent out of shape. Take this picture of a railroad track in White Rock, Canada.

Notice how the top rail runs straight across the middle of the frame. But the lower or nearer rail appears to be bulging downward out of the frame. The same thing is apparent with the horizon, which seems to be bulging up.

In real life, of course, the two rails were perfectly parallel. This curving effect is due to an inherent optical flaw with the lens known as geometric distortion—in this case barrel distortion. Most lenses, with the exception of fisheyes, are rectilinear. This means that a straight line appearing anywhere in the frame should record as dead straight. But this can actually be tricky to achieve, and many lenses distort the image the farther you get from the center. On the list of lens makers’ compromise priorities, distortion tends to be less important than things like sharpness and contrast because most people don’t photograph rectangular objects very often and therefore don’t notice the problem.

▲ First, here’s an improbably perfect rectilinear view of a

▲ Barrel distortion is pretty common, especially with wide-

Venetian palazzo.

angle lenses. As the name implies, it results in a bulging outward effect.

▲ Pincushion distortion is a bit less common and is more

▲ Complex (or mustache) distortion is a combination of

likely to afflict telephoto lenses. It seems to sag inward.

both barrel and pincushion in that the distortion bends in or out, depending on the distance from the center.

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The three basic types of distortion (barrel, pincushion, and complex/ mustache) are shown using simulated shots on the previous page. Generally, distortion is more of a problem with zooms than with primes. This is partly because zooms are more complex to make, but also because primes are more likely to be marketed to professional photographers. True macro lenses, which are often used to photograph stamps and other rectangular objects, are frequently low-distortion by design. Fortunately, distortion is another problem that can be fixed pretty easily inside a computer. Most image-editing programs can correct for barrel or pincushion distortion, though fixing complex distortion is problematic. Some digital cameras also correct lens distortion in-camera with each picture taken.

8.13

Other aberrations

In 1857, German mathematician Ludwig von Seidel (1821–96) published a paper describing five common forms of aberration. These are now often named after him, though it should be noted that he didn’t discover them. Two we’ve already met: spherical aberration and distortion. The other three are coma, astigmatism, and curvature of field.

Coma Coma is fortunately rarely seen, except in very cheap lenses. It’s a change in magnification across an image that results in bright point sources appearing as stretched objects, like a comet’s tail. The effect worsens the farther you go from the center of the frame.

Astigmatism

▲ This photo of the night sky should record a black field with perfect points of light. However, the lens used has severe coma, which caused the coneshaped aberrations seen here. This is a closeup view of one edge of the frame.

Astigmatism in camera lenses is a focus problem that gets worse the farther you get from the center of the image. It’s a blurring that affects lines that form the spokes of an imaginary wheel or lines that circle the rim, but never both. As a result, points that are away from the center tend to be blurred in one axis or the other, but not both. It’s kind of a tricky flaw to spot because it can just look like general blurring caused by other factors. Astigmatism is only really recognizable as such when test patterns and the like are photographed. Note that it differs from astigmatism in the human eye, which is caused by uneven curvature of the cornea or lens.

C B A

▲  This simple test chart (left) demonstrates the effects of astigmatism. Examine the crop of an actual photo (right) taken of the chart using a low quality lens. You’ll notice that the cross marked A, which was at the very center of the lens, is basically sharp. But as you move further from the center of the lens you start getting focus problems. However, it’s not a simple matter of the focus worsening the further you get from the middle. Look at point B. The line radiating out from the center is known as a sagittal or radial line, and it’s reasonably sharp. But lines perpendicular to it, known as meridional or tangential lines, are blurrier, as can be seen at point C. To use our spoked wheel metaphor, the sagittal/ radial lines are the spokes and meridional/tangential lines are the rim.

Curvature of field This aberration, also known as Petzval field curvature, flat field reproduction, and flatness of field, is most apparent when you’re photographing a flat object. The object, instead of imaging correctly onto the flat surface of the film or image sensor, projects an image that would be sharp only on a curved surface.  A collection of Japanese name stamps, or “hanko,” pre-engraved with common surnames. These stamps are traditionally used for signing documents, receiving parcels, and so on. As this type is of the informal variety they are also known as sanmonban. A hanko shop, Tokyo, Japan. The lens used is poorly corrected for curvature of field, and so while the hanko at the middle of the frame are completely sharp, the ones out to the edge are quite blurry. There’s quite a bit of barrel distortion as well (see section 5.3).

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Macro lenses are typically well corrected for this aberration because they’re often used to photograph flat items. However, it’s difficult to correct for astigmatism without introducing curvature of field.

8.14

Sharpness

You may have noticed that my discussion of lens quality hasn’t really touched on sharpness. This is because the sharpness of a lens—its ability to accurately resolve and reproduce an image—is determined by many factors. Different types of aberrations can decrease optical sharpness in different ways. A lens may seem pretty sharp on a subframe DSLR, but might look terrible on a full-frame camera where the blurry corners are more apparent. Another lens may look fine when used stopped down to f/8, but has a distracting glow around bright objects when used wide open. Or a lens might seem quite satisfactory when producing 4×5 prints for the kitchen fridge, yet seem dreadful to a professional producing huge poster-sized images. In short, it’s much more complex than “this lens is sharp” or “this lens isn’t.” Having said that, there are many test procedures for measuring the sharpness of a lens. These tests determine resolution, or the ability of a lens to distinguish between increasingly thin black and white pairs of lines (counterintuitively, two black lines don’t constitute a pair—a black line and a white line do), and acutance, or the sharpness of the transition between high-contrast lines—something improved by digital “sharpening” programs. For more details, have a look at my writeup of MTF (see section 8.35).

8.15

▲ The sun may be out of frame, but it still results in a lot of flare.

Lens flare

Everyone has seen it. Lens flare. Those mysterious blobs of light that sometimes appear in photos. But what is flare, and what causes it? Under ideal circumstances, light simply enters the front of the lens, passes through the various lens elements, and hits the surface of the image sensor or film, recording an image. But things don’t always work that way. Sometimes light ricochets around inside the lens before being recorded. And sometimes light hits the lens surface at an oblique angle and is reflected. The result is lens flare, and it can manifest itself as a kind of washed-out haze. In extreme situations, particularly when bright light sources are involved, it can cause bright blobs or streaks of light. In short, flare is an optical phenomenon, and usually with the same basic cause as any reflections off a glass surface.

▲ The low-contrast look of a single-coated lens from the

▲ This shot was created completely in-camera, and no re-

early 1960s pointing towards the sun. Older lenses are often

touching was performed. A bright lamp was positioned just

not very resistant to lens flare.

outside the camera frame, and a plastic lens with no coatings was used. The shot was composed using Live View to ensure the model’s hand lined up correctly with the lens flare.

Unfortunately for some online theorists, lens flare blobs are demonstrably not spiritual orbs captured through the magic of photography. It’s pretty easy to make the magic “orbs” come and go at will by adjusting bright light sources relative to the lens (or avoid on-camera flash, which illuminates airborne dust, another cause of the “orbs.”)

Reducing flare Fortunately, flare is usually easy to minimize if the cause is a light source located outside of the frame. You can usually block such non-image-forming light with a simple lens hood (see section 6.2). Failing that, holding a black card or your hand or a movable panel—or anything handy—can reduce flare. Such barriers are known in cinematography as “flags.”  This circular fisheye lens has pretty awful flare caused by light bouncing off internal components and glass surfaces. It’s not too bad in daytime shots, but in high-contrast night shots it can be a real problem. This shot, of the Piazza del Duomo in the walled medieval town of San Gimignano, Italy, is fairly unusable. 8mm fisheye, full-frame camera. f/5.6, 4 sec. ISO 100.

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It’s more of a problem when the flare-inducing light source is visible within the frame, such as car headlights or the sun. Then flare may be unavoidable, and the amount depends on the design, construction, and condition of the lens. These are some things that can cause lens flare: f Flare is usually caused by light reflecting off glass surfaces. So, for ex-

f f f f

ample, a prime lens with 6 pieces of glass will normally flare less than a 22-element zoom lens, all things being equal. A cheap or older lens with poor or no optical coatings will flare badly, often in the form of lower contrast. A lens with dirty glass or filters will be similarly affected. A poorly designed lens with reflective internal components (unpainted metal pieces, for example) can suffer from flare. Fisheye and extreme wide-angle photos frequently show flare outdoors, simply because it’s difficult to keep the sun off a lens that covers large swaths of a scene.

A flare for fashion Flare isn’t always a mistake. For instance, lowered contrast and flare can help lend a gauzy, hazy romantic summer’s afternoon feeling to an image, albeit in a clichéd 1960s–70s sort of way. In fact, this period marked the beginning of intentional flare in movies. Cool Hand Luke (1967) was controversial for many reasons, including cinematographer Conrad Hall’s iconoclastic use of flare to convey gritty realism. Filmmaker Steven Spielberg’s Close Encounters of the Third Kind (1977) is marked by heavy direct lens flare from in-frame light sources.  A traditional red phone booth in front of the Victoria and Albert Museum, London, England. I placed a Quantum Qflash flash unit, controlled by a FreeXwire radio remote, inside the box to get the burst of direct light, which has led to some flare in the final shot. Note the green blob to the left and the arcs of light. 28mm full frame. f/5, 0.4 sec. ISO 200.

Other filmmakers go to extreme lengths, sometimes even painting in fake computer graphic flare, to give a dynamic, vérité sense to their films. J. J. Abrams, the director of Star Trek (2009), actually had assistants all over the set shining bright lights right onto the lenses to deliberately induce excitingly dramatic bursts of flare. The anamorphic lenses traditionally used by big-budget movies cause a particularly famous horizontal line lens flare from bright light sources (see section 9.11).  This photo was taken using a digital camera, modified to record infrared by removing the sensor’s IR-absorbing filter. One side effect is that the sensor’s antireflective coatings were also lost, and so the camera suffers from huge amounts of flare with bright light sources, though the result can sometimes be kind of cool. The Temple of Flux by Rebecca Anders, Jess Hobbs, and PK Kimelman, at the Burning Man arts festival 2010. The Black Rock Desert, Nevada, USA. 24mm, 1.6x subframe. f/9.6, 1/200 sec. ISO 100.

8.16

Antireflective lens coatings

A quick glance at a shop window reveals that light can do one of two things when it hits a piece of glass: it can pass straight through, as one expects from transparent material. But from certain angles it can also be reflected as though the glass were a mirror. So all glass can be either transparent or reflective, or both. The problem is that we don’t want camera lenses to be reflective. In the early days of photography, reflections were a serious technical problem. Lenses had to be limited to just a few lens elements. Too many

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elements and you had so much light bouncing back and forth internally that the lens became unusable. Old lenses were also fairly low contrast because of these reflections. As early as 1904, British lens maker H. Dennis Taylor (1862–1943) had patented a process for deliberately tarnishing a lens with acid to reduce reflectivity, but his method was not consistently effective and remained a curiosity. Finally, Ukrainian researcher Olexander Smakula (1900–1983), working at German lens maker Carl Zeiss, devised a reliable process in the 1930s. The company’s fine vacuum-deposited lens coatings cut reflections dramatically. Lens coatings are thin films of materials, such as magnesium fluoride, which cause interference at certain wavelengths of light. This interference reduces the amount of light reflected back without significantly altering the amount of light passing straight through.  This is a demonstration lens made by Zeiss. The circular patch at the center is coated, while the rest of the glass is not. The effectiveness of the coating at reducing reflections is obvious. From the collection of the Zeiss Optical Museum, Oberkochen, Germany.

The technology was a real breakthrough, and modern zoom lenses finally became possible, though it remained a German military secret for some years. American researcher Katherine Blodgett (1898–1979), working for General Electric, also invented a process in 1938 involving very thin coatings, but it was too fragile for commercial use.

8.17

Multicoatings

Over the years manufacturers have honed the coating process, developing multiple layers of coatings that cut down an extraordinary amount of unwanted reflection.

For example, a lens might have six elements with two pairs cemented together, resulting in eight glass surfaces exposed to the air. If all surfaces are uncoated, an incredible one-third of the light passing through can be lost to flare. Coatings reduce that amount to maybe 5 percent. It’s easy to see how a complex 20-element lens would be impossible to make without coatings. It’s simple to tell a coated lens, filter, or pair of eyeglasses from an uncoated one. Look carefully at the reflection of a bright white light source such as a lamp. If the reflection is muted, or tinted green, red, purple, or some other color, then the glass surface is coated with antireflective material. If it reflects white like a mirror, it’s uncoated.

 An uncoated (plain glass) polarizing filter and its multicoated equivalent.

Light reflected by coated glass does so at certain wavelengths, which is why coated elements appear to reflect certain colors. However, the coatings themselves are transparent and don’t tint the final photo in any significant way. The color of a lens coating doesn’t guarantee anything about how well it works.  Image sensors have coatings as well. This camera’s sensor coatings happen to reflect pink light: it isn’t a “kawaii” Hello Kitty camera, which tints everything pink or anything.

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Multicoatings are standard on camera lenses today and are marketed under various company-specific names. Makers also continue to refine the technology to improve lens performance.  The multicolored reflections of a modern multicoated camera lens, showing how each element in this particular lens has different coating properties.

For example, Nikon’s Nano Crystal Coat and Canon’s Subwavelength Structure Coating (SWC) are the latest coating technologies, based on the creation of submicroscopic coating structures on the surface of the glass. They’re too fragile and expensive to be used on all but a few surfaces of current lenses, however.

Drawbacks of coatings Coatings work very well, but they tend to smudge when dirty, creating bright colored blobs on the glass surface. This is a common problem on coated eyeglass lenses as well. The blobs don’t add a color cast but do lower the quality of the image. Coatings can also be quite fragile and easily scratched. For these reasons it’s critical to keep multicoated lenses scrupulously clean and free of grit (see section 8.17). When shopping, consider lenses and filters with scratch-resistant coatings. ▲ Finger grease smudges badly on coated glass.

“Digital” lens coatings The introduction of digital cameras brought some changes to the design of lens coatings. Because digital sensors are flat and highly reflective, it was found that the rear elements on many lenses benefited from revised

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coatings. These give improved performance with digital cameras. This fact, while true, tends to be a bit overstated by camera makers. An old lens designed for film cameras typically works just fine on a compatible digital camera.

8.18

Bokeh

Boke, boké, or bokeh is an interesting property of a lens, particularly because it’s so important to some people but completely irrelevant to others. In fact, many people don’t know what it is and have never considered it. Basically the term refers to the appearance of out-of-focus areas of an image. It may sound odd to care about blurry portions of a photo, but it can actually matter quite a bit when dealing with shallow depth of field, especially with portraits. Portraits generally look much classier when distracting backgrounds are smoothed over. Consider this photograph. The foreground leaves look sharply defined as one would expect. But the background leaves, instead of being smoothly out of focus, have a strange jagged look. This is considered to be very noisy and displeasing bokeh.

▲ Good bokeh is soft and smooth.

▲ Poor bokeh is evidenced by this noisy and disruptive background blur.

Bokeh is an innate and subjective property of a given lens design. Its quality is determined by countless factors, including the shape of the aperture diaphragm (round shapes help, though this factor is usually overstated), the lens formula, the focal length (longer is usually better), the maximum aperture (larger usually means smoother), and so on. It can’t be improved after the fact, though it can be worsened by putting obstructions on the front of the lens.

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Some lenses are designed with good bokeh in mind, primarily for portraiture. The Sony/Minolta STF lenses and the Nikon DC lenses are two examples. The STF (smooth transitional focus) lenses contain a special “apodization” lens element that serves as a kind of graduated neutral density filter. This element improves bokeh by smoothing the edges of background elements. The Nikon DC lenses have adjustable “defocus control,” which essentially introduces spherical aberration. This softens the entire image, including background bokeh. Other lenses can have unusual forms of bokeh. For example, lenses of a Biotar design, or copies thereof, will sometimes demonstrate an effect that people have taken to calling “swirly” bokeh. This is an apparent rotational effect to background areas that are out of focus. Whether this is a good thing or not is quite subjective.  Swirly bokeh, as seen by a 58mm f/2 Russian-made Helios lens. This lens is modeled after the Zeiss Biotar design and has heavy swirl.

▲ The characteristic ring-shaped bokeh of a mirror lens.

Finally, mirror (catadioptric: see section 8.26) lenses are notorious for a very intrusive form of bokeh. Because mirror lenses have a light-blocking central disc, bright highlights appear as a doughnut shape in the photo. This also leads to tree branches, grass, and so on looking very noisy and double-line in nature. The word bokeh, incidentally, is a Japanese loan word with various contextual meanings, often implying mental fuzziness or stupidity. It’s usually written in English as bokeh or with an acute accent (boké) to emphasize the fact that it’s pronounced as two syllables. The o in bo is similar to the o in bone and the ke is pronounced like the ke in kestrel.

8.19

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Vignetting

Vignetting is the common name for a darkening around the edges of a picture. Vignetting has a number of potential causes, and sometimes the distinction is made between mechanical vignetting (caused by physical obstructions to light) and peripheral darkening (caused by falloff of light or some other optical effect). In Victorian times many popular lenses of the day just weren’t able to illuminate the edges of a picture, properly owing to their simple optical design. While arguably caused by an optical defect, the vignetting look actually became a popular aesthetic since dark edges help draw the viewer’s eye toward the centre of the frame, albeit in a somewhat somber fashion. Today vignetting effects are sometimes applied digitally, this time to lend a retro look to photos. However, there are some technical reasons why images can show the effect. Dark edges can be caused by something simply getting in the way. A wrongly sized filter, hood, or filter adapter can block light around the edges, resulting in mechanical vignetting (see section 6.2). Peripheral darkening can also be very apparent with certain lenses. The farther you get from the optical center, the more light has to bend, especially with wide-angle lenses for rangefinders. This effect is known mathematically as cos4 vignetting.

▲ Flowers adorn the side of a whitewashed house on the island

▲ This is the same shot digitally altered to brighten the corners

of Mykonos, Greece. This shot has heavy corner darkening (or

and eliminate the vignetting.

vignetting).

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Film responds fairly well to off-axis light. But digital chips have sensors placed within tiny little wells or shallow depressions. Accordingly, if light enters at an angle, it may mostly strike the edges of the well and not properly illuminate the sensor transistor at the bottom. For this reason digital cameras are often more susceptible to this sort of peripheral darkening than film cameras. Fortunately this is a fairly straightforward effect to compensate for digitally. In fact, many digital cameras can read the optical characteristics of a lens electronically (or use a special barcode in the case of some Leica cameras) and compensate internally for this sort of darkening. Other cameras have special “microlenses” positioned over each sensor to compensate for the problem optically.

8.20

Close focus distance

Little children can see things placed unbelievably close to their faces. But, as we age, our ability to focus closely diminishes. By the time we reach our 50s and 60s, most of us are holding books at arm’s length or peering through bifocals. Camera lenses differ similarly in their ability to focus on nearby objects, though of course this is an inherent property of the lens rather than the consequence of biological aging. Macro lenses can focus quite closely on objects by definition—they wouldn’t be very good closeup lenses otherwise. But most non-macro lenses have limited close-focus capabilities. Extension tubes, which just move the lens farther away from the lens or sensor, can improve the closefocus abilities of any lens (see section 6.5).

8.21

The hyperfocal distance

With most photography you simply focus on whatever you want to be sharp. Portraiture or interior work is done this way. But with landscapes, the goal is often to get as much of the scene in focus as possible, from a nearby subject all the way to the horizon (which is known as “infinity” in photographic terms, even though of course it’s very much a finite distance). The hyperfocal distance is the nearest point to which a lens can be focused while ensuring that objects out to infinity are also in acceptable focus. At the hyperfocal distance, you’ve also got the greatest depth of field. The near limit is the distance closest to the camera that provides an acceptably sharp focus, and the far limit is the distance that is farthest.

 By focusing at the hyperfocal distance, everything from the nearby clump of grass to the distant Sierra Nevada mountain range is in focus. The Alabama Hills (which are actually in California) at dawn, Inyo County, California, USA. 40mm full frame. f/11, 30 sec. ISO 100.

The hyperfocal distance is a fairly simple concept, with a somewhat complicated mathematical basis. The definition also relies on a key point of subjectivity: what is acceptable focus? For this there is the notion of the circle of confusion.

Circle of confusion The circle of confusion (CoC) sounds like the leadership team for agents of chaos, but it’s actually the smallest circle size that the human eye can resolve as a circle or disc. Anything smaller and we can’t tell the difference between the circle and a point. This is a subjective value that depends on the size of the print and how good the person’s vision is. Various accepted values for the CoC are used by different manufacturers and typically assume an 8"x10" print is being examined at normal viewing distances. Canon, for example, uses a value of 0.035 mm as its CoC for full-frame 35mm cameras and 0.019 mm for its subframe cameras. Nikon seems to use 0.03 mm for full-frame and 0.02 mm for its subframes.

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Hyperfocal calculation With the CoC in hand, it’s possible to calculate the hyperfocal distance. If you feel like doing the math, here’s one formula for hyperfocal distance: H =

f2 Fc

▼ A wide-angle lens stopped down to f/13 ensures that everything in this French farmhouse kitchen is in focus. The low light and small aperture meant a tripod was a necessity. Cambieure, France. 20mm full frame.

H is the hyperfocal distance in mm, f 2 is the focal length squared, F is the f-stop, and c is the circle of confusion. Alternatively, you can refer to a depth of field calculator program (available on smartphones, etc.) or a precalculated chart.

f/13, 3.0 sec. ISO 100.

Using the hyperfocal distance Once you’ve got the distance, you focus to that point. The image in the viewfinder may look blurry, but remember that’s because your camera is metering wide open. To view the effect, you can press the depth of field preview button (see section 2.20) or engage Live View mode, if your camera has it. Another useful tool, when using prime lenses, is the depth of field scale on the lens (see section 3.9). If you set the infinity symbol (∞) to the desired aperture mark on the DOF scale, you’ll be focused to the manufacturer’s theoretical hyperfocal distance.

f/1.4 feet

f/1.4 meter

f/2 feet

f/2 meter

f/2.8 feet

f/2.8 meter

f/4 feet

f/4 meter

f/5.6 feet

f/5.6 meter

14mm

18.4

5.6

12.8

3.9

9.2

2.8

6.4

2.0

4.6

20mm

37.5

11.4

26.2

8.0

18.7

5.7

13.1

4.0

9.4

1.4 2.9

24mm

54.0

16.5

37.8

11.5

27.0

8.2

18.9

5.8

13.5

4.1

28mm

73.5

22.4

51.4

15.7

36.7

11.2

25.7

7.8

18.4

5.6

35mm

114.8

35.0

80.4

24.5

57.4

17.5

40.2

12.3

28.7

8.8

50mm

234.4

71.4

164.0

50.0

117.2

35.7

82.0

25.0

58.6

17.9

70mm

459.3

140.0

321.5

98.0

229.7

70.0

160.8

49.0

114.8

35.0

80mm

667.4

203.4

474.1

144.5

338.6

103.2

237.0

72.3

169.3

51.6

105mm

1033.5

315.0

723.4

220.5

516.7

157.5

361.7

110.3

258.4

78.8

135mm

1708.4

520.7

1195.9

364.5

854.2

260.4

597.9

182.3

427.1

130.2

8.22

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The diffraction limit

As discussed earlier, many optical aberrations can be minimized by stopping down the lens. In other words, a lens usually isn’t at its best optical performance when wide open. So going to f/8 or thereabouts can make pictures much sharper. But if that’s the case, why not stop the lens down to its smallest aperture? The reason is known as diffraction, and it’s why lenses get a bit blurrier with small f-stops. Essentially, light bends slightly when passing through small openings, causing a certain softening or blurring. This is why most lenses have an optical “sweet spot”—an aperture setting that offers the best performance. For most lenses, this is roughly midway in the aperture range, or a few stops down from wide open. Values around f/8 to f/11 usually offer the best trade-offs between aberrations and diffraction, though it differs from lens to lens. Diffraction, incidentally, is also the cause of star patterns around point light sources when lenses are stopped down, as discussed in section 2.18.

8.23

Diffractive optic lenses

Most lenses are built around the optical property of refraction. But diffraction is another way to bend light, as described earlier. It’s been known for years that transparent materials with tiny and closely spaced grids can be used to alter the properties of light, and such diffraction gratings have often been used for industrial purposes and cheesy party favors. Ordinary CDs and DVDs also demonstrate rainbow patterns caused by diffraction. However, Canon has managed to develop photographic lenses that employ diffractive elements. These elements, used in conjunction with

f/8 feet

f/11 feet

f/11 meter

f/16 feet

f/16 meter

f/22 feet

f/22 meter

f/32 feet

3.2

f/8 meter 1.0

2.3

0.7

1.6

0.5

1.2

0.4

0.8

f/32 meter 0.3

6.6

2.0

4.8

1.5

3.3

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2.4

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20mm

9.4

2.9

6.9

2.1

4.7

1.4

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24mm

14mm

12.9

3.9

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4.7

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28mm

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4.5

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7.3

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35mm

41.0

12.5

29.8

9.1

20.5

6.3

14.9

4.6

10.3

3.1

50mm

80.4

24.5

58.4

17.8

40.2

12.3

29.2

8.9

20.1

6.1

70mm

118.5

36.1

86.2

26.3

59.3

18.1

43.1

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29.6

9.0

80mm

180.9

55.1

131.5

40.1

90.4

27.6

65.8

20.1

45.2

13.8

105mm

299.0

91.1

217.4

66.3

149.5

45.6

108.7

33.1

74.7

22.8

135mm

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conventional glass elements, counteract chromatic aberration quite effectively and don’t create rainbow effects. To date Canon has produced only a couple of lenses with diffractive optics (DO). While dramatically shorter in length than purely refractive lenses, the DO lenses do suffer from a bit more flare than traditional lenses. Canon DO lenses are marked by green rings.  This shot was taken with a clear diffraction filter placed over the lens; no digital effects were added. The filter causes rainbow-colored stars to appear around bright light sources. Fun, if a bit 1980s.

▼ Large format film cameras, such as the one shown here, are often capable of complex movements of the lens board relative to the film. The bellows

8.24

Tilt and shift

and rails offer tremendous freedom of movement. In this view the lens is considerably shifted to the left, and tilted very slightly.

Normally lenses attach right to the front of a camera. The lens and image sensor or film surface are completely and perfectly parallel. Accordingly, the light entering the camera strikes the imaging surface at 90 degrees. Lenses are also perfectly aligned to the very center of the imaging surface. Normally this is a very good thing. But interesting possibilities arise if you can alter this angle or position. Older film cameras often have cloth or leather accordion-like bellows joining the lens and body. These bellows are flexible and permit the lens to be positioned independently of the camera back while preserving the light-tight nature of the whole camera. These lens movements are usually called rising/falling and tilt on classic view cameras. Modern cameras rarely use bellows, but special lenses capable of such lens movements are

available for many lens mounts. These are tilt lenses, shift or perspective correction lenses, and combination tilt-shift lenses. So why permit lens movements at all? Let’s examine the two basic types.

Tilt Most cameras have a precise and nonadjustable connection between lens and body. This means that the area of a scene that’s in focus can be thought of as a flat imaginary sheet of glass in front of the camera. This flat plane is precisely perpendicular to the image plane where the film or sensor is located. But by altering the angle of the lens while keeping the body fixed, you’re essentially tilting this plane of focus. There are two basic ways this can be used.  The left-hand lens has an optical axis perpendicular to the imaging surface. This is normal. But the right-hand lens is tilted 8.5 degrees to the left—the limit of which this lens is capable.

First, a tilt lens (sometimes called a “slant” lens in cinematography) can be used for extending the depth of field. Consider a field of flowers with distant mountains. Normally it would be quite difficult to get everything in focus, even by stopping down the aperture. But by tilting the plane of focus, it is possible to get everything sharp. This use of tilt lenses is popular with architectural and product photographers. Second, tilt lenses can be used for the exact opposite purpose: they can be used to narrow down the depth of field in interesting ways. This can be used for razor-thin depth of field for portraits and studio work. It also can be used for a fun “model world” effect. When lenses are tilted in this way, they somehow lend a toylike look to a scene. Our brains interpret the narrow slice of focus as a tiny model rather than a real-life scene. This second effect can be simulated in Photoshop after the fact.

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 It looks like a miniature town from a western-themed model railroad, but it’s the real thing. The ghost town of Bodie as seen through a tilt lens. Bodie, California, USA. 80mm tilt lens, 8° tilt, full frame. f/2.8, 1/1000 sec. ISO 100.

 Yes, it’s a photo and not a finely detailed model of downtown Tokyo, Japan. 80mm tilt lens, 8° tilt, full frame. f/2.8, 1/640 sec. ISO 100.

Shift Most lenses cast image circles that are just big enough to fill the image area. There’s no point in going to the expense of engineering a lens that has an image circle that’s simply too large. But shift lenses do exactly that. And by having a large image circle, it becomes possible to shift the field of view within the circle. This has some interesting uses.

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 The left-hand lens is normal. But the right-hand lens is shifted 12mm over to the left.

Perspective correction As described in section 5.10, there can be a problem of converging verticals with architectural photography. This is simply caused by camera position and perspective, but it can be undesirable if a rectangular building looks like a trapezoid. One way to resolve the problem is to photograph the scene with a shift lens. Consider the images to the right. The first shot shows the whole scene that can be captured by a tilt lens. By ensuring that the camera is on a level horizontal plane, a huge expanse of the ground is visible. But since only a portion of the shift lens’s field of view is actually recorded by the camera, it’s possible to shift the view upward so that the vertical lines in the image remain parallel. Note that this isn’t true perspective correction; it’s more like perspective compensation. You aren’t taking a photo from the correct physical location to see the building in square perspective. Shift lenses are also rather expensive, so most people fix problems like this digitally, using Photoshop or similar programs.

Shift lenses take in big areas of a scene, and project image circles much larger than the film or image sensor. This lets you take shots with the camera perfectly level for parallel verticals.

If you were to take a photo with a normal lens and the camera level, you’d get a boring shot with a lot of ground and just the bottom edge of the building.

But a shift lens lets you move the picture area upwards within the image circle. This lets you isolate the building without having to tilt the camera. Verticals are preserved.

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▲ The Regent Street lights taken with a regular wide-angle

▲ The same scene taken with a shift lens. 24mm shift, full

lens. London, England. 22mm full frame. f/18, 4 sec. ISO 100.

frame. f/18, 4 sec. ISO 100.

 Shift lenses are commonly used for interior architecture photography as well, since converging verticals on walls and ceilings tend to look a bit strange.

Avoiding reflections Another common problem with architectural photography is that of mirrors in interiors. If you photograph the mirror straight on, the camera will clearly be visible. But if you move the camera over to one side, the reflection of the camera is hidden by the edge of the mirror. You can then use the shift lens to move over the field of view so that the image appears straight on. Presto—a photo taken by a reflectionless vampire!

 Visible reflection. The center of the lens was aligned over the center of the mirror, as you’d expect.

 Hidden reflection. This time the lens was centered over the picture that’s just to the right of the mirror, and the lens was then shifted back over. My image would only be visible now if the mirror extended further to the right than it actually does.

Of course this trick isn’t perfect. You’ll notice that the perspective isn’t identical between the shots. In particular, the chandelier and the objects on the rear shelf are in different positions in the reflected image. The only way around this is frankly a bit of Photoshop trickery.

Tilt-shift lenses Canon and Nikon both produce a number of tilt-shift lenses (older Nikon PC lenses are perspective correction, or shift, only). All are manual focus only because of the complexity of getting autofocus to work in such a lens.

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▲  A Nikon 24mm f/3.5 PC-E lens (left) and a Hartblei 80mm f/2.8 SuperRotator (right).

Another interesting lens is the Ukrainian-built Hartblei Super-Rotator, which can be contorted to strange tilt and shift angles and resembles some sort of awesome Eastern Bloc spaceship.

8.25

Lenses for video

One of the unexpected consequences of the rise of quality digital SLRs has been the transformation of video production. Traditionally, there has been quite a gulf between affordable consumer video cameras and expensive professional high-definition video. The former tend to offer fairly murky or indifferent video quality, whereas the latter can produce near film-like quality at the cost of a lot of money and the camera operator’s back. Everything changed in late 2008 with Nikon’s introduction of the D90 and Canon’s introduction of the EOS 5D Mark II. These two cameras brought high-definition digital video within reach of a new generation of filmmakers, transforming an entire industry. Soon everyone from student filmmakers to producers of big-budget TV shows were adapting digital still SLRs to video work, much to the astonishment of the camera makers, who had clearly initially viewed digital video on SLRs as just a check box on a feature list. While using DSLRs for video is a complex field and mostly beyond the scope of this book, the type of lens best suited for video production differs from your typical still-image lens. The key reason is focus.

 Video production with a DSLR: shooting the Toadlickers, a music video for Thomas Dolby.

Focus pulling With still images you normally acquire focus, then take a shot. If you’re doing sports, you might track focus on a moving object, but you’re still taking shots as you go. This is a process that can be automated fairly easily. With motion video and film, however, you’re likely going to be tracking focus smoothly and continually during a whole scene. Some cameras can track autofocus automatically, but smooth focus acquisition for a moving target is a difficult technical challenge. It’s also a matter of artistic intent that computerized systems can’t understand. It’s a basic filmmaking technique to adjust focus selectively for artistic or narrative purposes. For example, you might focus on one person in a scene, and then switch (or “pull”) focus to a second person when they start talking, thus drawing the viewer’s attention to the new speaker.

▲ These two shots of the Alhambra palace in Granada, Spain, show how the viewer’s attention can be directed from one part of a scene to another part, simply by altering focus. In a video there would be a smooth transition as focus moved from one distance to another.

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▲ A closeup view of the follow-focus mechanism. This particular lens isn’t intended for video work, and so a blue plastic flexible gear ring has been strapped to it. This allows its focus to be precisely controlled by the knob to the left. ▼ This shoulder-mounted rig transforms an ordinary DSLR into a rig capable of being used for follow-focus videography. It’s built around a standardized set of adjustable rails that are 15mm in diameter. All kinds of add-on devices can be clamped to these rails.

Still photography lenses are not usually suited for video. Traditional autofocus is great for nailing focus rapidly, but not so good for tracking moving objects. The noise of AF motors can also get recorded to the soundtrack. Newer technologies, like Canon’s silent stepper motor (STM) lenses are one option, but old-school manual-focus lenses are another. It’s pretty common to use old Nikon or Zeiss glass, adapted to a modern camera with an adapter ring (see section 9.2). There are, however, certain gotchas, such as the fact that Nikon’s focus rings operate in the opposite direction from most cinema lenses (see section 3.9). The Zeiss Planar lens used by Stanley Kubrick (see section 2.17) has been modified for compatibility with a follow focus system—the toothed gearwheel was added for precisely this purpose. Ergonomics are more of an issue. DSLRs are designed for still photography use, and so a whole industry has sprung up producing accessory devices and attachments that kind of convert a DSLR into a device that meets the ergonomic needs of filmmakers. It’s now even possible to buy electronic controllers that interface to autofocus lenses directly, allowing full manual control over their motors.

 This Zeiss Compact Prime CP.2 lens, though based around the same optical design as Zeiss-branded lenses for still cameras, is intentionally designed with film and video production in mind. It has an Arri PL lens mount (see Appendix A), it has separate toothed cogs compatible with geared focus and aperture changing mechanisms, it has distances clearly marked on a large ring (this model is in inches, but others are metric), and it has apertures measured in T-stops (see section 2.15) and not f-stops. It also has a massive price tag.

Prime lenses Prime lenses are typically what you want for video work with a DSLR. With primes you get fast glass, maximizing the amount of light striking the sensor. And you also get narrow depth of field when you shoot wide open.

PL, PV, and C mount lenses Nearly all professional movie productions employ lenses with Arri PL or Panavision PV lens mounts. Video cameras for closed-circuit purposes tend to use C-mount lenses. For more details on these mounts, check out Appendix A.

Focus breathing Focus “breathing” is a change in focal length that occurs when focusing. In other words, the field of view actually shifts as you focus on something. In still photography, it’s not usually a big problem. It can be a bit annoying when your telephoto suddenly has a shorter focal length when you focus from infinity to something close up, but it won’t adversely affect a finished image. But it can be a real problem with video. If you have a lens that changes the whole scene size when you pull focus, it can look pretty bad.

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8.26

Mirror lenses

Long focal length lenses are often physically long as well. And, before the invention of modern exotic low-dispersion glass, they also suffered from heavy chromatic aberration. Both problems were actually solved back in 1668 by Isaac Newton when he built the first working telescope that used reflective mirrors. Newton’s telescope contains a pair of hand-polished metal reflectors. These mirrors fold the light path in half and also magnify the image, because the larger surface is curved. Since no glass is used, there is no dispersion and thus no chromatic aberration.  This is Isaac Newton’s second reflecting telescope, “made with his own hands in 1671,” according to the plaque on its base. The object to the right is the now tarnished primary mirror. For his breakthrough work, Newton was offered a fellowship in the Royal Society of London for Improving Natural Knowledge (as it was then known), the British science organization that owns the telescope to this day. The telescope is shown here in the Reading Room of the Royal Society, London, England. 35mm full frame. f/2.8, 1/40 sec. ISO 100.

The same principles are used in the construction of mirror-based photographic lenses, though they are configured differently from Newton’s telescope design, which had an eyepiece on the side. Mirror lenses also contain additional glass elements and so are more correctly known as catadioptric (both reflecting and refracting) lenses. Nonetheless they offer the same benefits as Newton’s telescope— compact size, light weight, and good control over color fringing. Mirror lenses are often marketed to novices on the basis of their impressive focal lengths—500mm and up—and their low prices. Regrettably, while mirror designs make great telescopes they have significant limitations as photographic lenses. The fundamental problem is that the main mirror has an obstruction in the middle, covering the smaller, secondary mirror. This reduces the amount of light entering the camera, lowers the contrast, and induces a rather ugly form of bokeh. Essentially, all bright out-of-focus areas in the image end up taking on a ring shape, which looks noisy and cluttered (see section 8.18).

▲ Mirror lenses are instantly recogniz-

▲ This front view reveals how much

able. They’re generally short, wide, and

of the lens opening is obscured by the

stubby and have black discs mounted in

center mirror.

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the center of the main lens.

Mirror lenses tend to have apertures of f/8, meaning they’re only really useful under really bright light conditions. In fact, the apertures aren’t even adjustable because there’s no diaphragm. Fixed apertures mean that shutter duration, neutral density filters, and ISO settings are the only real ways to adjust exposure. So in short, while mirror or “reflex” lenses may seem like an attractive choice for affordable long telephotos, they usually wind up as a real disappointment. Always test one out first to make sure its limitations are acceptable to you. ▲ Light really bounces around inside a catadioptric lens, thanks to the reflective mirrors.

8.27

“Digital” lenses

(Mirrors are indicated in dark blue, and transparent lens elements in pale blue.)

Digital is definitely a popular marketing buzzword. Yet, like natural or improved, digital is often misapplied to the point of nonsensical meaningless. After all, what’s particularly digital about a camera bag or strap? Nonetheless, there are occasionally specific uses where digital might actually mean something in relation to lenses.

Coatings Digital sensor chips have different reflective properties compared to film. Accordingly, some lenses have special coatings, especially on rear elements, to minimize reflections between lens and sensor. It’s debatable how essential this actually is.

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Cropped sensors Most digital SLRs have sensors that are smaller than 35mm film. Some lenses designed for cameras with these small sensors, such as Canon EF-S, Nikon DX, and Micro Four Thirds systems might be labeled “digital” lenses.

Digital-only mounts Some lens mounts, such as Olympus Four Thirds or Fujifilm X, are only available on digital cameras since they were released after the makers stopped producing film cameras. These lens mounts may also incorporate certain features to accommodate characteristics of a digital sensor. For example, Four Thirds lenses are supposed to have “telecentric” optics. This means the light rays they project should be parallel, for more even illumination of a digital sensor chip.  Three Olympus lenses for Micro Four Thirds mirrorless cameras.

8.28

Dust

One of the biggest causes of heart attacks for a lot of perfectionist photographers is the discovery of dust inside a lens. That sinking feeling one gets upon gazing down a lens barrel of a favorite lens and finding a few bright specks of dust. So where does the dust come from, and is it a problem? There are essentially three different dust sources: dust that ends up inside the lens during manufacturing, dust caused by internal component wear, and environmental dust that comes in from the outside world. The first thing to keep in mind is that dust is inevitable. No lens is totally sealed against dust. In fact, lenses aren’t even assembled in completely dust-free environments because there’s no need to do so.

And the reality is that the odd bit of dust won’t make any difference to a photograph at all. A heavy coating of dust will obviously cause some real contrast problems, but that’s an extreme case. Having said that, it’s wise to keep lenses covered in heavily dusty environments, especially if the lens extends or contracts while focusing or zooming. Such “tromboning” sucks air in and out, bringing air and dust inside the camera and lens assemblies (see section 3.9).

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▲ Dust storms yield amazing qualities of light. But boy howdy are they tough on camera gear! The Trojan Horse, a huge wheeled wooden sculpture weighing 30 tons, emerges from choking clouds of alkaline dust. Built by Douglas Bevans and a cast of hundreds at the Burning Man arts festival 2011, Black Rock Desert, Nevada, USA. 28mm full frame. f/13, 1/320 sec. ISO 100.

8.29

Scratches

Scratches are another optical imperfection that can distress a lot of people. Here again it’s a matter of degree and location. A light scratch on a lens element, while depressing, isn’t likely to make a huge difference to a photo. However, if the scratch is very deep and wide, if

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it’s on a rear element (close to the film or sensor), or if it’s on a wide-angle lens, then it may show up as a darkened shadow in a photo. Scratches can also affect the overall contrast of a shot.

▲ My camera toppled over onto concrete pavement while doing a shoot, resulting in this heartbreakingly large gouge on the front element of a fisheye lens.

▲ The lens now yields photographs with dark scratch shadows in the lower left. La Grande Arche de la Défense, Paris, France.

So in short, while scratches are undesirable, their impact really depends on a number of factors.

8.30

Cleaning lenses

The best way to keep a lens clean is of course not to get it dirty in the first place. But that means you’ll miss a lot of photographic opportunities. So keeping lenses scrupulously clean is pretty important for good image quality. On the whole, camera glass is fairly tough because camera makers have devised sturdy coatings over the years. But lens glass is not invulnerable, especially to grit. Here are some points about cleaning lenses: f Use a rubber bulb blower to blow off any loose debris. Don’t use a pres-

surized canister that’ll probably drive dust deeper into your lens. And don’t blow with your mouth; you might inadvertently leave saliva bubbles on the lens and make things worse. f Next, sweep the lens lightly with a cleaning brush to dislodge any particles of grit or sand that could damage the lens.

f Finally, gently wipe the lens with a soft fluffy microfiber lens cleaning

cloth or a specialized tool like a Lenspen in a circular motion. Never reuse a dirty cloth, and never use a T-shirt or tissue paper. f Only use cleaning liquids if you absolutely have to. Apply the liquid to a cloth, and not to the lens directly, in order to minimize the risk of accidentally pouring loads of fluid into the device.

▲ Lens cleaning tools: a Pentax lens cloth, a Giotto

▲ Lenspens contain a carbon material that soaks up oils from skin,

Rocket air blower, a Spudz travel cloth, and two

allowing them to remove stubborn fingerprints.

Lenspens.

8.31

Keeping out the weather

The elements are not gentle to delicate photographic instruments. Dust, grit, rain, snow: all can wreak havoc on a camera or lens. Accordingly, more and more camera manufacturers are adding seals and gaskets to some of their products. These silicone rings and stepped joining surfaces can make a tremendous difference under inclement weather conditions. Push buttons, battery doors, sockets, and other potential openings can all be sealed. However, never forget that weather sealing and waterproofing are not the same thing. A weatherproofed camera would be useless on an underwater excursion—you need a proper underwater housing for that. Weather-sealed cameras include silicone gaskets at mating surfaces like lens mounts, so both lens and camera may need to be properly sealed. Some lenses also require a filter on the end for full sealing. Generally only midrange and pro gear is weather sealed.

▲ This weatherproofed lens from Pentax features a bright red silicone ring.

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 The Palace of Westminster, Britain’s Houses of Parliament, during a heavy snowfall. A burst of handheld flash was used to illuminate the falling snow. 19mm full frame. f/5.6, 2.5 sec. ISO 100.

8.32

Fungus

It’s hard to believe, but there are actually organisms that eat camera lenses. Amazingly, certain types of fungus can invade your prized possessions, gradually etching the glass with permanent tendril-like marks. Fungus is most prevalent in warm, moist climates, so residents of tropical or subtropical regions should always store lenses in sealed plastic containers with silica water-absorbing beads. More elaborate drying cabinets are also available. Once fungus has a slimy toehold, it’s nearly impossible to get rid of. When shopping for a used lens, be sure to shine a flashlight down the barrel and inspect all interior surfaces for telltale branching traces of fungus. ▲ This lens is home to a thriving colony of fungus.

8.33

Repairs

Old manual-focus lenses, while composed of numerous parts, are relatively simple mechanically. They can often benefit from the occasional clean, lubricate, and adjust (CLA) from an experienced repair technician. However, today’s electronic autofocus lenses include varying numbers of modules or subassemblies, some of which are factory aligned and selfcontained. This has a few consequences. First, regular maintenance is generally not needed or even really possible. Most photographers only have their lenses serviced when there’s a problem, or if they’ve been exposed to adverse conditions.

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Next, the most common types of damage—impact and liquid contamination—can easily affect multiple subassemblies. Liquid in particular is quite pernicious, as it can seep in and corrode part after part. Seawater and acidic drinks are especially lethal.

▲ The VR (image stabilizing) module from a professional-caliber lens is quite an expensive component.

▲ A technician repairs a large zoom lens.

Finally, repair costs can be quite high if an expensive subassembly like a stabilizer is damaged. It doesn’t take much sand or liquid to wreck a few internal modules and make a lens beyond economical repair (i.e., the parts and labor costs approach or exceed the value of the lens). Repairs of modern lenses can also require complex proprietary test equipment in many cases.

8.34

Infrared photography Ultraviolet

Most photography is done with ordinary visible light, but there’s also a ton of energy out there in the universe that we aren’t capable of seeing. Most of this electromagnetic energy, such as microwaves, radio waves, and X-rays, can’t be altered by lenses. But certain frequencies of ultraviolet (UV) and infrared (IR) energy can. While this energy may be invisible to us, it’s interesting to note that some animals can sense parts of it. For instance, many birds and insects can see into the ultraviolet spectrum, and some snakes can sense into the infrared spectrum via special sense organs. In terms of photography, UV is difficult because ordinary glass lenses tend to block it. UV-passing lenses for scientific applications exist, such as the vanishingly obscure fluorite and quartz UV Nikkor lenses, but they’re far too expensive for the average photographer.

Spectrum of visible light

Infrared

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However, IR photography is quite easy to do and affordable. In fact, most digital sensors have an innate IR sensitivity and have filters that block incoming IR. It’s often possible to modify a camera by removing these filters from the sensors. Such cameras can detect near-visible IR that’s produced by IR sources like the sun, a camera flash, or a light bulb. The IR is then reflected from other surfaces, just like visible light. It’s important to note that IR photography is not the same thing as thermal imaging, which is about sensing longwavelength IR directly. Thermal imaging is the technology for sensing the heat given off by bodies, as popularized by TV cop shows and the like. ▲ A self-portrait taken using a thermal imaging system. This kind of photo is not possible using a digital infrared camera. An installation at Edinburgh’s Camera Obscura, Edinburgh, Scotland.

 Vernazza harbor, shot first with a regular color camera. The second shot was taken using a digital camera modified for infrared sensitivity. Note how in IR the grass and deciduous trees appear to glow white and the ocean is very dark. The vegetation glow is the “Wood” effect, named after American inventor R. W. Wood, and occurs because such plants reflect a lot of IR light. Vernazza, Cinque Terre, Italy. 24mm 1.6x subframe. f/9.5, 1/250 sec. ISO 200.

But not all lenses are suitable for IR work. Some lenses have coatings that interfere with infrared, as shown below. The problem manifests itself as glowing hot spots at the center of the image. Unfortunately there’s no way of knowing what model lens will have the problem and what won’t—it’s a trial-and-error process of testing.  This shot has a bad infrared hotspot caused by incompatible lens coatings. Volterra, Tuscany, Italy.

Infrared distance scales Sometimes the distance scales on a lens (see section 3.9) will have supplementary values marked in red or with the letter R. These are for use with infrared film or digital infrared sensors. Because infrared energy has longer wavelengths than visible light, the focus marks on a normal scale will be incorrect. The red markings show the offset for infrared focusing. They’re often rather approximate because different infrared media detect different wavelengths, but they do serve as a guide. Typically they assume the use of now-discontinued Kodak HIE infrared film, which has an IR sensitivity of up to 900nm (nanometers). The marks may also have different positions for different focal lengths in the case of zoom lenses.

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8.35

The mystery of MTF charts

You’ll sometimes see small charts printed next to a specification table for a lens. These are usually modulation transfer function (MTF) charts, and they provide some details about the optical performance of a lens.

Some points about MTF There are a few important points to remember about MTF charts: f Each manufacturer tests its lenses according to its own criteria and test

regimens. You can’t reliably compare the MTF data of one maker with another. f Some makers actually publish theoretical MTF data and not real, empirical data. There’s nothing inherently wrong with this, but it does underscore how you can’t compare results cross-maker. f Even makers that base their published data on tested results will do so on a sample lens, not the one you have in your hand. And sample variation can be significant (see section 8.37). So what good are MTF charts? Are they totally useless? Not at all. They still offer useful guidance about how a lens behaves under certain conditions. Here’s how the charts work. The charts measure lens contrast in line pairs per millimeter (LP/mm). So 30 LP/mm would mean 30 pairs of lines (one black and one white in a pair) for every linear millimeter. Here is how to read them: f The vertical axis runs from 0 to 1 and indicates the amount of measur-

able contrast. Sometimes this axis runs from 0 to 100 percent. f The right-hand axis is the distance from the center of the lens to the f f f f f f f

edge, in millimeters. There are different curved lines, usually 8 in total. Some MTF charts have 10 lines or more. The colored lines indicate line-pair measurements taken with the lens stopped down to f/8. The black lines indicate measurements taken wide open. The heavy lines are taken, in this case, at 10 LP/mm, which is low resolution. The light lines are taken at 30 or 40 LP/mm, which is high resolution. The dotted lines are radial or sagittal measurements, which means the line pairs are drawn diagonally across the image frame. The solid lines are tangential or meridional, meaning they’re drawn at 90 degrees to the sagittal lines in this case.

Pro 135mm prime

Pro 70-200mm at 200mm

1.0

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Lens set to f/8

Sagittal

Sagittal

Meridional

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▲ Four sample MTF charts. These charts compare a high-end professional 135mm prime lens, a professional 70–200 zoom lens at the long and short positions, and an inexpensive consumer-level 90–300mm zoom lens.

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So, what does this all mean? How to interpret the charts? f The higher up (closer to 1) the lines are, the better the results. f The higher the heavy lines are, the better the lens contrast. You want

lines above 0.8 if you want a great lens. f The higher up the light lines, the better the sharpness. f The colored lines will always be higher than the black because lenses f f f f

always perform better when stopped down. If the colored and black lines are fairly close together, you’ve got a pretty good lens. Cheap lenses worsen in image quality when used wide open. Lines will always slope down to the right because lenses will be sharper in the center than at the edges. The flatter and more horizontal the lines, the better the edge-to-edge sharpness. The charts say nothing about color rendition.

8.36

A measurable obsession

A lot of people, judging by Internet posts, seem to spend a fair bit of their time photographing brick walls, rulers, and newspapers. They then post 100 percent crops to discussion sites, worrying about whether they have a “good copy.” In part this obsession with measuring is definitely due to the arrival of digital. In the days of film, it was actually somewhat difficult to examine a lens closely for optical faults. Photographic prints wouldn’t tell you much more than the quality of the lab’s printing equipment. You could use slide film and blow up a projection on the wall, but that’s obviously inconvenient. With digital, anyone can load up a shot at 100 percent view on-screen, see every tiny flaw, and panic. Accordingly, there’s something to be said about not getting too carried away about the specific performance of a lens. Most lenses are actually pretty decent these days. But no lens will be free of compromises. Now, I don’t want to sound dismissive. There are sometimes problematic lenses out there, and you probably want to do a quick test with a new lens to ensure that it’s working properly. It can be particularly worrisome if you’ve just spent a lot of money on a product and want to ensure that you’ve made a good investment. However, just photographing a newspaper—or even a proper sample chart—on the wall isn’t enough. To actually get meaningful results, you need standardized test procedures, as some sites offer online. But if that isn’t challenging enough, you’ve got to keep in mind there’s always sample variation.

 Some popular photographic performance charts.

8.37

Sample variation

As photographers we sometimes tend to obsess over details. The quest for the sharpest lens available consumes much of the available time of a lot of photographers, amateur and professional. For this reason, independent lens test results can be very popular. How better to decide whether lens A from maker X is better than lens B from maker Y? After all, lens makers are going to publish only lens data for their own product line, if they do it at all. The first difficulty with this can be summed up in two words: sample variation. Because of slight variations in manufacture, not every lens produced by a maker will be precisely the same as another, even between examples of the same lens model. The same applies to cameras. Tolerances are tight, but nonetheless one camera may have slightly different characteristics than another. This has several consequences. First, lens reviews on the Internet or elsewhere apply only to the specific lens that was tested, not every single lens out there. The second issue is that autofocus involves two separate devices: the camera and the lens. A lens may autofocus perfectly on one body but be slightly out on another.

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8.38

Micro focus adjustment

One of the consequences of digital photography, and the ability to view captured images at 100 percent detail, is the awareness of focus errors. Some combinations of cameras and lenses consistently miss the focus target—either front or back focusing from the desired point. In the past, it was usually possible to adjust a given camera and lens combination to ensure accurate focusing, but only at a service center. There was no way for a customer to calibrate a lens and camera together. Today, with the dominance of digital, many cameras are equipped with the ability to calibrate for a certain lens type. They may not be able to identify a specific lens, but they can be calibrated for a specific lens model.

▲ Micro focus adjustment menu items from Canon (left) and Nikon (right) cameras.

These micro focus adjustment options make it easier to get the highest quality possible for a given camera and lens combo.

8.39

Testing for focus errors

Testing for focusing problems can be quite a complex affair. Modern camera repair facilities have all kinds of expensive, calibrated machines for analyzing the performance of cameras and lenses. But we’re photographers, not scientific researchers (or at least I’m not). And, to be frank, my main concern is that my camera should be fairly reliable at achieving focus. It doesn’t have to nail focus to submicron precision. Accordingly, I find it useful to be able to test for focus at a very simple and pragmatic level. Appendix E of this book features a basic focus test chart

that you can photograph to determine if the autofocus mechanism on your camera is focusing to the front, to the back, or correctly. Essentially you just take some sample shots of the chart and examine the results on your computer screen. Here are three basic test result cases.

▲ This photo is correctly focused on

▲ However, in this photo the camera is

▲ This photo, by contrast, has back

the heavy horizontal line. The 0 is

front focused on the nearer numeral 1.

focused on the farther numeral 1.

uniformly sharp.

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CHAPTER 9

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9

Creative options: beyond the standard lens

“Anything people build, any kind of technology, it’s going to have some specific purpose. It’s for doing something that somebody already understands. But if it’s new technology, it’ll open areas nobody’s ever thought of before. You read the manual, man, and you won’t play around with it, not the same way.” William Gibson, The Winter Market

One of the fantastic things about photography is that you’re not limited to what you’re told to do by the instruction manual. And when it comes to interchangeable lenses, you certainly don’t have to stick to the officially branded and sanctioned manufacturer-made lenses. You can attach all kinds of optical devices, even homemade ones! This chapter explores some creative choices that go beyond brand-name lenses.

9.1 Manual-focus lenses ▼ Not merely a museum piece: lenses such as this Leitz Hektor from the early 1930s are easily used with today’s digital cameras.

Most modern cameras have an autofocus capabilities, but it wasn’t until the 1980s that camera makers finally devised reliable ways to achieve focus automatically. Until then cameras had always been focused by hand. You typically had to peer through a viewfinder and rotate a focus ring on the lens until things looked sharp. Manual-focus lenses served photographers well for generations, and there’s no reason they can’t be used today with modern autofocus or digital cameras. In fact, the rise of digital has transformed the fortunes of a lot of antique lenses. Old lenses from orphaned camera systems, once abandoned as useless dinosaurs, are suddenly commanding premium prices on the used market as people rediscover their unique optical qualities. These lenses aren’t simply gathering dust on collectors’ shelves, but are actually out there being used.

9.2 Adapting lenses to other camera systems As noted earlier, most cameras work only with lenses designed specifically for them. But what if you already have a collection of lenses? What if you want to adapt them to an incompatible system? The extent to which this is possible depends on the lenses and cameras in question.  East meets East. Contemporary Japanese (Nikon) electronics with 1970s East German (Carl Zeiss Jena) glass. An M42 to Nikon F adapter makes it possible to use this affordable but high quality 135mm lens with a digital body. However, note that this combo isn’t fully compatible. You can’t attain focus to infinity with this particular combination of lens and camera, making it suitable only for close portraits and macro shots.

Adapter rings In some cases, the lens may already have a mount that is fully compatible with the camera body. For example, a post-1977 Nikon F lens can be attached to any modern Nikon digital SLR. Likewise, any Pentax K lens can be attached to a modern Pentax K body. In other cases, the lens mounts will be incompatible, and it will be necessary to employ an adapter ring such as the ones below. These are precisely machined metal rings that have the camera body mount on one side and the lens mount on the other.

There are many complications as to whether or not a lens can be successfully adapted.

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Lens mount diameter Different lens mounts have different diameters. It’s obviously a lot easier to adapt a lens with a small mount diameter to a camera with a wide mount diameter rather than the other way around. A big lens designed for a medium-format camera might simply be too big for a small digital SLR. See a full list at Appendix C.

Image circle coverage All lenses are designed to cover an image area of a certain size. A lens designed for a digital camera with a tiny sensor, for example, will have a very small image area compared to a big medium-format camera. Generally, any manual-focus lens designed for a 35mm film camera will work fine on any modern DSLR—unless it’s a medium-format camera, of course. It is possible to adapt larger lenses, such as putting a medium-format lens onto a 35mm-equivalent DSLR, but there are certain issues aside from the obvious physical compatibility. You’re using only the middle of the lens, and the outer areas will not be contributing to the shot: basically a big crop factor. Still, this will mean the sharpest part of the optics will be used, and it does open up the possibility for lens shifting (see section 8.24) with the right type of adapter.  Nikon sells an adapter that lets you attach a Nikon F lens from one of its SLRs to a subframe Nikon 1 mirrorless camera. It’s of limited utility, though, as you end up with a massive 2.7x crop factor owing to the tiny sensor in the camera. Your super-wide 18mm lens, for example, will suddenly become a not so wide 49mm lens.

Conversely, if you put a lens with a smaller image circle onto a camera with a larger image area, then you’ll simply end up with dark areas around the edge of the frame.  A 4.5mm fisheye lens designed for a subframe camera, when used on a fullframe DSLR, produces results like this.

Lens registers All cameras have a fixed and precisely specified distance from the lens mount to the surface of the film or image sensor. This is the register, or the flange focal distance. If this distance is incorrect, you’ll experience focus difficulties, such as the inability to achieve infinity focus. There are four basic cases: f If the camera and lens have the same lens register distance but different

lens mounts, then you’ve got a problem. If you were to put a lens adapter ring, even a really thin one, between the camera and the lens, the lens would be further away from the camera than it should be, causing focus issues. f If the camera and lens registers are really similar distances, then you have the same problem. For example, Canon EF and Sony Alpha mounts have a 0.5 mm difference in register distance. That’s pretty thin for an adapter ring. f If the camera has a longer lens register than the lens, then you’ve got a problem again. Even if the lens were lined up flush against the mount, it’d still be too far away from the camera to work. The lens mount would essentially have to fit inside the camera’s mount for it to work, which is only possible if the lens is smaller in diameter than the camera mount. Alternatively the adapter ring could contain a distance-compensating glass element, which inevitably would reduce quality somewhat.

▲ The register is the distance from the lens mount to the image sensor or film.

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This is one reason Canon EF lenses can’t be adapted easily to other systems. An EF lens (register distance 44mm) would somehow have to fit inside a Nikon camera (register of 46.5mm), for example. It’s also why Canon FD manual-focus lenses (register of 42 mm) aren’t compatible with Canon EOS cameras. And it’s why Nikon F cameras can’t easily accept non-F lenses. In all these cases you could attach the lenses, but they would be useful only at near focusing distances; you’d lose infinity focus. f If the camera has a relatively short lens register, then you’ve got a winner! It’s easy to adapt a lens with a longer lens register because there’ll be plenty of room for a metal adapter ring. Canon EOS users are particularly lucky in this regard because the cameras have register distances of 44 mm, making it easy to adapt many lenses designed for other camera systems to fit EOS bodies. For example, Nikon F lenses have a register of 46.5 mm. All you need is an adapter ring that is 2.5 mm thick to adapt a Nikon lens to a Canon camera. Mirrorless cameras like Micro Four Thirds and Sony E system cameras have similar lens-adapting advantages. There’s a full table of lens registers in Appendix C.

Not all are created equal

▲ The aperture lever from a Pentax K lens sticks out quite a distance from the back of the lens.

A poorly made lens adapter, such as one with incorrect thickness, can cause focus problems. Worse still, an adapter that’s thicker on one side than the other, even infinitesimally, can cause uneven focus across the frame. Machining accuracy is one reason for the huge variation in price for adapter rings. Always test a newly acquired ring before committing it to a photo shoot. You don’t want to discover that focus was wrong after the fact.

Obstructions

▲ The lens on the left is a 20mm Nikkor, made before Aperture Indexing. On the right is the same model lens, modified for AI compatibility. Note the small holes in the “rabbit ear” coupling prong on the AI lens and the cut-down black rim.

Some camera mounts have physical barriers that get in the way when you try to adapt a given lens to another system. For example, Pentax K lenses have protruding aperture control levers that physically collide with the internals of full-frame Canon EOS cameras. However, EF-S mount Canon cameras, with their smaller sensors, have more room internally and so Pentax K lenses will fit them. A big problem for Nikon users is that “pre-AI” lenses made from about 1954 to 1977 have aperture rings that can interfere with and damage most modern (post 1990s) Nikon cameras. Such lenses can be modified (at a cost) to meet AI standards, but be very cautious before attaching an old manualfocus Nikon lens to a new camera. Another problem is lenses that protrude into the camera body and block the mirror from rising (an incompatible back focus distance). Some

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dedicated aficionados of manual lenses have been known to trim off the edge of their camera mirror to accommodate a beloved lens, but that is a pretty risky choice to make. Some cameras allow you to lock the mirror permanently in an up position, but this makes focusing a problem.

Compatible lenses have adequate clearance for an SLR’s moving mirror

Lenses that protrude too far into the camera can collide with the mirror ▲ This M42 lens has a small pin to stop

Setting the aperture Lenses with manual aperture adjustment rings are the easiest to adapt to other systems. You just attach the lens, rotate the aperture ring to the correct desired aperture, and take a shot. Automatic stop-down control won’t be possible, of course. Lenses with stop-down pins or levers may need adapter rings that push the mechanisms in. A handful of expensive adapter rings include small levers to operate the aperture mechanism, but most don’t. So if you’ve got a lens that lacks an aperture setting ring and an adapter that lacks aperture control, then you may only be able to use the lens at its default aperture setting. Nikon G lenses can be a problem for most inexpensive adapter rings, as can Pentax KAF lenses that stay permanently stopped down when not on a camera. Alternatively, on some systems with electrically controlled diaphragms, you can attach the lens to a compatible camera, stop the aperture down to

down the aperture.

▲ This tiny sliding switch allows you to choose manual aperture settings if you wish. A very convenient feature of Nikon D lenses such as this.

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your desired setting while pressing the depth of field button, then detach the lens while keeping the DOF preview button pressed. Some lenses (e.g., Canon EF) will keep the aperture permanently stopped down, and you can then attach the lens to another camera using an adapter.

Short throw; long throw Manual-focus lenses typically have a long throw. This means that you have to turn the focus ring quite a long way around in order to get a significant change in focus. The point of this design, of course, is to make it easier to achieve precise focus by hand. Autofocus lenses, however, are optimized for autofocus speed. This means they usually have a short throw: a relatively short turn results in a big change in focus. If they didn’t, then focusing would be very sluggish as the focusing mechanism (the helical) goes round. Unfortunately this design decision also means that it’s a bit fiddlier to use an autofocus lens for manual-focusing purposes. It’s easy to overshoot your desired focus point when turning the manual-focus ring by hand. Short throws are a particular problem for focus pulling in video (see section 8.25).

Automated systems

▲ The “00” in the aperture section of this Canon display indicates that the

Modern camera lenses contain computer chips, sensors, and electronic motors. Don’t expect these features to work properly on another system because they would need to convert the signaling protocols from one camera type to another, and very few adapters contain the necessary electronics. Essentially, all you usually get when you adapt a lens to another system is the ability to use the glass. You might get adjustable apertures if it’s a manual lens, as discussed earlier, but that’s it. That means no electronic aperture control, autofocus, image stabilizing, and so on. It also means that lenses with only electronic control over aperture and focus—lenses that lack direct mechanical coupling—can’t be usefully employed by incompatible camera systems.

camera knows that no electronic lens is present. So either a compatible lens

Chips and focus confirmation

is attached but not mounted properly (perhaps it hasn‘t been turned all the way) or there’s an all-manual lens installed.

While you can’t expect all the electronics to work, some lens mount adapters do contain little computer chips. The primary example is that of EOS cameras, though chips are available for other systems such as Nikon F and Micro Four Thirds. Many cameras are actually capable of focus confirmation with manual lenses. In other words, if you focus manually and half-press the shutter release, a little green dot will appear in the viewfinder to confirm that you’ve

got focus right. This functionality is optical and doesn’t rely on a computer in the lens. However, a camera will activate this function only if it thinks there’s a lens attached. And it thinks there’s a lens attached only if it can communicate with a lens computer. So that’s what these little chips glued to the adapter rings do—they fool the camera by telling it there’s a compatible lens attached. Newer adapter chips are programmable. The earliest ones just told the camera that there was a 50mm lens of some aperture setting attached, but the newer-generation chips let you, with some gymnastics, tell the camera what focal length and aperture you’re actually using. This information is then recorded in each photo’s EXIF metadata (see section 3.11). EOS users should also note that Canon has employed two separate methods for detecting the presence of a lens. Most EOS film cameras and earlier EOS 1D models require a small projecting screwhead on the side of the lens flange to trip a microswitch. If you have such a camera, and your lens adapter lacks this screw, then your camera won’t recognize the chip. One last point about chips is that I’ve heard anecdotally of camera electronics being damaged by misaligned lens chips. I don’t have any experience with that myself, but I imagine it is possible. So it’s worth checking to see if the chip that is glued to the lens mount matches the alignment of a real lens and that it isn’t loose.

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▲ A black circuit board containing computer circuitry is glued onto this Canon EOS lens adapter.

Sony and Nikon camera override Sadly, some cameras won’t work properly if they can’t detect the presence of a lens, which will always be the case with manual lenses. Many Nikon digital cameras, for example, will turn off the light meter. Some Sony cameras won’t release the shutter. Fortunately many, though not all, of these cameras do provide for an override. Better Nikon DSLRs have a menu item titled “Non-CPU lens data” that lets you input information about the manual lens that you’re using. Sony cameras have a feature called “shutter lock,” which prevents pictures from being taken when no lens is attached. If the display shows the “no lens attached” message, consult your manual. Some cameras require a combination of buttons to be pressed, whereas others have a menu item.

▲ An EOS lens mount with its microswitch screw.

Autoexposure ▲ Enabling a manual (non-CPU-

One important function of modern lens electronics is that they can tell the camera important optical characteristics of the lens. The camera can then factor these characteristics into its metering system for proper autoexposure.

equipped) lens on a Nikon DSLR.

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Without a chip, it’s possible that autoexposure will be incorrect on some cameras. Unfortunately it’s just a matter of trial and error to see if metering works properly with a given lens and camera combination. Generally speaking, you put the camera into manual or aperture priority (A or Av mode) with an all-manual lens. You may then need to apply some compensation manually. For example, I find some lenses need +2 stops of exposure compensation. Other lenses require no compensation.

Is it worth it? That’s the key question. As you can tell from all this detailed information, adapting manual lenses to modern computers isn’t always a straightforward process. I’d ask yourself the following questions: f Can the lens even be adapted to your camera? Is infinity focus possible? f Are you willing to put the extra time into using such a lens? The neces-

sity to fiddle with it may not be entirely compatible with snap-and-run photojournalism, for example. You wouldn’t want to be messing about with exposure compensation settings as the bride walks down the aisle. f Are there some specific manual lenses you really want to use? Is there some wonderful old portrait lens you want to try, or perhaps you’ve inherited a grandparent’s lens collection? Are you trying to replicate a classic photographic look? f Would an equivalent compatible autofocus lens give better quality anyway? While there are a lot of manual-focus nuggets out there, not every old lens offers good quality. f Is budget the primary concern? Maybe you need a fisheye only once a year, so buying a manual-focus fisheye at half the cost of a new autofocus model makes sense.  These inexpensive full-frame (Zenitar) and circular (Peleng) fisheye lenses are made in Russia and Belarus respectively. They both have solid metal barrels but have somewhat middling optics with a lot of chromatic aberration. But they’re much cheaper than the Asian-built competition, making them very attractive to hobbyists.

9.3 Focusing manually Whenever you attach an incompatible lens to your camera, you’ve got to rely on manual-focusing techniques. This was basic practice for years, but nowadays a lot of people aren’t very familiar with manual focusing and what is required.  Autofocus mechanisms often have great difficulty achieving focus in lowlight conditions. Sometimes manual focus is the best way to go, such as with this shot of Oia, Santorini, Greece. Although the photo was taken under a near full moon, it was extremely dark—both to the human eye and to the autofocus sensor. 24mm full-frame. f/4, 30 sec, ISO 200.

Focusing by eye is a definite skill that takes some time to master. However, there are technical aids that make it easier.

Focus screens Modern autofocus cameras aren’t really designed to accommodate manual focus, and so their viewfinders just have a smooth expanse of blankness, perhaps marked with little rectangles where the autofocus points are. However, this makes it difficult to know what’s in focus and what isn’t. Some viewfinders have textured ground glass or laser-etched plastic that yields a certain “snap” when things are properly focused. Less subtle are manual-focus assist aids, such as microprisms and split circles.

Microprisms Microprisms are essentially tiny pyramidal prisms cut into the viewfinder screen. When something’s out of focus, the image will appear broken up into little triangles. These recede when the image is focused. Microprisms

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don’t work very well with lenses that have small maximum apertures—the prisms just black out.

Split circles Split-circle, or split-image, viewfinders became popular in the late 1970s and ’80s. And they’re just that—bisected circular areas at the center of the viewfinder screen. You simply point the camera at a high-contrast line that’s perpendicular to the split circle’s line and then you adjust the focus. When the image is in focus, the object you’re focusing on will be continuous. When it’s out of focus, it’ll be broken in two. In my opinion, split circles are much easier to use than microprisms but they also have problems with long telephotos or slow lenses, for reasons of optical geometry.

▲ A doorway in Mykonos, Greece, as seen through a manual viewfinder. Left: the black diamonds in the micro-

The split can be horizontal, vertical, or diagonal. Some viewfinders have two splits, yielding four separate quarters. Some split-circle viewfinders have a supplementary ring of microprisms, known as a microprism collar.

prism collar and the broken line in the split circle indicate that this picture

Adding custom viewfinder screens

is out of focus. Right: the same scene correctly in focus.

Most consumer cameras these days do not support interchangeable or removable viewfinder screens. Cameras aimed at a professional market generally still do, and for these it’s easy to install your own screen. But it can be a fiddly operation for other models. It’s also very delicate—a scratched mirror or viewfinder, while not affecting photo quality, can be

very annoying to deal with. And it may be necessary to adjust the screen position, using a “shim” or gasket of a specific thickness, in order to ensure accurate manual focusing.  ▼ Using a manufacturer-supplied tool to install a split-circle viewfinder screen into an SLR.

However, because of the interest in rehabilitating old manual-focus lenses, there’s something of a cottage industry online selling viewfinder screens for modern cameras. These are often screens originally designed for film cameras, cut and trimmed to fit digital bodies.

Live View Custom viewfinder screens are great for SLRs, but they aren’t an option for mirrorless cameras. Screens also require a lot of fiddling to install and in some cases can throw off a camera’s light meter. The biggest technical breakthrough for accurate manual focusing is modern digital Live View. This is a system that shows you a real-time video feed of the image sensor. Not only can you zoom in to focus very precisely, but the LCD will show you what the camera’s sensor is actually seeing. Normal optical viewfinders, by contrast, either use a separate optical system or else send the image up through a mirror and prism. With such systems, you’re not quite viewing exactly what the imaging chip will record. The primary drawbacks with Live View are the additional demands that live video places on the battery and, in some cases, additional heating up of the sensor chip.

▲ Articulated back-panel LCDs are particularly convenient when used with Live View.

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9.4 Modern manual-focus lenses While there are plenty of classic and antique manual-focus lenses, there are also still companies manufacturing such lenses today. For example, while Zeiss no longer really makes still photography lenses, the company markets a line of manual-focus lenses with Nikon (ZF), Canon (ZE), and Sony (ZA) lens mounts. These lenses, which are equipped with computer chips and automatic aperture motors, are built in Japan by Cosina and Sony to Zeiss specifications and marketed as Zeiss products. Leica is another manual-focus standby. Its M series lenses, while designed for Leica’s rangefinder cameras, can be adapted to other makers’ digital cameras. ▲ A Zeiss Makro Planar 2/50 (50mm f/2) lens with a Nikon F lens mount.

9.5 Toy cameras and lo-fi photography An interesting trend has arisen in the past decade or so, roughly paralleling the rise of digital imaging: lo-fi photography. As camera makers rush toward ever-higher megapixel counts, filling camera bodies with more computing horsepower than a university lab of 20 years ago and devising advanced software techniques to eradicate lens aberrations, a new generation of photographers is turning their back on this kind of technofetishism. Many photographers, particularly a young generation steeped in the post-film world of disposable perfection, are experimenting instead with junk store cameras, scratched lenses, toy cameras, and film. There’s no room for formalism or test chart obsessions. Instead the emphasis is on evocative images—casual shots that encapsulate a moment or project a mood.

 A collection of plastic toy film-based cameras.

Lo-fi photography isn’t new, of course. People have been doing it for fun for years. Many pioneers in toy camera photography deliberately tried to harken back to the dreamlike photographs taken by the pictorialist photographic movement of the late 1800s. But in the 1990s, the rediscovery of cheap plastic toys like the legendary Diana and Holga cameras helped crystallize an underground photographic movement. Around this time, a pair of Austrian students stumbled across the Russian-built LOMO LC-A camera, imported the camera to the West, and created the “Lomography” marketing machine. (Note that there’s no connection between the Austrian-based Lomographische AG, developer and marketer of mostly Chinese-built products, and the Russian LOMO optical technology firm other than that the former borrowed the latter’s name.) Following are a number of visual traditions that converge around the lo-fi moniker: f Low-quality lenses. f Sharpness isn’t relevant. Blurriness is great if it captures

or evokes a mood. f Low or high color saturation. Either murky and moody, or synthetic and eye-poppingly bright color. f Dark vignetting around the edges of the picture. f Light leaks, causing streaks and lines in random ways. f Distortion. f Cross-processing (developing slide film in print chemistry or vice versa), which is a great way to liven up an image by introducing strange color shifts. f A rejection of formal style, symmetry, or classical rules of composition. f Either an effortless casual capturing of a moment or a studied attempt to replicate the same. f An emphasis on human interaction, humor, spontaneity, or ironic narrative. f Subjective perspective. Putting cameras in unusual places, emphasizing the camera’s role as a participant and not a dispassionately objective bystander. f The perception that film can be more genuine than digital, at least to people who can afford the processing costs. In a way, the lo-fi approach reflects the early days of 35mm cameras. The first 35mm cameras, such as the Leica, were revolutionary for their time because they were tiny portable devices that allowed for a far greater degree of freedom and spontaneity than big studio-bound boxes.

▲ Taken with a Lensbaby Composer with Plastic Optic.

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Arguably, to be properly lo-fi you should be shooting on film using the grungiest camera you can find. But there are degrees of faking it. The most common approach to faking it is to load a software program on a smartphone and have it process your camera phone shots, adding in faux filmic effects. While a bit cheesy, this approach has gained massive popularity, just because of the overwhelming ubiquity and convenience of camera phones. Another approach is to attach an old manual-focus or toy camera lens to a digital camera.

9.6 Diana lenses The Diana, and its sister the Holga, is a cheap all-plastic medium-format camera, originally produced in Hong Kong and sold as a novelty in the 1960s. Famous for their idiosyncrasies and generally poor optics, these toy cameras have developed quite a cult following. Replicas are sold today by the Austrian company Lomography. The Diana now has interchangeable plastic lenses for varying focal lengths and effects, and it’s possible to adapt the Diana lenses to Canon EOS and Nikon F cameras by means of a clip-on plastic adapter.  A Diana plastic lens, adapted for use with a DSLR.

The Diana lenses are fun, but keep in mind that many aspects of the Diana look can’t be replicated by putting a plastic lens onto a modern DSLR. The biggest problem is that a digital sensor, even a full frame one, is far smaller than medium-format film, so you get a huge crop effect. This limits the visual impact of the plastic lens considerably, particularly the famous vignetting. Also, the rough frame edges and random light leaks that are hallmarks of the cheap plastic toy camera are missing with digital cameras.

 Diana lenses ship in a variety of focal lengths.

▲ The Lens in a Cap is another lens that lets your expensive DSLR output soft, low-contrast images thanks to mediocre toy camera optics.

 Landschaftspark Duisburg-Nord, Duisburg, Germany. Full frame, 38mm “Super Wide Angle Diana Lens,” 6 seconds, ISO 200.

However, uncoated plastic lenses still have a unique look that works for a lot of shots. Take the view shown above of a decommissioned steel mill at the Landschaftspark Duisburg-Nord in Germany. The haze, soft focus, and halos of light around the backlit pipes give a timeless feeling to the photo.

9.7 A flexible approach: the Lensbaby Lensbaby is an American company that produces a very unusual line of optics. Instead of building lenses with fixed lens barrels, most Lensbaby lenses have adjustable or flexible barrels, making them a form of tilt lens. The lineup started with the Original Lensbaby, which consisted of a single lens element within a flexible ribbed rubber tube, like the hose of a vacuum cleaner. This made it possible to tilt the lens to any angle. To

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adjust focus you simply squeeze the tubing in or out, like the snout of some strange animal. While it’s not possible to shift the lens over much, because of the thickness of the hose, tilting is easy. The Original lens was superseded by the version 2.0 lens, which included coated optics. A variant of this design is still sold today as the Lensbaby Muse.  Author, blogger, and online activist Cory Doctorow at work in his office.

The main drawback of the hose design—the fact you have to hold the lens into position with your fingers—was addressed by the 3G version, which used a system of lockable metal rods to hold the lens to any angle or focus position. The result looks like some strange torture implement for very small aliens. A variant of this design, which is ideal for studio situations, is still sold as the Lensbaby Control Freak. Finally, the Lensbaby Composer was released, which replaces the springy hose design with an adjustable ball-and-socket system for tilt and a rotating end for focus. The Composer, like the 3G, holds whatever position you set.  Three generations of Lensbaby lenses. From left to right: the Original, the 3G, and the Composer with Optic Swap System.

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Lensbaby also brought in a system of interchangeable lens elements. It’s thus possible to swap out the elements from a Lensbaby barrel for different effects. Lens sets include uncoated single elements, coated glass elements with true apertures, plastic elements, fisheye optics, and so on. The Lensbaby is a very interesting lens system. It’s not going to compete with the sharpest Japanese or German precisionengineered optical masterpieces. What it offers instead is the ability to spontaneously adjust tilt, resulting in really unusual shots. It’s also possible to directly move the “sweet spot,” or the area in focus, around the image. The optical flaws of the lenses also have a certain quality to them, especially you’re when shooting wide open. Indeed, many of the Lensbaby optics demonstrate just about every optical aberration in the book, but that of course is part of their charm. The photos of London buses on the next page, for example, aren’t supposed to be razor sharp. In fact, the dreamy, hazy look is an integral part of the series. They’re also fun to accessorize. Many Lensbaby models include a set of black plastic washers that serve as aperture stops, but these can be replaced with any cutout you like, for creative bokeh (see section 9.8). Lensbaby lenses are popular with film and video production. For example, the 2007 French film The Diving Bell and the Butterfly employed a Lensbaby for a sequence in which the protagonist awakens from a coma and gazes fuzzily out at his doctors.

▲ Not all Lensbaby lenses are soft. The Lensbaby Edge 80 optic is an 80mm f/2.8 lens with an adjustable lens diaphragm. It’s quite sharp, but by tilting the lens it’s possible to cast sections of the image into soft focus.

▲ Adjusting the tilt angle of a Lensbaby 3G.

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▲ All aboard! This photo essay was shot in 2005 during the final three days that classic AEC Routemaster double-decker buses were in regular service on London’s streets. Taken on route 159 using Lensbaby optics.

9.8 Creative bokeh It’s easy and fun to induce bokeh effects deliberately. Bright out-of-focus areas in a photo will take on the shape of the aperture diaphragm, which sometimes can reflect the number of diaphragm blades inside the lens. Some lenses will have pentagonal or hexagonal highlights, and others circular. By shooting with the lens wide open and placing a simple card cutout right in front of the lens, it’s possible to create your own custom background highlight shapes. Since this technique relies on shallow depth of field it works best with standard lenses and large image sensors. A good combination is a 50mm prime lens on a full-frame digital camera. Following are some basics to keep in mind: ▲ Lensbaby lenses exploit the creative f Shoot wide open to ensure the maximum aperture possible. Otherwise,

bokeh phenomenon by selling a set of

the lens aperture will govern the appearance of the shot more than the custom aperture. f The effect won’t be very pronounced with slow lenses because they have a small maximum aperture. f Focus on something close to the lens. This ensures that the background will be pleasingly out of focus. f Find a scene with background highlights. City lights are one obvious example, as are small Christmas lights. f Choose simple shapes for your cutouts. Hearts, stars, and crescent moons work well. Complex shapes blur into shapeless blobs.

precut custom aperture discs as shown here. Blank ones are also provided so you can cut your own.

 A star-shaped paper cutout was used to give the background lights a star shape. 50mm full frame. f/1.8, 1/13 sec. ISO 100.

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9.9 Pinhole cameras

▲ Pinhole photos have a number of common characteristics: soft focus, near-infinite depth of field, a dreamy look caused by extremely long exposures and—if the film or image sensor is large enough—very wide fields of

Having written an entire book about lenses, it may seem odd I should mention that photography doesn’t actually require the use of lenses at all. But it’s quite true: you can take photos without a single piece of glass. The earliest experiments in image forming exploited the fact that a tiny hole in a light-tight box can project an image. These principles were discovered centuries ago and later became the foundation for the camera obscura. The basic idea has been around for a lot longer, though. The marine nautilus actually employs pinholes in its eyes! Pinhole cameras are easily made out of any light-tight container. People commonly use oatmeal containers, shoeboxes, cardboard barrels, entire rooms. Anything, really. A tiny, perfectly round pinhole is then installed at one end, across from the light-sensitive material. It’s also possible to buy plastic camera body caps with laser-pinholed squares of metal sheet or foil glued in. These essentially fit in place of a lens, allowing a normal SLR camera to take pictures pinhole-style. All you need is a tripod because pinhole shots require very long exposure times. Unfortunately, while the idea is nice in theory, the lens caps rarely achieve amazing results owing to the non-optimal focal distances involved. (The cool wide-angle look of pinholes, which image onto paper or large pieces of film, isn’t possible via a pinhole body cap.) Still, they’re an inexpensive way to experiment in pinhole work without much effort and, in the case of digital cameras, without any photochemical work.

view. However, a lens-cap pinhole such as this one has a fairly narrow field of view.

9.10

Detaching the lens

An interesting trick to try is the zero-budget approach of simply unlocking and detaching the lens, then holding the lens in position by hand. This lets you tilt and adjust the lens to any angle you wish, much like a proper tilt lens. You can even get some nice toy camera light leak effects by leaving a gap at one side. This type of photography, evangelized by photographer Luke Roberts1 as “freelensing,” can be quite fun. It generally works best with 50mm or so lenses, but because you don’t need a focus mechanism or even a compatible lensmount, it’s perfect for resurrecting an old lens you may have lying around. It’s also easiest to use with Live View. The primary risk is that of letting dust inside the camera assembly.

1 Check out Luke Roberts’s online group, flickr.com/groups/freelensing/

9.11

Fake anamorphic effects

Anamorphic optics are used in the production of wide-screen big budget movies. Because it’s really expensive to shoot wide-screen movies on 70mm film stock, regular 35mm film has traditionally been used for most Hollywood movies. The cameras contain a special optical device to squash the image to fit a 35mm film frame. The image is then stretched back to the normal wide rectangle shape when viewed because the projectors also contain anamorphic components. While anamorphic technology is a great way to make wide aspect ratios affordable for mass distribution, it has some interesting visual side effects as well. In particular, out-of-focus areas tend to be oval instead of round, and lens flare from bright light sources like car headlights tends to sear across the frame in straight lines. In fact, while these sorts of anamorphic artifacts are arguably image flaws, people are so used to seeing them in expensive movies that they’ve taken on a certain cachet of their own. Some cinematographers and videographers have taken to faking anamorphic effects even when not actually using anamorphic optics—just to make people think they’re watching a big-budget movie. A particularly cheap and cheerful way to simulate anamorphic lens flare, for example, is to stretch a simple piece of nylon fishing line across the lens opening or across the back of a lens. When stretched across vertically, the string will generally not affect the image except when a bright light source is present, and then brilliant horizontal streaking will occur. The effect, as shown in the cave photo at the opening of this chapter, won’t fool an experienced cinematographer for a second, but it’s fun to play with nonetheless.

9.12

Homemade lenses

They may not yield the kind of results you’d expect from the best lens makers in the world, but homemade lenses make for a pretty fun exercise. Basically, you can take a converging lens and, if it has a reasonably compatible image circle and focal length, attach it to a camera. It’s difficult to hand-make something as complex as a focusing helical system, so homemade lenses often have Lensbaby-style rubber tubes or simple cardboard barrels. They may thus have bend-to-focus or fixed-focus designs. The quality of a single-element lens like this isn’t great, but it fits the lo-fi aesthetic perfectly. It’s also really fun to take a lens system from a completely incompatible camera and modify it for use with a modern body. For example, the lens shown to the right is probably from an old projection system, and actually

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has a Petzval lens arrangement. It friction-fits inside a second tube, making a crude manual focus mechanism. Conveniently the outer diameter of this second tube just happens to fit perfectly inside a Nikon lens mount, making it simple to adapt to a Canon camera body with a Nikon to Canon adapter ring. Even entire camera bodies can sometimes be adapted. The Kodak Vest Pocket Camera (VPK) shown to the left was made in Canada in the 1920s for use with “Autographic” film. These tiny folding pocket cameras were in production for decades, and earlier versions were popular with servicemen during World War I. Autographic meant the camera had a little hatch for inscribing notes on the film itself—a very early form of image metadata. (“Hi, Mom! Here’s me and Bob in the trenches!”) Luckily for us, VPKs also have small circular back panels that were originally intended for cleaning and access. I’ve used this camera’s panel to interface with a simple M42 extension tube, attached to a DSLR via an adapter ring and Blu-Tack poster-hanging putty. High technology at its best! Focusing is achieved by extending the VPK’s bellows mechanism.  A portrait taken with the VPK camera arrangement shown above.

Conclusion

Lenses have been frustrating and delighting people since the dawn of photography itself. The inventor of photography, Nicéphore Niépce, was reportedly quite disappointed by some of the lenses he bought from opticians Vincent and Charles Chevalier. The main difference was that Niépce didn’t have Internet forums available where he could complain about his “bad copy.” But in all seriousness, this book has hopefully provided some background to the choices and compromises involved with photographic optics. There may not be the perfect lens for every situation, but there may be the perfect lens for you. And the universe of choice that opens up when you move beyond the kit lens is limitless. Photography is about the creative use of light-capturing tools, for which mastery over lenses is key. And, best of all, learning how to use lenses is a lot of fun!

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A

Appendix A: Lens mount systems

Countless lens mount designs have been used over the years. Each type represents a whole family or product ecosystem, and defines many characteristics of the camera that uses it. The following are some of the more common lens mounts that you might come across.

Arri PL Movie camera. The Arri PL (positive lock) lens mount was released in 1982 for use with 16mm and 35mm Arriflex movie cameras. It has since become something of an industry standard. For example, Canon sells a Cinema EOS digital video camera that uses only PL mount lenses. With more and more productions employing digital SLR cameras to record video, it’s become common to adapt PL-mount lenses to subframe DSLRs. You can even get custom-modified DSLR cameras that have their normal mounts replaced by PL. PL-mount lenses are not seen outside film and video production.

C-mount and CS-mount Movie and closed-circuit television (CCTV) cameras and microscopes. C and CS mounts are threaded mounts about an inch in diameter. They’re commonly used today for security video cameras, though they’re also used for microscope adapters. In the past they were popular with 16mm movie (cine) cameras. Most C-mount and CS-mount lenses have image circles too small, and back focus distances too short, to be of any use for digital cameras with larger sensors. However the rise in popularity of Micro Four Thirds has suddenly brought new life to lenses of this type, as it’s easy to adapt many of them to small-sensor mirrorless cameras. A lot of tiny lenses intended for ancient 16mm movie cameras are thus being rediscovered. Many vignette, but they often have other interesting optical qualities. Some have strange swirling bokeh, and fast speeds like f/0.95 are quite common.

Canon FL and Canon FD Film SLR. The Canon FL (1964–71) and FD (1971–87) manual-focus lens mounts were used by Canon 35mm film SLRs. Both became completely obsolete with the introduction of the Canon EF autofocus mount in 1987.

FL/FD lenses had a “breech lock” mechanism that used a rotating ring to tighten the lens against the camera body. Note that FL and FD manual-focus lenses are not compatible in any generally useful way with Canon EOS autofocus cameras. This is because of the difference in back focus distance. It is possible to adapt an FL/FD lens to an EOS camera with a ring, but unless a corrective lens is put inside the ring, you lose infinity focus. And the lenses always degrade image quality. Trivia note: three FL lenses, the AC series, had primitive autofocus, but this line was superseded by the EOS system.

Canon EF Film and digital SLR. In 1987 Canon took the dramatic step of creating a completely new lens mount with the introduction of the EOS autofocus camera system. The EF (electrofocus) lens mount was a technical breakthrough because it moved both electric aperture control and autofocus motors into the lens. While it cut off users of the older Canon FD lens system, it did lay the groundwork for a lot of future technological development in the company. Over the years Canon has expanded the abilities of the EF range, adding new features like silent ultrasonic focusing and image stabilizing while maintaining full compatibility throughout the line. Canon now sells one of the broadest ranges of camera lenses available, covering everything from affordable consumer products to expensive professional equipment. EF lenses are all fully interchangeable and compatible with all EOS cameras.

Canon EF-S Digital SLR. While the EF line has maintained constant compatibility over the years, Canon decided in 2003 to create a variant for use with subframe digital SLRs. There are three primary ways in which EF-S lenses differ from their EF brethren: f EF-S lenses have smaller image circles because they’re designed for 1.6x

crop cameras. f They have the potential for shorter back focus (hence the S in EF-S), which means that the rear element can be positioned closer to the sensor than on an EF lens. This permits the construction of cheaper wideangle lenses. f They come equipped with an EF mount variant. Both EF and EF-S lenses can fit an EF-S camera, but EF-S lenses cannot fit an EF camera. This avoids the problem of people fitting lenses with small image circles on a full-frame body and of lenses with short back focus colliding with an EF camera’s mirror.

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Contax G Film rangefinder. The brand name “Contax” dates back to German cameras from the 1930s. However, in 1975 the brand name was licensed from Zeiss by Japanese maker Yashica for a new line of manual-focus cameras and lenses. Such Contax/Yashica (C/Y) lenses can be adapted to certain cameras, such as Canon EOS. In 1995, the Contax G series was released by Yashica’s new owner Kyocera. The G1 and G2 cameras were accompanied by a line of extremely high quality autofocus auto-aperture lenses, mostly made in Japan under license to Zeiss. While the glass is highly respected, Contax G lenses are not easily adapted to any other camera system, because there are no mechanically linked controls for focus and aperture. There are adapters for Micro Four Thirds cameras, but there’s no aperture control and focus is via a tiny thumbwheel.

Four Thirds Digital SLR. In about 2000, Olympus and Kodak collaborated to produce a new universal lens mount for the digital age. The mount was designed from the outset to be purely digital, and so doesn’t support legacy film-based features, though as the cameras are SLRs moving mirrors are required. Although the format is mostly supported by Olympus, it’s also possible to buy Four Thirds cameras and lenses from Panasonic and Leica and lenses from Sigma. However they’re being phased out in favor of Micro Four Thirds. Four Thirds sensors are almost exactly the size of old Kodak Instamatic 110 film frames. Unusually for SLRs, they have a 4:3 image aspect ratio rather than 3:2. MYSTERY FRACTIONS The Four Thirds name is derived from old 1950s video cameras, which employed glass vidicon tubes. Such tubes were described in terms of their physical diameter in inches—1" or 2/3". But the usable imaging area of such tubes was only about 2/3 the diameter of the tube. Some digital sensors now use an absurd naming system that takes the imaging area of the chip, selects the approximate size of a hypothetical video tube that would have yielded such an area, and describes the result as a fraction in inches. The only logical reason for such a convoluted system is to hide the fact that these sensors are actually tiny—1/2.5" sounds much more impressive than the sad reality of 7.2mm, for example. And 4/3" sounds much bigger than 21.6mm. Why this arcane and arguably misleading system was used for marketing a digital camera standard is an even deeper mystery.

Fujifilm X Digital mirrorless. In 2012 Fujifilm announced a new digital mirrorless camera, the X-Pro1, and with it a new lens mount design. Fujifilm X is not to be confused with the short-lived Fujica X lens mount of the late 1970s. X-mount lenses are completely electronic, with neither focus nor aperture coupled mechanically. Thus, they cannot be used manually, independent of the camera. The mount has a short register distance of only 17.7mm.

Leica screw mount/L39/LTM Film rangefinder. The granddaddy of them all. The first still camera employing 35mm film was an experimental prototype built by German pioneer Oskar Barnack in about 1913. This “Ur-Leica” was the precursor of the first Leica camera, eventually released by Barnack’s employer Ernst Leitz in 1925 (hence the name Leica, from Leitz Camera). A revolution in tiny camera design, the Leica initially had a fixed lens. In 1930, a new Leica with a threaded lens mount 39mm in diameter, sometimes referred to as Leica thread mount, or LTM, was introduced. Since 1932, Leicas (except for Leica R) have been rangefinder cameras with separate lenses for the viewfinder and the film. The Leica IIIF shown below was made in the mid 1950s, and is shown with a collapsible Elmar lens. Since Leica rangefinders lack mirrors, the lens could slide back into the body, making for a very compact camera.

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Many other manufacturers built L39 lenses throughout the 1940s and ’50s, including Nikon (Nikkor) and Canon (Serenar). L39 mounts were also commonly used in photographic enlargers. Since 1999, screw mount lenses have been produced by Japanese maker Cosina under the Voigtländer name. Countless fantastic L39 lenses are out there, and most can be adapted fairly easily to many modern SLRs through the use of an adapter ring.

L39 enlarger lenses Film enlarger. Photographic enlargers are used in the darkroom to make prints from film negatives. For historical reasons, many enlargers have standard Leica-derived L39 lens mounts. Enlarger lenses are usually of extremely high quality—sharp and with a perfect flatness of field. However, they don’t make very good camera lenses because there’s no focus mechanism. Because you adjust focus on an enlarger by moving the enlarger head up and down, enlarger lenses lack focus helicals. The only way to get an enlarger lens to work on an SLR is to either move it back and forth to adjust focus or improvise some sort of bellows setup. The names of many enlarger lenses, such as the EL-Nikkor lenses from Nikon, have the prefix EL (it’s not a lens intended for a Spanish-speaking market or anything). The lens shown at left is a fairly typical 50mm lens, made by Rodenstock.

M39 Film rangefinder. M39 lenses have the same lens mount as L39, but because they’re designed for SLRs with moving mirrors, the lenses have a different back focus. Many older Russian SLRs employ M39 mounts.

Leica M Film and digital rangefinder. In 1954, Leica maker Ernst Leitz switched over to a bayonet-style lens mount with the introduction of the Leica M3 camera. And the firm has been using this 44mm lens mount ever since. All Leica M cameras, including the M8 and M9 digital bodies, can use Leica M lenses. A few other rangefinder cameras, such as the Konica Hexar and some Cosina Voigtländer Bessa cameras, also use this mount. The 28mm ElmaritM lens shown at left shows the characteristic curved Leica M cutaway on the mount.

Leica R Film SLR. In 1964, Ernst Leitz introduced a new SLR camera system to compete with the by-then dominant SLR products, mostly from Nikon. The Leicaflex cameras, eventually rebranded as Leica R, were never as successful as the company’s classic rangefinder cameras. The Leica R line, and its special bayonet lens mount, was discontinued in 2009. However the excellent R lenses are easily adapted to many modern DSLRs.

M42/universal screw mount Film SLR. The first modern SLR camera, the East German Zeiss Contax S, was introduced in 1949. This camera employed a threaded lens mount that was 42mm in diameter, and it laid the groundwork for the next quarter century of 35mm film SLR cameras. Countless film cameras, including well-known models such as the Pentax Spotmatic, employed this mount, making it the most universal lens mount ever seen. Many Russian manufacturers produced M42 cameras and lenses, such as the KMZ Helios 44M shown above-right. However, M42 is essentially obsolete today.

Micro Four Thirds Digital mirrorless. By 2008 it had become clear that there was market potential for mirrorless digital camera systems with interchangeable lenses. And so Olympus and Panasonic announced yet another format, Micro Four Thirds. This format has the same image area as Four Thirds and, with an adapter, can use Four Thirds lenses, but it has shorter focal-plane-to-lens-mount distance and a slightly smaller mount diameter. Micro Four Thirds cameras never have mirrors, and so are thinner and lighter than SLRs. Because of their size and short back focus, it’s possible to adapt just about any lens out there to a Micro Four Thirds camera, though the small sensor size can mean a significant cropping factor.

Minolta SR, MC, MD Film SLR. Between 1958 and 1985, Minolta sold lenses and cameras that employed the Minolta “SR” bayonet mount. These lenses were manual focus only, branded “Rokkor,” and typically of excellent optical quality. Rokkors are very

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popular with DSLR users. The SR mount was replaced by the incompatible Minolta AF mount.

Minolta AF Film and digital SLR. In 1985, Minolta released the first commercially successful autofocus SLRs. These cameras employed a new bayonet mount, Minolta AF, which was larger than Minolta MD. Minolta’s system placed the autofocus motor within the camera body itself, driving the autofocus mechanism via a rotating lever. While a great technical innovator, Minolta was eclipsed by Canon and Nikon. Minolta merged with Konica in 2003 and eventually abandoned the photography market in 2006. Konica Minolta’s camera technology was sold to Sony, which subsequently rebranded the Minolta AF mount as Sony Alpha. Minolta AF products were marketed under the name Maxxum in North America and Dynax in Europe.

Minolta V or Vectis APS film SLR. A lens mount designed for Minolta’s APS film cameras. Very few lenses were ever made, and they can’t easily be adapted to any other system owing to the short lens register distance.

Nikon F Film and digital SLR. The Nikon F system is arguably the most successful lens mount in history. Originally introduced in 1959 with the first Nikon F camera, the mount is a bayonet-style mount with a diameter of 44mm. Although the physical size and shape of the mount have never changed, Nikon has continually been making alterations and enhancements to the basic design. The Nikon F mount has evolved to support automatic metering, autofocus, image stabilizing, and all kinds of other technologies unimaginable in the 1950s. Compatibility is rather confusing, however. While all Nikon F lenses share the same exact mount dimensions, not all lenses can fit or work with all cameras. Most notably, very early pre-AI (before 1977) manual-focus lenses can actually damage modern Nikon cameras. And some post 1990s cameras won’t work with older lenses that lack electronic chips.

Nonetheless, a huge range of excellent glass is available to the Nikon F-mount user. And many are easily adapted to other systems. “D” type lenses, for example, are great since they have manual aperture control.

Nikon 1/CX Digital mirrorless. Introduced in 2011, the Nikon 1 line is Nikon’s first completely new lens mount design since 1959. It’s a series of very compact cameras with very small sensors and no mirrors. Nikon 1 lenses are not usable on Nikon F SLRs. Nikon 1 cameras can use Nikon F lenses with an adapter, though the tiny size of the sensor (which Nikon is calling the “CX” type) makes this fairly pointless.

Nikon DX Digital SLR. Nikon DX lenses are simply Nikon F-mount lenses with small image circles designed for subframe DSLRs. They can be attached to fullframe cameras, though they won’t cover the full 35mm frame, resulting in either large dark areas or a cropped frame.

Nikon FX In an attempt to reduce confusion, Nikon has started retroactively referring to full-frame technology as FX format. Of course, before the introduction of subframe DSLRs all Nikon F lenses were full frame, so this marketing practice can actually generate some confusion. In short, an FX lens is not a new development; it’s just a designation for any full-frame Nikon F lens.

Nikon IX APS film SLR. Nikon IX was a modified Nikon F mount, designed for the Nikon Pronea series of APS cameras. IX lenses cannot be attached to nonPronea cameras, though the cameras themselves could use Nikon F lenses.

Olympus OM Film SLR. Between 1972 and 2002, Olympus sold 35mm SLRs in its OM series. These cameras were good semiprofessional and advanced amateur products, with excellent lenses. Unfortunately, Olympus was not able to transition successfully to autofocus, and the largely manual-focus-only OM cameras were eventually discontinued. Olympus now focuses on consumer-level digital cameras.

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Panavision PV Movie camera. Panavision is an American movie supply giant. It owns all its own equipment and rents 16mm and 35mm cameras and lenses to professional filmmaking companies (watch the credits of many Hollywood movies to see the “Filmed in Panavision” logo). All of its lenses since the 1972 introduction of the Panaflex camera have been equipped with PV mounts. This proprietary mount, unique to Panavision, is 49.5mm in diameter with a register distance of 57.15mm. It uses a sort of breech lock system and is never used for still camera purposes. While mostly used solely with Panavision lenses and cameras, it is possible to adapt Panavision PV lenses to digital cameras using special custom-made lens adapters. This allows you to use, say, a Canon EOS body alongside Panavision cameras on a shoot. PV mount lenses are not seen outside film and video production.

Pentax K (PK) Film SLR. Pentax broke away from the M42 threaded lens mount in 1975 with the introduction of the Pentax K bayonet lens mount system. This allowed for faster attaching and detaching of a lens and faster lenses owing to a large lens mount. There have been a number of variants, but all Pentax K SLRs have been compatible with the Pentax K mount. Notably, Pentax ensured some degree of back compatibility by allowing K cameras to use M42 lenses with simple adapter rings.

Pentax KAF Film and digital SLR. Pentax successfully adapted the K mount to autofocus technology in the 1980s. Of the variants, KAF2 added some additional electrical contacts, and the KA2 mount lacks the autofocus drive and relies on in-lens motors. Modern digital Pentax K cameras also use the K autofocus mount.

Pentax Q Mirrorless digital. The smallest digital camera with interchangeable lenses at time of publication. The camera harkens back in a way to the tiny Pentax Auto 110 camera of the 1970s, though the mounts are incompatible. The Q system emphasizes pocketability and fun. In fact, some of the lenses available in the Q system include a plastic toy lens and a fisheye lens. However, there is only a modest selection of lenses available, and the Q sensor is also very small.

Samsung NX Mirrorless digital. Korean electronics giant Samsung introduced a line of cameras with interchangeable lenses in 2009 and with it a new lens mount known as NX. The line is unique to Samsung. The primary strength of the NX line is that the sensor is the same size as APS-C film, which is quite large for a mirrorless camera. A few lenses are available from Samsung. At press time, fellow Korean company Samyang is the sole third-party maker of NX-compatible lenses.

Sigma SA Film and digital SLR. Sigma, maker of many third-party lenses, also sells a number of SLR cameras. The digital bodies include innovative Foveon sensor chips, which employ layered image sensors that don’t rely on the traditional Bayer-pattern checkerboard grid. The Sigma SA design, introduced in 1992, is a bit unusual because it’s a sort of hybrid between Pentax K mechanics and Canon EF mount electronics. Sigma is the sole manufacturer of SA lenses.

Sony A-mount Digital SLR. The Sony Alpha (also known as A-mount or ) lens mount system is actually a legacy of the Minolta AF system that Sony acquired in 2006. It shares the same physical dimensions and is compatible with most of the Minolta AF electronics. Sony Alpha cameras can use all Minolta AF lenses. Sony has expanded the range to cover three basic types of SLR cameras: subframe DSLRs with APS-C sensors, full-frame DSLRs, and an unusual fixed-mirror system known as SLT. SLT cameras have “translucent” mirrors (they aren’t translucent at all because that technically refers to material that allows light but not images to pass through) that simultaneously pass light through to the digital sensor and reflect light up into the viewfinder for autofocus capabilities. Sony has also established a partnership with German lens maker Carl Zeiss and has produced a line of high-quality Zeiss-branded T* lenses for the A-mount system.

Sony E-mount Mirrorless digital. Designed for the Sony NEX mirrorless digital cameras. Sony has stated that it will not charge other

273

SAMSUNG NX

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LENS M O U NT SYSTEMS

makers to use this specification, and officially Carl Zeiss, Cosina, Sigma, and Tamron have said they support the format. Sony’s NEX cameras are extremely thin and compact, which makes their lenses look quite huge in comparison. Despite the tiny size of the cameras, they’re equipped with APS-C sized digital sensors.

T-mount Film SLR. In 1957, Japanese lens maker Tamron introduced a new threaded lens mount design, the T-mount. Similar to the M42 lens mount, but confusingly with a 0.75 mm thread pitch versus a 1 mm thread pitch, the idea was to produce a line of lenses that could be adapted to any camera with the right adapter ring. T-mount equipment is rarely seen today, except in the case of telescopes, which still often employ the standard for attaching cameras.

Tamron Adaptall Film SLR. Between about 1973 and 2005, Tamron sold a number of lenses with a special universal lens mount known as Adaptall or Adaptall 2. The idea was that it would only make Adaptall lenses and then sell separate adapters to let these lenses fit any make of camera. In other words, the Adaptall mount was intended solely for use on Tamron’s lenses, and no camera ever shipped with an Adaptall mount.

Tamron no longer makes Adaptall products but instead sells lenses with camera-specific lens mounts permanently attached.

Appendix B: Manufacturer-specific lens terms

Canon DO: Diffractive optics. Marked with a green stripe. EF: Electrofocus, full frame. Mount marked with raised red dot. EF-S: Electrofocus, short back focus. Subframe, white square. IS: Lens contains an image stabilizing motor. L: Lens is in Canon’s “luxury” professional lineup. Red stripe. MP-E: Unusual macro lens capable of 5x magnification. SF: Soft focus. Adjustable soft focus setting. Roman numeral: The nth version produced of the lens type. STM. Silent stepping motor optimized for video autofocus. TS-E: A tilt-shift lens compatible with EOS cameras. USM: Ultrasonic focusing motor. May have broken gold stripe. Fujifilm/Fujinon EBC: Electron Beam Coating. A type of vapor deposition for lens coatings. Leica Leica lists the maximum aperture (employing the German convention of a comma as the decimal mark), followed by focal length, e.g.: 2,8/28. APO: Lens is apochromatic to minimize color fringing. ASPH: Lens contains an aspherical lens element. Nikon/Nikkor AF: Lens can be autofocused by Nikon cameras that contain focus motors. AF-I: 1990s lens containing a small electric focus motor. AF-S: Silent Wave. Ultrasonic motor inside the lens. AI: Aperture indexing. Manual-focus design introduced in 1977. AI-P: 1980s manual-focus lens with an electronic chip for program mode. AI-S: 1980s manual-focus lens. D, AF-D: 1990s manual-focus lens that sends distance data to the camera. DC: Defocus control. Adjustable bokeh and soft focus. DX: Lens projects a small image circle for a 1.5x subframe sensor. ED: Contains extra-low dispersion glass. May be a pro or semi-pro lens. G: Lens lacks an aperture adjustment ring. IX: Lens designed for the old Nikon Pronea APS camera line. Micro, Macro: Macro lenses for closeup work.

B

275

CANON

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A PPEN DI X B

M A N U F A C T U R E R-S P E C I F IC L E N S T E R M S

N: Nano Crystal Coat lens coating. Usually badged with a red N logo. PC: Perspective control. Lens is capable of shift movements (but not tilt). PC-E: Perspective control with electronic aperture. Lens is a tilt-shift. VR: Vibration Reduction. Image stabilized. Olympus Zuiko/MZuiko ED: Contains extra-low dispersion glass. SWD: Supersonic Wave Drive. Ultrasonic focus motor. Pentax A-series: Pentax K manual-focus lens with automatic aperture control. AF: Autofocus capable. AL: Lens contains an aspherical lens element. D FA: Full-frame lens; compatible with digital cameras. DA: Designed for digital cameras with subframe sensors only. DA-L: Low-cost lightweight DA variant. DA or DA Star: High-end DA lens. DC: Direct current. Regular electric autofocus motor. ED: Extra-low dispersion glass. F, FA: Early autofocus lenses for film cameras. Full frame. FA J: Autofocus, but no aperture control ring on lens. Limited: Limited edition metal-bodied lens. SDM: Lens contains a Silent Drive autofocus motor. SMC: Super multicoated. WR: Weather resistant. Sigma APO: Apochromatic, to reduce chromatic aberrations. ASP, Aspherical: Lens contains an aspherical lens element. CONV: Lens can be used with a Sigma teleconverter. DC: Digital Compact. Designed for crop frame digital cameras. DF: Dual focus. Lens disengages manual-focus ring when autofocusing. DG: Digital Grade. For digital cameras; can also work with film cameras. DL: Deluxe. Low-end Sigma lens. EX: Excellence. Higher-end Sigma lens. HF: Helical focusing. Front element doesn’t turn when focusing. HSM: Hypersonic Motor. Ultrasonic focus motor. HZ: Hyperzoom. Consumer lens with 10x or greater zoom range. OS: Optical Stabilizer for image stabilizing. Sony, Minolta A or α: Sony A lens mount for Alpha DSLRs only. DT: Digital Technology. For use with cropped sensors only. G: Sony professional “gold” series lens.

NEX: E-mount lens for Sony NEX mirrorless cameras only. SAL: Sony Alpha mount lens. SAM: Smooth Autofocus Motor. Inexpensive, but not rough, focus motor. SEL: Sony E-mount lens for NEX cameras. SSM: Super Sonic Motor. Ultrasonic focus motor. STF: Smooth Transition Focus. Designed with soft bokeh in mind. T*: Equipped with the Zeiss T* lens coating. ZA: Zeiss Alpha. Autofocus lens with glass designed by Carl Zeiss. Tamron AD: Anomalous Dispersion. Specific glass type. AF: Autofocus capable. ASL: Aspherical lens element or elements. BIM: Built-in motor. Contains a lens focus motor. Di: Coatings better suited to digital cameras. Full frame. Di-II: For subframe digital cameras. HID: High index dispersion. Specific glass type. LD: Low dispersion. Specific glass type. SP: Super Performance. High-end Tamron lens. USD: Ultrasonic Silent Drive, ultrasonic motor. VC: Vibration compensation. Image stabilizing. XR: Extra refractive index glass. Specific glass type. ZL: Zoom lock to prevent zoom creep. Tokina AT-X: Advanced Technology Extra. Tokina’s higher-end lenses. DX: For cropped sensor digital cameras. FX: For full frame digital cameras. PRO: Adjustable clutch to switch from autofocus to manual focus. SD: Super low dispersion. Specific glass type. WR: Water repellent. A type of lens coating; not weatherproofing. Zeiss Zeiss employs the same aperture-first naming format as Leica. CP.2. Compact Prime. Built by Zeiss for cinema/video work. T* Equipped with the Zeiss T* lens coating. ZE: Built by Cosina to Zeiss specs for EOS cameras. ZF: Same, for Nikon F-mount cameras. ZM: Mostly built by Cosina to Zeiss specs for Leica M-mount cameras. Common across more than one maker IF: Lens uses internal focusing and doesn’t expand on focusing. Reflex: Catadioptric/mirror lens. RF: Rear focusing; doesn’t change length when focusing.

277

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C

Appendix C: Lens mount table

Name

Focus

Media

Years

Type

Diameter in mm

Register in mm

Image area

Notes

Arri PL

Manual focus

16mm and 35mm movie

1982–

Breech lock, 4 lug

54

52

Varies

For movie and videocameras only.

C- and CS-mount

Manual focus

CCTV, 16mm movie, and microscope

Screw

25.4

17.52 (C), Varies 12.52 (CS)

Useful for camera-to-microscope adapters. 16mm movie lenses popular with Micro Four Thirds users.

Canon FL

Manual focus

35mm film only

1964–71

Breech lock

42

36 × 24 mm

Not compatible with EOS cameras.

Canon FD

Manual focus

35mm film only

1971–90

Breech lock

42

36 × 24 mm

Not compatible with EOS cameras.

Canon EF

Autofocus

35mm film and digital

1987–

Bayonet

54

44

36 × 24 mm

For all Canon EOS cameras.

Canon EF-S

Autofocus

Digital only

2003–

Bayonet

54

44

22.2 × 14.8 mm

For most Canon EOS digital subframe cameras.

Contax G

Autofocus

35mm film

1995–2005

Bayonet

36 × 24 mm

Autofocus and auto-aperture rangefinder; difficult lens to adapt to other cameras.

Contax N

Autofocus

35mm film and digital

2001–05

Bayonet

36 × 24 mm

Employed by the first digital camera with a full-frame sensor. Not common.

Four Thirds

Autofocus

Digital only

2003–

Bayonet

44

38.67

17.3 × 13.0 mm

Olympus, Kodak, others. 4:3 image ratio.

Micro Four Thirds

Autofocus

Digital mirrorless

2008–

Bayonet

38

19.25

17.3 × 13.0 mm

Derived from the Four Thirds system, only purely mirrorless in design.

48

Hasselblad V Manual focus

Medium format

1957–

Bayonet

74.9

6 × 6 cm

Medium format only.

L39/LTM

Manual focus

Mostly 35mm film

ca. 1930–

Screw

39

28.8

36 × 24 mm

Used by most Leica rangefinder cameras, and Leica clones, before 1954.

Leica M

Manual focus

35mm film and digital

1954–

Bayonet

44

27.95

36 × 24 mm

Used by Leica M film and digital rangefinder cameras (not SLRs).

Leica R

Manual focus

Mostly 35mm film

1964–2009

Bayonet

47

36 × 24 mm

Used by discontinued Leicaflex and Leica R cameras.

M39

Manual focus

35mm film

1930s–

Screw

39

45.5

36 × 24 mm

Similar to L39, but with a longer back focal distance in order to fit SLR cameras.

M42

Manual focus

35mm film

1949–

Screw

42

45.46

36 × 24 mm

Known as “universal screw mount” owing to its popularity in the 1960s. Sometimes identified with Pentax cameras.

Mamiya M645

Manual and autofocus

Medium format

1975–

Bayonet

63.3

56.0 × 41.5 mm

Medium format. Film and digital, though image area of digital versions vary.

Minolta SR, MC, MD

Manual focus

35mm film

1958– ca 1997

Bayonet

43.5

36 × 24 mm

Incompatible with the Minolta AF system.

Minolta AF

Manual and autofocus

35mm film and digital

1985–2006

Bayonet

44.5

36 × 24 mm

Replaced by Sony Alpha.

Minolta V

Autofocus

APS film

1996

Bayonet

30.2 × 16.7 mm

Minolta Vectis APS film cameras only.

49.7

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L E N S M O U N T TA B L E

Name

Focus

Media

Years

Type

Diameter in mm

Register in mm

Image area

Notes

Nikon F

Manual and autofocus

35mm film and digital

1959–

Bayonet

44

46.5

36 × 24 mm

Multiple variants exist of the basic lens mount, adding features such as automatic exposure and autofocus.

Nikon IX

Autofocus

APS film

1996–2000

Bayonet

44

46.5

30.2 × 16.7 mm

Compatible with Nikon Pronea APS cameras only.

Nikon DX

Autofocus

Digital only

2003–

Bayonet

44

46.5

23.6 × 15.7 mm

Physically compatible with Nikon F, but for APS-C subframe DSLRs.

Nikon 1/CX

Autofocus

Digital mirrorless

2012–

Bayonet

17

13.2 × 8.8 mm

Nikon mirrorless; incompatible with Nikon F.

Olympus OM Manual focus

35mm film

1972–2002

Bayonet

46

36 × 24 mm

A very popular amateur camera system of the 1970s.

Panavision PV

Manual focus

16mm and 35mm movie

1972–

Breech-lock 49.5

57.15

Varies

For movie cameras only. Panavision rents, and does not sell, lenses.

Pentax K

Manual focus

35mm film

1975–

Bayonet

45.46

36 × 24 mm

The first Pentax lens mount to employ a bayonet mount.

Pentax KAF, KAF2, KA2

Manual and autofocus

35mm film and digital

1987–

Bayonet

45.46

36 × 24 mm

Pentax K with electronics and autofocus capabilities added.

Pentax 645

Manual and autofocus

Medium format

Bayonet

70.87

6.0 × 4.5 cm

Medium format only.

Pentax 6x7

Manual focus

Medium format

1969

Bayonet

84.95

6 × 7 cm

Medium format only.

Pentax Q

Manual and autofocus

Digital mirrorless

2011–

Bayonet

9.2

6.17 × 4.55 mm

The tiniest digital interchangeable lens camera system available at press time.

Samsung NX Autofocus

Digital mirrorless

2009–

Bayonet

23.4 × 15.6 mm

APS-C–sized sensor.

Sigma SA

Autofocus

35mm film and digital

1992–

Bayonet

Varies

Used on Sigma SLR cameras only.

Sony Alpha (A-mount)

Autofocus

Digital

2006–

Bayonet

49.7

44.5

36 × 24 mm and

Derived from Minolta AF. Both SLR and fixed-mirror cameras are available.

Sony E-mount

Autofocus

Digital mirrorless

2010–

Bayonet

46.1

18

23.4 × 15.6 mm

Very thin mirrorless cameras with APS-C–sized sensors.

T-mount

Manual focus

35mm film only

Screw

42

55

36 × 24 mm

Now seen mostly on telescope adapters.

Tamron Adaptall

Manual focus

35mm film only

1973–2006

Bayonet

50.7

36 × 24 mm

Tamron’s interchangeable lens system for film cameras.

Contax/ Yashica CY

Manual focus

35mm film only

1975–2002

Bayonet

45.5

36 × 24 mm

Zeiss AE/MM lenses with CY mounts are popular with hobbyists today, adapted to modern cameras.

46

42

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CH APTER OPENIN G IM AGES

D

Appendix D: Chapter Opening Images

Cover Our handsome cover bird is Petrie, a spectacled owl. Pulsatrix perspicillata is a species resident to Central and South America, where it lives in dense tropical forests. The fine hairlike feathers surrounding its beak are known as filoplumes, and are essentially sensory devices like the whiskers on a cat. Despite possessing incredible low-light vision, owls are quite nearsighted and rely on these feathers as feelers. Petrie hails from the Birds of Prey Centre in Bedfordshire, England. Special thanks to Emma and Mike for their generous assistance. 100mm macro full frame. f/7.1, 1/80 sec. ISO 200. The lens on the cover is the Canon EF 28-80 2.8-4L USM, one of the earliest ultrasonic L series lenses, introduced in 1989. It’s an unusual USM lens in that its focus ring is “fly by wire.” Introduction Spinning fire, Landschaftspark Duisburg-Nord. To reflect the history of the 1901 ironworks facility (now preserved as a public park), I created a whirling wheel of fire and sparks by attaching some steel wool to the end of a chain, igniting it, and then spinning it around. The blast furnace in the background was illuminated by handheld flash units. Duisburg, North Rhine-Westphalia, Germany. An extreme wide-angle lens was used. 16mm full frame, f/2.8, 15 sec. ISO 200. landschaftspark.de. Chapter 1 Mad scientist’s lair. Set design by Catie Max, Ed Saperia and the Clockwork Quartet, and NK Guy. Steamdrone by Will Segerman and Joe Schermoly. The Shunt Lounge and Theatre Company. London Bridge, London, England. 17mm full frame. f/6.3, 3.2 sec. ISO 100. clockworkquartet.com Chapter 2 Archer. This shot was illuminated solely by the two flaming light sources. A very fast lens set to f/1.2 was used, so the depth of field was extremely shallow. Highbury, London, England. 85mm full frame. f/1.2, 1/8 sec. ISO 200. Chapter 3 Blast furnace 5 of the former Meiderich Ironworks. The site closed in 1985 and is now part of Landschaftspark Duisburg-Nord, a fantastic public park focused on memorializing Germany’s industrial heritage. Duisburg, North Rhine-Westphalia, Germany. Landscape architecture by Latz+Partner. Lighting design by Jonathan Park. 16mm full frame. f/7.1, 30 sec. ISO 200. landschaftspark.de / latzundpartner.de / studiopark.co.uk

Chapter 4 Rainforest Tree, a 40 meter/130 foot sculpture designed by Wolfgang Volz and constructed by Clostermann Entertainment. Located within the Gasometer Oberhausen, a vast 100 meter/330 foot tall decommissioned gas storage tank in Oberhausen, Germany, now used for exhibitions and events. 16mm full frame. f/6.3, 30 sec. ISO 200. gasometer.de Chapter 5 Piazza del Campo, the main square of the medieval city of Siena. This photo was taken from atop the Torre del Mangia, a 290 foot (88 meter) tower next to the town hall. A full-frame fisheye lens was used to take in the sweeping panorama, the site of the annual Palio di Siena horse race. Siena, Tuscany, Italy. 16mm full-frame fisheye, full-frame camera. f/8, 1/200 sec. ISO 200. Chapter 6 Meoto Iwa, the Wedded Rocks. A heavy rice straw rope links these two small near-shore rocks, representing the sacred bond of marriage. This is cool, but I have to say the woman rock is really unfairly small. Futami, Mie, Japan. In order to transform the ocean waves into a ghostly haze, an 8x neutral density filter was used along with a very low ISO and a tiny lens aperture. This allowed a comparatively long exposure of 20 seconds in full daylight. 50mm full frame. f/22, 20 sec. ISO 50. Chapter 7 Steps of Montmartre. Rue du Mont-Cenis. Montmartre, Paris, France. 17mm 1.6x subframe. f/9.5, 15 sec. ISO 100.

Chapter 8 The Temple of Transition. A huge temporary wooden structure built by the International Megacrew at the Burning Man arts festival 2011. Black Rock Desert, Nevada, USA. 24mm full frame. f/8, 20 sec. ISO 100. burningman.com / internationalartsmegacrew.com Chapter 9 Valentine Cave is a lava tube formed over 30,000 years ago. Flows of molten lava created hollow tube-like caves when the surface crusted over while lava continued to flow below. Lava Beds National Monument, California, USA. The simulated anamorphic lens flare is described in section 9.11. 29mm full frame. f/5.0, 2 sec. ISO 100. Appendices The Puente Nuevo at sunset. Ronda, Andalusia, Spain. This bridge was completed in 1793 and spans the deep El Tajo gorge. 17mm full frame. f/5.6, 1/125 sec. ISO 100.

281

CH APTER OPENIN G IM AGES

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A SIM PLE FO C US TEST

E

Appendix E: A simple focus test

Here’s a simple focus test that you can use to confirm if your digital camera and lens combination is basically working properly for autofocus. See section 8.39 for more detailed information. 1.

Open this book to the test chart on the following page and use clips to hold it open. If the book is inconveniently uncooperative, or if you’re viewing this in eBook format, you can download a PDF of the test page from rockynook.com/focustest and print it out on a good quality printer. 2. Rest the chart on a solid surface, such as a wooden board. Otherwise the paper may flex, skewing the results. 3. Prop the chart at a roughly 45° angle. 4. Make sure there’s enough light for autofocus to work. Sunshine or a bright desk lamp works best. 5. Set a camera on a fixed support, such as a tripod. Make sure the camera is level and that the center of the lens lines up with the center target of the test chart. 6. Look through the viewfinder and ensure that the horizontal line on the chart is at the center of the viewfinder. Set the central focus point. 7. Take some autofocus test shots with the lens set to its widest aperture. Use a self-timer or a handheld remote release to avoid jarring the camera and thus blurring the shot. Try taking some shots with manual focus as well as autofocus for comparison purposes. 8. Load the photos into your computer and view them at 100 % magnification. 9. Examine the numerals above and below the target line. The numbers should be equally sharp or blurry on either side. If either top or bottom is consistently blurry, then your autofocus system is incorrectly focusing to the front or back. See the examples in section 8.38. 10. Compare the results from more than one lens to see if any focus errors are specific to the camera or to the combination of camera and lens. 11. If your camera has micro-focus adjustment, then adjust the lens to correct for the error. Repeat the test as required. 12. If your camera doesn’t have focus adjustment, then you may need to take the camera and lens to a repair facility for proper calibration.

Simple Focus Test Chart Also found at rockynook.com/focustest

20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

283

A SIM PLE FO C US TEST

284

ACKN O WLED GEMENTS

Acknowledgements

Technical reviewers: Paul van Walree, Meritt Reynolds, Roger Cicala, Willem-Jan Markerink. While their advice is gratefully appreciated, any errors remain my own.

Models: Gray Akotey, Hannah Ballou, Anisah Bhayat, Liana Bloom, Beckie Bonfield, Tom Burns, Aran Dasan, Cory Doctorow, Marie Favre, Catherine Francey, Catie Max, Diana Gershom, Everick Golding, Ethan Guy Sobieski, Ant Hatcher, Muna Hasaballah, Nicholas Immaculate, Luther Knight, Kathleen Meyts Coba, Eva Ng, Alice Peperell, Sabine, Jennifer Savage, Alan Sherwood, Daniel Spencer, Ebelah Tate, Martina Ziewe.

Special thanks to: Publisher Gerhard Rossbach and everyone at Rocky Nook—Joan Dixon, Matthias Rossmanith, and Petra Strauch—for patiently making this project a reality. Fiona Haser and Piers Bizony, Muriel Guy, John and Sanae Guy, Naomi Guy and Gabe Sobieski. George and Sally Low. Richard Shepherd of Canon Europe, Uxbridge, England. European arm of Japanese camera maker Canon. canon.com Richard Damery of Aperture Photographic. Purveyors of new and used professional camera equipment. London, England. apertureuk.com Jan Harlan and the Stanley Kubrick Archive. Helga Jursch-Kappl, Carl Zeiss Optisches Museum Oberkochen, Oberkochen, Germany. zeiss.de Paula, KC, Barry, and Nick of Fixation, professional camera repairs and rentals. London, England. fixationuk.com Joanna Hopkins, the Royal Society, London, England. royalsociety.org Graham Wren, Dave Titchen, and Paul Coulthread of Wex Photographic, British mail order photographic supplies company. warehouseexpress.com Meritt Reynolds of Ripplon Software, makers of LensForge, optical modeling and design software for OS X. ripplon.com Paul Reynolds, lens distributor Sigma UK. sigma-imaging-uk.com Nahum Mantra, Luke Cooper, Lee Jones, and the whole team at the

Shunt Lounge and Theatre Company. London, England. RIP Shunt Lounge – the vaults were the most magical place in London. shunt.co.uk Colby Gutierrez-Kraybill, Hat Creek Radio Observatory. Hat Creek, California, USA. www.hcro.org Chris, Mike, and Marina at Optical Support, lens repair specialists and Steadicam supplier. London, England. opticalsupport.co.uk Lawrence Wiles of Teamwork Digital, supplier of professional photographic equipment. London, England. teamworkphoto.com Maddie Gower and Charlotte Faulkner, Escapade PR for Pentax UK. Richard Wolfe. CMC PR for Fuji UK. Keri Friedman, Lensbaby. Portland, Oregon, USA. lensbaby.com Hannah Brown, Lomography. London, England. lomography.com Ryan Keating, Lenspen. Vancouver, BC, Canada. lenspen.com Kiran Umapathy, Photojojo. US supplier of photographic accessories and unusual equipment. photojojo.com Jane Nicholson, Intro 2020 photographic equipment importers. Maidenhead, Berkshire, England. intro2020.co.uk Ed Saperia and the Clockwork Quartet. London, England. clockworkquartet. com Nicholas Immaculate, haute couture costumes. London, England. Alice Peperell. London, England. alicepeperell.com Makeup by Kate Sheehan. Burning Man images courtesy Black Rock City LLC. Lee Anna Mariglia, Marion Goodell, Andie Grace, and Heather Gallagher. San Francisco, California, USA. burningman.com Douglas Bevans, Alaya Boisvert, Dan Fox, Jay Mosher, Eric Swenson, and the entire Trojan Horse team. trojanhorse2011.com Mike Ross and the Big Rig Jig team. mikerossart.net Rebecca Anders, Jess Hobbs, Peter Kimelman, and the Temple of Flux team. temple2010.org Chris Hankins, Diarmaid Horkan, and the entire International Megacrew. internationalartsmegacrew.com Arne Quinze, Jan Kriekels and the Uchronians. uchronians.org Musée des Arts et Métiers, Paris, France. arts-et-metiers.net Catie Max, theatrical and film props extraordinaire. London, England. Gasometer Oberhausen. Oberhausen, Germany. gasometer.de Lava Beds National Monument. California, USA. nps.gov/labe The British Museum, London, England. britishmuseum.org Thomas Dolby. thomasdolby.com Ant Hatcher and the Original African Indianz. originalafricanindianz.com Richard Daniels, Senior Archivist for the Stanley Kubrick Archive. University of the Arts London, London, England. www.arts.ac.uk Tim Heptner, Deutsches Filminstitut. Frankfurt am Main, Germany. deutsches-filminstitut.de

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ACKN O WLED GEMENTS

Chuck Westfall, Canon USA. Lake Success, New York, USA. Birds of Prey Centre, Old Warden Park, near Biggleswade, Bedfordshire. birdsofpreycentre.co.uk Donjon des Aigles bird park. Beaucens Castle, High Pyrenees, France. donjon-des-aigles.com Dalila Wallé, Museum Boerhaave; the Dutch National Museum for the History of Science and Medicine. Leiden, the Netherlands. museumboerhaave.nl Edinburgh’s Camera Obscura and World of Illusions, Edinburgh, Scotland. camera-obscura.co.uk Claire Nash, Diana Nash, Beckie Bonfield, and Orinoco Flow of Kemnal Manor Stables, Chislehurst, England. Canestrelli Artisanal Mirrors. Dorsoduro, Venice, Italy. www.venicemirrors. com H.R. Owen Ferrari Atelier. Knightsbridge, London, England. hrowen.co.uk Ferro & Lazzarini glass factory. Murano, Italy. www.ferrolazzarini.it Budavéri Labirintus: the Labyrinth of Buda Castle, Budapest, Hungary. labirintus.com/en/1 Hotel Everland Paris (2007–2009) appears courtesy Lang/Baumann. Burgdorf, Switzerland. everland.ch The Natural History Museum, London, England. nhm.ac.uk Arundel Cathedral, Arundel, England. arundelcathedral.org Galeries Lafayette, Paris, France. galerieslafayette.com Laser fluorescence optical design by Yellowcloud. flickr.com/yellowcloud Desert easy chair courtesy Stuart Gibson and the Star****ers Oasis. Diagrams on pages 178, 179, a based on data and original diagrams created by Pierre Toscani. pierretoscani.com Additional thanks to Taz Alexander, Julie Atwood and Matthew Wilson, Alessandro Barbini, Kirk Bridger, John Cater, Ivan Cockrum and Mary Saucier, Cory Doctorow, Marie Favre, William Gibson, Barbara Harrison and the Barge St Bride, Diego Iaconelli, Chris Jones, Doug Jones, Martin Lee, Mary McMenomy, Jake Messenger, Rick Mitra, Shamil Morjaria, Alice Peperell, Fahmida Rashid, Christoffer and Shoko Rudquist, Jamie Sabau, and Gunther Schmidl. And as always, ultra-special thanks to Jennifer for putting up with so much so I could get this book done.

Author’s Note You may notice that some lens brands are better represented in this book than others. This isn’t out of any particular bias on my part, but because some makers were more willing than others to participate in the making of this book. All trademarks are the property of their respective owners. No endorsement of any products or services mentioned herein is intended by the author or the publisher, and all products are shown for illustrative purposes. Some products were purchased by the author, others were loaned by manufacturers, and a few were donated. All text, photographs, and diagrams are by the author. The sole exception is the opening quotation of chapter 8, which is reprinted with the kind permission of William Gibson. No stock images were harmed in the making of this book.

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GLOSSARY

Glossary

These definitions are in the context of cameras with interchangeable lenses and are relevant only to that context. The terms may thus have other meanings that are not discussed here. 35mm. The most popular film format in history; 35 mm in width. Still frame images are usually 24 mm by 36 mm in size. aberration. Any deviation of a lens, from a theoretical ideal that results in diminished performance or a loss of optical quality. advanced amateur. Describes a midrange product aimed at the enthusiast who can’t afford high-end professional gear but who wants better build and optical quality than that provided by a consumer device. anamorphic. A technology used for making movies. Allows wide-screen films to be recorded onto regular 35mm film. Special lens elements compress (in the camera) or decompress (in the projector) the image horizontally. aperture ring. A rotating ring on a lens barrel. Used to adjust the size of the aperture. On a manual lens this is a simple mechanical linkage. aperture. Inside a lens, an opening through which light can pass and that can usually change size to control the amount of light entering the lens. Analogous to the pupil of an eye. apochromatic. A lens designed to reduce chromatic aberration. APS-C. APS, the Advanced Photo System, was a consumer film format of the 1990s. One of its image sizes was known as APS-C, and many digital sensors approximate this film frame size today. aspherical lens. A lens element that is not a cross-section of a sphere. In other words, it has a variable curvature of radius across its surface and should reduce spherical aberration. astigmatism. An optical aberration in which the spokes of a wheel-shaped image may be in focus or the rim of the wheel, but never both. auto-exposure. A light meter, linked to a computer, that determines the correct exposure for an image. The AE system can set shutter speed, aperture, digital ISO if available, or a combination of the three. autofocus. An optoelectronic technology that permits cameras and lenses to acquire and set focus automatically.

barrel. A usually cylindrical plastic or metal tube containing the lens elements that make up a camera lens. barrel distortion. A type of geometrical distortion in a lens that causes a rectangular or square grid to appear to bulge outward, as though it were a barrel. bayonet mount. The most popular style of lens mount today. A circular mount with three or four lugs or claws. The lens is inserted into the camera and rotated a partial turn to lock into place. bellows. Flexible accordion-like tube, made of cloth, plastic, or leather, that connects the lens and camera. Rarely seen today except on some macro extension systems. between-the-lens shutter. A shutter that’s built into a lens assembly and isn’t positioned inside the camera body next to the focal (image) plane. beyond economical repair (BER). An item so badly damaged that the cost of repairs near or exceed its worth. biconcave. A lens element that is concave—curves inward—on both sides. biconvex. A lens element, like a simple magnifying glass, that is convex— curves outward—on both sides. block diagram. A two-dimensional drawing representing the type and arrangement of lens elements inside a camera lens. body. A camera, typically implying the part of the camera containing the film or light sensor but not the lens. bokeh. The smoothness or roughness of the out-of-focus areas in an image. brassing. Physical wear or damage to a metal component where paint or a protective coating is scratched or worn off, revealing bare metal beneath. breech lock mount. A lens mount characterized by the lens being lined up against the camera body and held in place while a rotating pressure ring is turned to fasten the lens. build quality. The standards of physical construction to which a lens is built. camera. A light-tight box containing film or a digital image sensor and used for recording photographic images. catadioptric. A mirror lens containing both reflective surfaces (mirrors) and regular refracting glass elements. CCD. See charge-coupled device.

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central processing unit (CPU). Sometimes refers to a computer chip installed inside a camera lens, and sometimes refers to the main computer inside a digital camera. charge-coupled device (CCD). A common type of electronic image sensor technology, though one waning in popularity. chip. An electronic component, made from silicon and other materials, usually with some digital function. Often in reference to a computer chip installed within a camera lens. chromatic aberration. A type of aberration, caused by dispersion, in which high-contrast lines have bright color fringes. circle of confusion (CoC). The largest circular spot indistinguishable from a point to the viewer. Essentially the smallest point that can be imaged by a lens when it’s precisely focused. circular fisheye. A fisheye lens that records 180 degrees across the short length of a rectangular frame of film, resulting in a circular image bordered by black triangles in the corners. clean, lubricate, and adjust (CLA). Basic maintenance of a mechanical device, such as a camera or lens. close focus distance. The nearest distance to the lens at which it’s possible to achieve focus. close range correction (CRC). Unit that contains internal moving lens groups that shift for improved near focusing. Nikon term; called floating elements by Canon. clutch focus. A manual mechanism that engages or disengages autofocus by sliding a lens ring. CMOS. See complementary metal-oxide semiconductor. coating. A thin material applied to the surface of a lens in order to reduce reflections and flare. color. The human experience of sensing certain wavelengths of light energy. coma. A lens aberration in which points of light appear comet shaped. complementary metal-oxide semiconductor (CMOS). A popular type of electronic image sensor technology. compound lens. A lens assembly containing more than one lens element. concave. A lens surface that curves inward.

constant aperture zoom. A zoom lens with the same maximum aperture value across the focal-length range. consumer lens. A lens manufactured to emphasize the lowest possible retail cost while maintaining acceptable optical quality. contrast. The range in brightness between a bright area and a dark area of an image. converging lens. A lens that focuses light down to a point. convex. A lens surface that bulges outward. CPU. See central processing unit. crop sensor. A digital image sensor that’s smaller in area than a specific standardized size. Usually refers to sensors smaller than 35mm film frames (36 x 24 mm). cropping factor. The decrease in field of view caused by using a smaller image sensor size. It can be thought of as trimming off the edges of an image. cross-processing. Developing film using a chemical process not intended for it. For example, slide film in print chemistry. crown glass. Traditionally, glass containing potassium oxide, noted for its low dispersion properties. curvature of field. An aberration in which the plane of focus isn’t flat, but curved. As a result, focus errors occur away from the center of the image. daguerreotype. The first widely used form of chemical photography, developed in the 1830s by Louis Daguerre. Images were recorded to specially treated metal plates. deep. When referring to depth of field, much of the image is in focus. defishing. Using software to correct for the barrel distortion of a fisheye lens. depth of field (DOF). The amount of a scene that’s in sharp focus based on distance from the camera. Can be deep (lots in focus) or shallow/thin (little in focus). depth of field preview. A button or control which stops a lens down to the desired aperture, in order to preview final depth of field. depth of field scale. A small scale that is on a lens and indicates the depth of field for a given aperture range.

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GLOSSARY

diaphragm. An adjustable light-blocking mechanism inside a lens, usually constructed of flat movable blades. Analogous to the iris of the eye. The opening in the diaphragm is the lens aperture. diaphragm blade. A flat, moving segment of a diaphragm. Diaphragms are constructed from multiple identical blades (usually from 5 to 12) that move in or out simultaneously as the aperture is changed. diffraction. An optical phenomenon that causes light to bend around small openings. The principle is exploited by pinhole lenses and diffractive optics but also causes a decrease in optical performance as an aperture becomes smaller. diffractive optics. Optical technology that employs diffractive principles to alter light. A few lenses use diffractive optic elements. digital camera. An electronic computer that can capture, process, and record a two-dimensional image of a scene. digital mirrorless. A digital camera that lacks a mirror. Light enters the lens and directly strikes the image sensor. dispersion. An optical phenomenon whereby white light, passing through a prism or optical material, is split up into its constituent colors. The cause of rainbows and chromatic aberration. distance scale. A little chart or scale on a lens indicating the distance, usually in meters and feet, at which the camera is focused. diverging lens. A lens that spreads light outward, away from a central point. ED. Extra-low dispersion glass. See low dispersion. EF. Electrofocus. An autofocus lens designed for a Canon EOS camera; also the mount used by compatible lenses. EF-S. Electrofocus, short back focus. A variant of the EF lens mount used for subframe digital EOS cameras. electromagnetic radiation. A type of energy with very different physical properties according to energy level (wavelength). Visible light is one type of EM energy. Radio waves, infrared, and X-rays are just three other types. EMD. Electromagnetic diaphragm. An electrically controlled adjustable diaphragm mechanism. enlarger lens (EL). A lens designed for a photographic enlarger for optical prints. Normally has aperture control but no focus control. EOS (electro-optical system). A brand of film and digital SLRs produced by Canon.

EVIL. See electronic viewfinder with interchangeable lenses. electronic viewfinder with interchangeable lenses (EVIL). A type of digital camera. Not an SLR. EXIF. See exchangeable image file format. exchangeable image file format (EXIF). A computer standard defining a way whereby certain pieces of metadata (information about information) such as focal length, shutter speed, and aperture can be encoded within a digital photograph. exposure compensation. A method for increasing or decreasing the exposure settings from the camera’s metered estimate. f-stop. A numeric value describing the aperture size of a lens. fast lens. A lens with a relatively large maximum aperture and which therefore lets in a lot of light when wide open. field of view. The amount of a scene that can be recorded by the lens or by the lens and camera combination. film. A transparent flexible material coated with light-sensitive chemicals and used to record images. filter. An add-on optical accessory that attaches to the end of a lens and alters its optical behavior. fisheye lens. A wide-angle lens that does not attempt to record all straight lines as straight, and which produces images with a characteristic bulging look. fixed focus. A lens with permanently set focus and that cannot be adjusted. flare. Non-image-forming stray light passing through a lens, resulting in decrease in contrast or patches of white on the final image. flat field reproduction. Flat objects are recorded correctly in focus across the surface. flint glass. Optical glass of a high refractive index. floating elements. See close range correction. fluorite. Calcium fluorite. A synthetic crystal used in some lenses, mainly by Canon, because of its low dispersive properties. fly by wire. A metaphor drawn from the aviation industry. Refers to a user interface in which there is no mechanical linkage between the input device (for example, the autofocus ring on a lens) and the device being controlled

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GLOSSARY

(for example, an autofocus motor). Instead, the input device sends electrical instructions to a remote motor. focal length equivalence. An inaccurate but popular way of describing the cropping factor, which results in a change in field of view but not actual focal length. focal length. An optical property of a lens that determines its field of view. focal plane shutter. A shutter that’s located directly in front of the film or image sensor. focal plane. A flat plane onto which the lens projects an image to be recorded. Film or an image sensor should be located at this position. focus. A point on an image surface where rays of light converge. A photo is in focus when points across the image are brought into focus as closely possible, resulting in a sharp image. focus confirmation. A light or beep that confirms that focus has been successfully acquired. This may be in response to an autofocus operation or, on some cameras, after focusing manually. focus limiter. A switch on a lens that restricts autofocus movement to a certain limited-distance range. Useful for preventing the lens from “hunting” off toward infinity when only macro focus is required. Four Thirds. A digital sensor chip 17.3 x 13 mm in size. Also a digital camera standard based around such chips. full-frame fisheye. A fisheye lens that records 180 degrees across the diagonal of the film frame. full frame. Usually an image sensor that is the same size as a frame of 35mm film. full-time manual (FT-M). An autofocus lens that can be adjusted manually even when set to autofocus mode. Based around an ultrasonic motor. gel filter. A thin, flexible plastic filter. geometrical optics. A system of mathematical rules that predicts the behavior of optical lenses based on a theory of light rays. glass. Transparent material, usually made mostly from silica, that is used in the construction of camera lenses. Also slang for a camera lens. graduated neutral-density (GND) filter. A filter that’s darkened at one end and clear at the other. Used for darkening skies and so on. grain. The appearance of texture or of tiny dots making up the smallest visible component of film or a chemical photographic print.

handheld or handholding rule. When using a full-frame camera at ISO 100, the shutter speed should never be slower than the reciprocal of the focal length to assure sharpness. helical. A tubular lens component, with spiral internal grooves, that allows a group of elements to move closer to or further from the image plane to permit focus or zoom adjustment. hunting. An autofocus mechanism moving back and forth repeatedly in an attempt to lock on focus. Common in low-light situations or when only low-contrast subjects are available. hyperfocal distance. The distance that, when focused on by the lens, will yield acceptable focus on all objects out to infinity. image circle. Most lenses project circular images onto the surface of film or a sensor. Coverage of the image circle needs to be adequate to cover the entire film or sensor. image sensor. A light-sensitive electronic chip employed by a digital camera to record a scene. image stabilizing (IS). An electromechanical technology that compensates for camera motion relative to the subject, thereby reducing blurring. infinity. Photographically speaking, just a long way away (e.g., a mountain, a cloud, the moon) and not truly infinite distance. infinity focus. The ability of a camera and lens to focus to photographic infinity. infrared. From “below red.” Electromagnetic energy that can be focused by lenses and detected by some cameras and films but isn’t visible to the human eye. interchangeable lens. A lens assembly that can be swapped out for another, via a standard mount mechanism, so as to alter the optical abilities of a camera. internal focus. A lens that does not change physical length when focused. All moving parts are internal to the lens barrel. internal zoom. A lens that does not change in physical length when its focal length is changed. ISO. A digital camera setting or film type that determines the sensitivity of the film or sensor to light. Based on standards published by the International Organization for Standardization (ISO). (no, it isn’t IOS) kit lens. A low-cost consumer lens that is included in the box with a new camera.

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GLOSSARY

landscape. Orientation of a rectangular image, where the width of the display area is greater than the height. Ideally suited for photographs of landscapes. lens. An optical device that focuses light for image-recording purposes. lens adapter. A machined metal ring that allows a lens from one camera system to be attached to a camera of a different system. lens element. A single piece of shaped and polished transparent material that makes up a compound lens. lens group. A series of lens elements arranged together for optical design purposes. lens mount. A mechanical attachment that permits a lens to be fastened to a camera. lens movements. The ability to tilt and/or shift a lens relative to the camera body. light. A form of electromagnetic energy that can be detected by the human eye, film, and digital image sensors. light leak. A bright patch in an image, caused by non-image-forming light entering the camera through a hole or other imperfection in the camera body. Live View. A video preview, updated in real time, of the scene as recorded by a digital camera’s image sensor. lo-fi. Low fidelity. Deliberately using photographic tools of low optical quality to take certain types of images. long focus throw. Lens must be turned a fair distance around to change focus, making more precise focus possible, but also making autofocus slower. long. A lens with a long focal length. See telephoto. low dispersion. The ability of glass and other materials to pass light with a minimum of dispersion and therefore minimal chromatic aberration. macro. A type of photography, or photographic tool such as a lens, that records very small but non-microscopic objects. manual focus. Adjusting correct lens focus by hand and eye. manual lens. Usually a lens with manual focus and no autofocus capabilities. maximum aperture. The largest aperture setting to which a given lens can be set.

medium format. A film format, 6 cm wide, used today mostly on expensive professional cameras. megazoom. Colloquial expression for a lens with a very large focal length range. meniscus lens. A lens element that is concave on one side and convex on the other. meridional. A line that’s perpendicular to a sagittal/radial line. Also known as a tangential line, and analogous to the rim of a wheel. metering. The process of taking light-level readings to determine correct photographic exposure. micro focus adjustment. The ability of some digital cameras to support user-specified focus adjustment settings for different lenses. microprism. A series of tiny prisms built into a viewfinder screen as a manual-focus assist. MILC. See mirrorless interchangeable lens camera. mirrorless interchangeable lens camera (MILC). A type of digital camera. Not an SLR. mirror. A reflective or, in the case of cameras, partly reflective surface. SLR cameras employ mirrors to direct light to either the viewfinder or the imaging surface. modulation transfer function (MTF). A chart that describes certain aspects of the optical performance of a lens. motion blur. Loss of sharpness or definition in an image, caused by camera motion relative to the subject, vice versa, or both. multicoating. A lens coating consisting of multiple layers. neutral density (ND) filter. A gray filter that blocks a certain amount of light passing through, regardless of color. noise. Speckled dots appearing in a digital image, caused by amplifying image brightness. Common with low-light or high-ISO photography. normal lens. A lens that is neither wide nor long. optical image stabilizing. See image stabilizing. optical property. A description of a way in which an optical device or material can alter light.

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GLOSSARY

optics. The branch of physical science related to light. From a photographic perspective, this usually refers to geometric optics, and scientific models that treat light as rays of energy. optoelectronic. A device or system combining optical (light-based) and electronic (electrical) technologies. pancake. Lens, usually a standard or slightly wide prime, with a very thin, flat barrel. parfocal. A zoom lens that maintains correct focus even after changing focal length. pellicle. A semitransparent SLR mirror. Also incorrectly referred to as “translucent.” perspective correction (PC). Compensating for perspective in some way. Typically used to refer to a shift lens. perspective. The way in which three-dimensional scenes are recorded in a two-dimensional form. Dependent on distance between object and viewer. photograph. A two-dimensional image that records a three-dimensional scene. Recorded optically using a camera and lens. photography. The process of recording waves of (usually visible) light energy, using film or a digital image sensor, in order to create a two-dimensional image. pincushion distortion. A type of geometrical distortion in which squares or rectangles appear to be squashed inward, as though sucked in. pinhole. A photographic technique that uses a tiny circular hole in a surface instead of a lens. plane of focus. The plane at which light emerging from the back of the lens converges. In the case of most cameras and lenses, this is precisely coincident with the film or image sensor, though a tilt lens allows for the plane of focus to be tilted. plano-concave. Describes a lens element that is perfectly flat on one side and concave on the other. plano-convex. Describes a lens element that is perfectly flat on one side and convex on the other. PMO. Precision molded optics. polarizing filter, polarizer. A photographic filter that can block light in one axis of polarization.

portrait. In a general sense, any device, setting, or technique used to record images of a person’s face. Also, the orientation of a rectangular photograph where the narrow edge is horizontal. prime lens. Also fixed focal length lens. A lens with a focal length that is permanent and cannot be altered. prism. A block of optically transparent material with flat angled sides that permit internal reflection of light. SLRs often contain pentaprisms as part of the viewfinder assembly. professional lens. Describes a lens constructed to a high build quality and optical standard. Designed to meet the image quality and toughness requirements of professional use. prosumer. Portmanteau combining professional and consumer. See advanced amateur. protective filter. A clear glass filter that is used to protect the outermost lens element of a lens. push-pull. A zoom lens that is telescoped in or out like a trombone to change focal length. rangefinder. A camera, uncommon today, with one lens for the viewfinder and the other for picture taking. The viewfinder shows two images of the same scene, which must be lined up for correct focus. rear focus. A lens that does not change physical length when focused. All moving components are at the back of the lens. rectilinear. A lens that attempts to record all straight lines as straight, unlike a fisheye lens. reflex. An anachronistic term for reflective. refraction. An optical phenomenon whereby light can slow down as it passes from one transparent material to another. The physical basis of nearly all photographic lenses. refractive index. A numeric value describing the ability of optical material to bend light. It’s also a ratio measuring the speed of light passing through the material compared to the speed of light in a vacuum. register. Also flange focal distance. The distance between the lens mount and the imaging surface. retrofocus. A design for wide-angle lenses that permits them to clear the mirror assembly of an SLR. Also known as reverse telephoto.

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GLOSSARY

ring flash. A circular flash unit that fits around the end of a lens, often a macro lens. ring ultrasonic. An ultrasonic focus motor consisting of a pair of concentric metal rings that fit around the lens elements. sagittal. A line that radiates from the center of a lens or image and runs to the edge. Analogous to a spoke of a wheel. Also known as radial, and contrasts with meridional. sample variation. The simple fact that not every technological device will have precisely the same performance characteristics as another device of exactly the same type. saturation. The intensity of a color. screw mount. A type of lens mount with threads. The lens is attached to the camera and rotated around several times to screw it into place. Seidel aberrations. Five basic lens aberrations described, though not discovered, by Ludwig von Seidel in 1857. These are geometric distortion, spherical aberration, coma, astigmatism, and curvature of field. shallow. When referring to depth of field, a very limited range of focus. shift lens. A lens with a mechanism that allows the barrel to be moved from side to side so that the optical axis of the lens is no longer centered on the image sensor. The barrel remains perpendicular to the image surface. short focus throw. A focus ring that can only be rotated a relatively short distance around. Since a tiny movement of the ring results in a big change in focus, a short throw makes accurate manual focus challenging, but also makes autofocus faster. shutter. A mechanism that blocks light from entering a camera and can open briefly to determine a picture’s exposure. simple lens. A lens consisting of a single lens element, such as a magnifying glass. single lens reflex (SLR). A type of camera with a single taking lens. This lens sends light to either the viewfinder or the film/image sensor depending on the position of a mirror. slow lens. A lens with a relatively small maximum aperture and that therefore lets in little light when wide open. SLR. See single lens reflex.

spherical aberration. An aberration where rays of light entering a lens can focus correctly at the center of the image, but become out of focus toward the edges. Caused by the use of a spherical lens. spherical lens. A lens element (or sometimes by extension, an entire compound lens) that has a constant radius of curvature across its surface, as though it were cut from a perfect sphere. split circle. Also split image. A manual-focus assist aid which appears in the viewfinder as a circle divided into two halves. Adjusting focus causes a split image to line up. standard lens. See normal lens. step ring. A simple metal ring that is used to adapt a filter of one size to a lens filter mount of another. STM. Stepper motor (Canon) autofocus. STM lenses are slower than USM, but operate smoothly and almost silently. This makes them ideal for video shoots with continuous autofocus, particularly when live audio is recorded. They may support fly by wire manual control. stopped down. Referring to a lens diaphragm when set to the smallest aperture setting. subframe. An image sensor that’s smaller in area than a full-frame sensor. Typically this means smaller than a frame of 35mm film. super telephoto. A telephoto lens with a very large aperture and long focal length. supermacro. A macro lens capable of a great deal of magnification. Such a lens may not be capable of infinity focus, restricting its utility to macro work only. sweet spot. Either an aperture setting, midway along the range, that offers the best optical performance for a given lens or, in the case of a tilt lens, the movable zone of sharpest focus. T-stop. A numeric value describing the absolute amount of light passing through a lens. Seen mostly on cinematic lenses, not still photography lenses. taking lens. The lens that actually takes the shot; the lens that transmits light to the image sensor or film. Some cameras have secondary lenses used for the viewfinder. teleconverter. An optical accessory that fits between a lens and a camera and increases the focal length of the lens.

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GLOSSARY

telephoto. A lens with a long focal length that can record and magnify objects far away. test chart. A printed paper chart with a variety of patterns, pictures, or shapes. The chart is photographed in order to evaluate the performance of a lens. third party. A company that manufactures lenses or other products compatible with another company’s product line. tilt lens. A lens with a barrel that can be tilted so that it is no longer perpendicular to the image surface. tilt-shift lens. A lens capable of both tilting and shifting. See shift lens and tilt lens. toy lens. A low-quality all-plastic lens used in a cheap toy camera. translucent mirror. A technically inaccurate term for a semitransparent SLR mirror. two-touch. A zoom lens with a rotating ring used to alter focal length. ultra-low dispersion (UD). See low dispersion. ultrasonic. A nearly silent autofocus motor technology. USM. Ultrasonic motor. ultraviolet (UV). From “above violet.” Electromagnetic energy that can be recorded by certain types of films but is invisible to humans. universal screw mount. The M42 threaded lens mount system; very popular in the 1960s. UV filter. A lens filter that is capable of blocking the passage of ultraviolet energy but is transparent to visible light. variable aperture zoom. A zoom lens with different maximum aperture values across the focal length range. varifocal. A zoom lens that has to be refocused each time the focal length is changed. viewfinder screen. An etched plastic or ground glass screen upon which an optical image of the scene is projected. This screen is seen through the viewfinder assembly. viewfinder. An optical assembly that provides the photographer with a visual preview of what the finished photo will look like.

vignetting. Darkening around the edge of an image. Sometimes caused by physical barriers to light, sometimes caused by light falling off from the center of the image, and sometimes induced intentionally. visible light. Electromagnetic energy that can be detected by human eyes, usually in contrast to IR and UV energy. wavelength. A measure of the amount of energy carried by a beam of electromagnetic energy such as light. In the case of light, wavelength determines the color visible to humans. weather-sealed or weatherproof. Camera or lens with various kinds of seals to reduce the risk of penetration by water, dust, and so on. Not the same thing as waterproof. well damped. Describes a moving part, such as a focus or zoom ring, that is precisely engineered and lubricated with heavy grease to give it a smooth and high quality feel. wide-angle. A lens that has a short focal length and records a large (wide) area of a scene. wide open. Referring to a lens diaphragm set to the largest aperture setting. working distance. The physical distance between the end of a lens and the subject. Important when doing macro work. zoom creep. The phenomenon of a zoom lens changing focal length when tilted up or down because of gravity. zoom lens. A lens with an adjustable, typically user-adjustable, focal length. zooming in. A colloquial expression meaning to adjust (lengthen) the focal length of a zoom lens. zooming out. Reverse of zoom in: to decrease the focal length.

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IN DEX

Index

Symbols 1.5x crop 33, 35, 36 1.6x crop 33, 35, 36, 265 35mm film 5, 30, 91, 264, 269, 288 50mm lens 115, 157, 177, 257 A Abbe, Ernst 17 aberrations 38, 184, 189, 209, 255, 288 Abrams, J. J. 199 abrasion 71 abuse 71, 172 acutance 196 Adams, Ansel 89 Adaptall 274, 279 adapter ring 239 adjustable focal length 29 Adobe Photoshop 114, 188, 211, 213 advanced amateur 288 advanced amateur lens 73 aerial perspective 130 airplane 109 Alhambra 217 al-Haytham 11, 189 Alhazen. See al-Haytham aluminum 71, 138 anamorphic 288 anamorphic lens 199, 259 anamorphic lens flare 237, 259, 281 ancient Greece 10, 184 Angénieux 179 antireflective. See coating aperture 38, 44, 47, 62, 66, 82, 84, 144, 191, 221, 288 Aperture Indexing (AI) 242 Aperture Photographic 166 aperture priority 246 aperture ring 288 apochromatic (APO) 69, 187, 288 apodization 204 APS 34 APS-C 34, 108, 274, 288 architectural photography 127, 214 Arri PL 219, 264, 278 arsenic 182 Arts et Métiers metro station 187 aspherical 183, 288

aspheric lens element 190 Assyria. See Nimrud lens astigmatism 194, 288 astrophotography 66 auction sites 168 Austin Mini 27 Austria 14 autoexposure 245, 288 autofocus 55, 56, 66, 92, 94, 153, 157, 165, 217, 226, 233, 244, 265, 282, 288 axial chromatic aberration 186 B back focus distance 242, 265 background blur 85 Bacon, Roger 11 bag 160 bait and switch 169 bamboo forest 25 Barnack, Oskar 267 barrel distortion 113, 193, 195, 289 Barry Lyndon 43, 48 bayonet filter 139 bayonet lens mount 53, 289 bellows 157, 210, 289 between-the-lens 289 beyond economical repair (BER) 289 biconcave 180, 289 biconvex 180, 289 Big Rig Jig 100 bird Canada goose 24 great grey owl 102 king vulture 103 seagull 3 spectacled owl 280 bisected lens 22 black-and-white filter 147 block diagram 23, 29, 179, 289 Blodgett, Katherine 200 blur 58, 194 body 289 bokeh 44, 203, 220, 255, 257, 289 borosilicate glass 182 brassing 71, 289 breech lock lens mount 53, 265, 289 bridal veil 145 British Museum 10

build quality 70, 98, 165, 289 bulb blower 224 bull 121 Burning Man arts festival 100, 118, 121, 142, 175, 199, 223 C cadmium 182 camera 13, 14, 15, 35, 289 camera obscura 13, 14, 258 camera phone 252 camera store 166 Canada Surrey, British Columbia 78 Vancouver 32 White Rock 192 Canada Place 32 candles 4, 43 Canon 5, 6, 53, 57, 61, 73, 75, 98, 113, 152, 153, 157, 165, 173, 187, 207, 209, 215, 234, 244 16-35 2.8L lens 98 17-40 4L USM lens 68 24-70 2.8L lens 98 24-105 4L IS USM lens 29 28-80 2.8-4L USM lens 280 50mm 1.8 lens 29, 68 65mm MP-E lens 93 70-200 2.8L lens 69, 98, 99 70-200 4L lens 52 85mm 1.2L lens 41 85mm 1.8 lens 41 135mm 2.8 SF lens 191 400mm 2.8L lens 120 Cinema EOS 264 EF 38, 45, 73, 241, 242, 265, 278, 292 EF-S 33, 35, 38, 222, 265, 278, 292 EOS 33, 45, 54, 55, 56, 99, 252, 292 EOS 1D Mark IV 2, 98 EOS 5 5 EOS 5D Mark II 216 FD 264, 278 FL 264, 278 L 71, 73, 190 S-mount 50mm 0.95 lens 43 Subwavelength Structure Coating (SWC) 202 Carl Zeiss 17, 75, 200

Carl Zeiss Jena 239 catadioptric lens 204, 220, 289 cathedral 3, 32 CCD 15, 289 Chevalier, Vincent and Charles 16, 261 chip 15, 165, 244, 290 chromatic aberration 69, 155, 182, 185, 186, 220, 246, 288, 290, 292 cinematography 40, 43 circle of confusion (CoC) 207, 290 circular polarizer 144 cleaning lenses 224 clean, lubricate, and adjust (CLA) 226, 290 clear filter 30, 140 Close Encounters of the Third Kind 198 close focus distance 206, 290 close range correction (CRC) 290 closeup. See macro closeup filter 157 clutch focus 64, 290 CMOS 290 C-mount 264 coatings 141, 183, 198, 199, 200, 221, 290 Cokin 148 cold weather 79 color 185, 290 color-correction filter 146 colored ring 75 color filter 146 color fringing 185, 187 coma 194, 290 comic portraiture 108, 125 compatibility 165 complex distortion 193 compound lens 21, 177, 290 compressed perspective 118, 121, 130, 133 compromise 184, 193, 232 computational optics 17, 83 computer 17, 55 concave 290 concert photography 99 condensation 79 constant aperture zoom 41, 291 consumer lens 73, 179, 231, 291 Contax 266, 278 Contax-Yashica (CY) 266, 279 contrast 291 converging lens 180, 185, 291 converging verticals 127, 130, 213 convex 291 Cooke triplet 67 Cool Hand Luke 198 cooling filter 146, 148 corner sharpness 155

Cosina 68, 71, 250, 268 CPU 67, 290, 291 crabs 91 creative bokeh 257 cropping factor 31, 32, 33, 34, 252, 291 crop sensor 291 cross-processing 291 cross-section 23 cross sensor 55 crown glass 182, 291 CS-mount 264 curvature of field 92, 158, 195, 291 D Daguerre, Louis 14, 16, 291 daguerreotype 14, 291 dedicated hood 150 deep depth of field 47, 291 defishing 113, 291 depth of field (DOF) 38, 43, 46, 84, 206, 258, 280, 291 depth of field preview 45, 291 depth of field preview button 208 depth of field scale 66, 291 de Spinoza, Baruch 13 diagonal degrees of coverage 26 Diana 251, 252, 253 diaphragm 38, 39, 44, 45, 203, 292 diffraction 11, 44, 209, 292 diffraction filter 210 diffraction limit 209 diffractive optic lens 209, 292 digital 196 digital camera 5, 6, 15, 16, 31, 146, 202, 292 digital correction 188, 194 digital lens 221 digital SLR (DSLR) 15, 34, 89, 218, 265 diopter 157 dispersion 11, 185, 186, 292 distance scale 65, 92, 292 distortion 126, 127, 192, 251 diverging lens 180, 292 Doctorow, Cory 254 DOF preview 45 Dolby, Thomas 99, 217 double-Gaussian 17, 177 doublet 187, 189 dragonfly 103 drop-in filter 139 dust 141, 223, 225 DX. See Nikon DX dynamic range 145

E Earthshine 27 eclipse 14 eco glass 182 ED glass 187 Edinburgh’s Camera Obscura 228 EF-S. See Canon EF-S Eiffel Tower 112 electromagnetic diaphragm (EMD) 45, 292 electromagnetic radiation 12, 227, 292 electronics 52, 66, 67, 244 Emil Busch AG 259 engineering plastics 71 England Arundel 3, 49 Beer 3 Birmingham 164 Greenwich 107 Kew Gardens 26 London 79, 99, 110, 111, 127, 130, 132, 155, 166, 173, 214, 226, 280 Norwich 168 Old Warden Park 102, 280 enlarger lens (EL) 292 EVIL 293. See mirrorless EXIF (exchangeable image file format) 67, 82, 293 exposure 38, 66, 100 exposure compensation 293 exposure value (EV) 40 extender. See teleconverter extension tube 90, 91, 155, 206, 260 extramission theory 10 extreme wide angles 108 eye 38, 140 F fairy chimneys 32 fast lens 4, 42, 43, 44, 60, 89, 94, 100, 264, 280, 293 Ferrari 458 Italia 119 field of view 24, 26, 28, 212, 293 film 14, 30, 34, 38, 140, 146, 251, 293 filmmaking 40, 43, 108, 197, 217, 255, 259, 288 filter 136, 225, 293 filter diameter 137 filter height 138 filter holder 148 filter mount 138, 152, 154 filter reflections 142 filter thread 137, 157 filter wrench 137 firmware 165

305

IN DEX

306

IN DEX

fisheye 36, 109, 150, 154, 160, 164, 224, 241, 246, 293 circular 4, 36, 110, 112, 164, 197, 290 full-frame 36, 110, 111, 281, 294 zoom 113 fishing line 259 Fixation 173, 227 fixed focal length lens 28 fixed focus 54, 293 flag 197 flange focal distance 241 flash 89, 136 flat field reproduction 293. See curvature of field flint glass 182, 293 floating elements 290 flocking 152 flower icon 91 fluorescent 146 fluorite 77, 183, 187, 227, 293 fly by wire 280, 293 focal length 26, 28, 31, 33, 35, 39, 44, 58, 66, 82, 84, 92, 106, 152, 176, 203, 294 focal length equivalence 30, 33, 294 focal length multiplier 33 focal length range 29, 42, 82, 97, 122, 180 focal plane 176, 294 focal point 176 focus 46, 48, 62, 294 focus breathing 180, 219 focus confirmation 244, 294 focusing rails 159 focus limiter 92, 294 focus preset 64 focus pulling 217, 244 focus screens 247 focus test 282 follow-focus mechanism 218 Four Thirds 33, 54, 266, 278, 294 France 15 Cambieure 208 High Pyrenees 103 Paris 4, 27, 46, 112, 143, 151, 187, 224, 281 freelensing 258 f-stops 39, 219, 293 Fujifilm X-Pro1 6, 267 full-frame 34, 36, 38, 91, 108, 294 full-frame sensor 33 full-time manual (FT-M) 56, 57, 294 fungus 226 G Galen 10 Galilei, Galileo 13

Gaudí, Antoni 149 gel filter 139, 140, 294 geometrical optics 16, 294 Germany 17 Cologne 120 Duisburg 51, 253, 280 Essen 108 Oberhausen 81, 280 giant nose problem 108, 124, 125, 126 Gilliam, Terry 108 Giotto Rocket 225 glass 12, 13, 17, 21, 41, 46, 145, 186, 224, 294 cristallo 13 lead 13 glass of water 21 good copy 232 graduated neutral density (GND) 65, 145, 294 grain 294 gray market 171 great white 77 Greece Mykonos 146, 205, 248 Santorini 247 Gretzky, Walter and Wayne 96 grit 224, 225 ground aspheric lens 190 gyroscope 59 H halation 191 half-frame camera 31 Hall, Conrad 198 handheld rule 58, 124, 295 hanko 195 Hartblei Super-Rotator 216 Hasselblad 7, 34, 139, 173, 278 Hat Creek Radio Observatory 101 helical 62, 71, 259, 295 Helios 204, 269 high dynamic range (HDR) 87, 146 holding back 146 Holga 251, 252 homemade lens 259 horizontal degrees of coverage 26 Houses of Parliament 226 Hungary Budapest 101 hunting 64, 295 Huygens, Christiaan 12 hyperfocal distance 206, 295 hyperopia 180 HyperSonic Motor (HSM) 57, 69 hyperspace 63

I image area 26, 48 image circle 35, 212, 241, 265, 295 image sensor 15, 26, 31, 32, 33, 34, 38, 48, 84, 176, 201, 249, 295 image stabilizing 59, 66, 94, 295 impact 141, 227 infinity 26, 66, 177, 206, 208, 295 infinity focus 66, 92, 157, 180, 242, 246, 265, 295 infrared distance scale 229 infrared (IR) 199, 227, 295 infrared photography 65, 227 intentional flare 198 interchangeable lens 2, 3, 53, 77, 154, 238, 255, 295 interference 200 interior photography 214 internal focus 65, 295 internal zoom 65, 295 Internet 232, 261 Ireland Dublin 128 IS. See image stabilizing ISO 38, 58, 95, 99, 144, 295 Italy Florence 106 Murano 13 San Galgano 100, 114 San Gimignano 197 Siena 32, 105, 281 Venice 13, 117, 123 Vernazza, Cinque Terre 35, 36, 144, 228 Volterra 229 J Japan Futami, Mie 135, 281 Kyoto 131 Sagano Arashiyama 25 Tokyo 167, 195, 212 Wakayama Prefecture 86 Japan Camera Inspection Institute (JCCI) 68 jubo 120 K Kenko 152, 156 Kenyon 59 Kepler, Johannes 11 kids 89 Kinax II 15 Kingslake, Rudolf 111

kit lens 2, 76, 169, 295 Kodak 266 DCS (Digital Camera System) 15 HIE infrared film 229 Instamatic 110 266 Portrait Brownie No 2 camera 54 Vest Pocket Camera 260 Kubrick, Stanley 43, 48, 218 Kyocera 266 L L39 enlarger lens 268 L39/LTM 267, 278 ladybug 91 landscape 85, 140, 296 Landschaftspark Duisburg-Nord 253 large-format film 34, 210 lead crystal 182 Leica 61, 67, 72, 115, 250, 266, 267 M 268, 278 M9 6 Noctilux-M 50mm 0.95 ASPH 43 R 269, 278 Leitz, Ernst 267 lens 14, 21, 52, 296 lens adapter 252, 296 Lensbaby 253, 257 3G 255 Composer 251, 254 Edge 80 255 lens barrel 138, 177, 183, 188, 288 lens cap 14, 160 lens design 16, 184 lens designer 20, 23, 181 lens element 23, 29, 115, 142, 156, 176, 177, 178, 180, 184, 196, 199, 253, 296 lens flare 149, 152, 196, 198, 259, 293 lens focal length adapter 154 LensForge 17, 177 lens grinding 12, 17, 183, 190 lens groups 23, 296 lens hood 111, 149, 197 lens maker 187, 193, 230, 233 lens mechanisms 52 lens mount 53, 54, 158, 164, 239, 296 lens movements 210 Lenspen 225 lens register 241 Lensrentals.com 173 lens reviews 233 lens wrench 183 lentil 180 light 10, 21, 78, 296 light leak 296 light waves 17 lily 158

linear polarizer 144 line pairs 230 liquid damage 227 Live View 47, 79, 90, 197, 208, 249, 258, 296 lo-fi photography 250, 296 logarithmic 40 LOMO 251 Lomography 251 London Underground 155 long 296 long exposure 101, 107 long focus throw 92, 244 longitudinal chromatic aberration. See axial chromatic aberration long lens 25, 95, 178 Lord of the Flies 181 low dispersion 296 low-dispersion glass (LD) 187 low-light photography 4, 29, 38, 42, 99, 116, 247 M M39 268, 278 M42 239, 243, 260, 269, 278 macro 49, 65, 90, 91, 94, 155, 296 macro lens 196, 206 macro rails 159 magnesium fluoride 200 magnification 153 magnification ratio 65 magnifying glass 21, 78, 176 Mamiya 7, 34, 278 Manhattan 87, 118 manual focus 54, 85, 165, 238, 246, 252, 296 manual-focus lens 250, 296 manufacturing 183, 184 mathematics 16, 40 matte box 150 maximum aperture 41, 66, 69, 296 mechanical coupling 244 medium format (MF) 7, 34, 252, 297 MegaOIS 61 megazoom 122, 297 meniscus lens 16, 297 menu item 234, 245 meridional 195, 230, 297 metadata 260 metal 71, 150 metering 297 microfiber 225 micro focus adjustment 234, 297 Micro Four Thirds 33, 222, 264, 266, 269, 278 microlens 206

microprism 247, 297 microprism collar 248 microscope 13, 264 MILC 297. See mirrorless Millennium Bridge 132 millimeter 177 Minolta 55, 204, 269, 273, 278 mirror 5, 117, 221, 249, 297 mirror lens 204, 220 mirrorless camera 5, 55, 84, 89, 178, 264, 267 mirror lockup 79 mobile phone 16 model world 211 modulation transfer function (MTF) 196, 230, 297 Mojave Desert 88 molded aspheric lens 190 Mono Lake 107 motion blur 57, 297 MTF chart. See modulation transfer function (MTF) mug 168 multicoating 297. See lens coatings Musée des Arts et Métiers 14, 16, 109 myopia 180 N NASA 7, 43 Natural History Museum 111 nautilus 258 negative lens 180 negative meniscus 180 Netherlands Keukenhof gardens 46, 90 neutral color (NC) 141 neutral density (ND) filter 38, 144, 281, 297 Newton, Isaac 11, 59, 185, 220 Niépce, Nicéphore 14, 16, 261 night sky 66 Nikkor 68, 227, 268 Nikon 5, 6, 53, 55, 56, 57, 61, 74, 75, 90, 98, 99, 152, 153, 157, 173, 187, 204, 207, 215, 216, 218, 234, 239, 242, 245 1 33, 240 8mm fisheye lens 112 45mm pancake lens 30 50mm 1.4 lens 41 200mm f/2 lens 95 AF-S 17-35 2.8D IF-ED lens 99 AF-S 24-70 2.8G ED lens 99 AF-S 70-200 2.8 VR II lens 99 AF-S Nikkor 50mm 1.4 G lens 69 CX 33, 279 D3x 108

307

IN DEX

308

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D90 216 DX 33, 35, 222, 279 ED 71, 74 F 54, 239, 242, 252, 279 F3 15 FX 35 G 45, 243 IX 279 Nano Crystal Coat 202 Nimrud lens 10 noise 297 Non-CPU 245 normal lens 24, 297 O Olympus 5, 6, 57, 61, 173, 222, 266, 279 opening up 39 optical cement 23 optical flaws 184 optical glass 141, 181, 191 optical performance 76 optical property 20, 26, 181, 203, 297 Optical Stabilization (OS) 61 optics 16, 176, 185, 261, 298 optoelectronic 298 orbs 197 Original African Indianz 99 Ø symbol 137 P Palais Garnier 110 Panasonic 6, 61 Lumix 33 Panavision PV 219, 272 pancake lens 30, 298 panning 60, 95, 96 panorama 89 paparazzi 62 parfocal 179, 298 Peleng 246 pellicle 298 Pentax 5, 6, 7, 26, 27, 34, 53, 55, 56, 57, 61, 65, 75, 113, 115, 173, 225, 279 Auto 110 SLR 39, 272 DA 18-135 3.5-5.6 ED AL IF DC WR lens 69 K 54, 242, 272 KAF 243 Limited 72 Pentax Q 2 Q 33, 77, 272, 279 SMC 85mm 2.8 FA Soft lens 191 Spotmatic 269 Super Takumar 50mm 1.4 lens 70 perfect hood 151

perspective 124, 128, 133, 298 perspective correction lens 211, 213, 298 petal hood 151 Petzval, Josef 14, 83 Petzval lens 14, 17, 67, 83, 260 phase detection autofocus 55 Phase One 7, 34 photography 10, 298 photojournalism 84, 98 Photokina 120 photon 12, 17, 38 pictorialist 89 Pike Place Market 60 pincushion distortion 193, 298 pinhole 13, 14, 258, 298 plane of focus 298 plano-concave 180, 298 plano-convex 180, 298 plastic 71, 138, 145, 150, 183, 191, 252, 253 plastic lens 154 Plato 10 PMO 298 point and shoot 48, 76, 137, 154, 166 polarizer. See polarizing filter polarizing filter 65, 138, 142, 152, 201, 298 Polaroid 34 SX-70 55 portrait 299 portrait lens 25, 83, 84, 189 portraiture 83, 119 positive lens 180 positive meniscus 180 powered zoom 62 preview screen 15, 33, 249 prime lens 27, 28, 30, 41, 66, 84, 88, 198, 219, 299 printed circuit board (PCB) 67 prism 12, 185, 249, 299 professional lens 71, 72, 98, 150, 179, 231, 299 projector 35, 189, 232, 259, 288 prosumer 299 protective filter 141, 142, 299 push-pull lens 62, 299 Q Quantaray 165 quarter wave plate 144 R radial 300. See sagittal radioactive 70, 182 railroad track 192

rainbow 185, 186, 210 rangefinder 6, 178, 267, 299 reading stone 12 rear focus 65, 299 rear nodal point 176 rear principal point 176, 179 rebates 171 rectilinear 108, 113, 193, 299 reflection 143, 144, 196, 199, 201, 202, 214 reflex 299 refraction 11, 21, 299 refractive index 181, 182, 299 Regent Street 214 register 299 rental 95, 172 repairs 226, 282 replicated aspheric lens 191 resolution 196 retrofocus 108, 178, 179, 299 reversing ring 157 ring flash 92, 300 ring ultrasonic 57, 300 rising/falling 210 rocketship 14 Rodenstock 268 Rokkor 269 Rollei 34, 139 Routemaster double-decker bus 256 Rowell, Galen 89 Royal Albert Hall 110 Royal Society, London 11, 220 rubber hood 152 Ruhr Museum 108 S safety 78 sagittal 195, 230, 300 sample variation 173, 233, 300 Samsung 6, 76, 273, 279 NX 33 Samyang 165, 273 saturation 300 Schuiten, François 187 Scotland Edinburgh 228 scratches 223 scratch-resistant 202 screw mount lens mount 53, 300 Seidel aberrations 300 selective focus 46, 217 serial numbers 70 Series filter 139 SETI (Search for Extraterrestrial Intelligence) Institute 101 Shake Reduction (SR) 62

shallow depth of field 47, 89, 94, 159, 300 sharpness 196 shift lens 211, 212, 300 shim 249 short focus throw 300 Shunt Lounge and Theatre Company 99, 280 shutter 14, 38, 39, 178, 300 shutter, electronic 39 shutter, focal plane 39, 294 shutter speed 42, 58, 144 Sigma 57, 61, 74, 75, 164, 266, 273, 279 50mm 1.4 lens 42 200-500 f/2.8 lens 120 APO Macro 180mm 3.5 EX DG IF HSM lens 69 EX 69, 74 Silent Drive Motor (SDM) 57 Silent Wave Motor (SWM) 57 silica 181, 187, 226 silicone gasket 225 simple lens 21, 300 single-lens reflex (SLR) 5, 55, 179, 300 skylight filter 138, 140 slim profile filter 138 slow lens 42, 300 Smakula, Olexander 200 snail 156 soft focus 191, 192, 253, 258 software 144, 148, 252 Sony 5, 6, 53, 56, 57, 61, 75, 117, 152, 153, 173, 204, 250 Alpha 33, 35, 54, 241, 273, 279 G 75 NEX 273 Spain Barcelona 149 Granada 217 Ronda 281 Zaragoza 121, 186 spectrum 146 Speed Graphic 98 speed of light 21 sphere 189 spherical aberration 11, 189, 191, 301 spherical lens 189, 301 spider 90 Spielberg, Steven 198 split-circle viewfinder 247, 248, 301 spokes 194, 300 spoon 21 sports photography 77, 84, 94, 120 Spudz 225 stacking filters 138 standard lens 24, 27, 36, 41, 115, 301 star filter 136

stars 44, 209 star trails 101 Star Trek 199 Steady Shot Inside 62 step down ring 138 stepper motor (STM) 45, 56, 218, 301 step ring 138, 301 step up ring 138 STM. See stepper motor (STM) stop-down metering 243 stopping down 39, 47, 196, 301 stores 166 subframe 34, 38, 58, 84, 93, 108, 301 subframe sensor 31, 33 subject to camera distance 127 sugar ball 91 sun 78 supermacro 93, 301 Super Multicoating (SMC) 69 Super Sonic Motor (SSM) 57 Supersonic Wave Drive (SWD) 57 super telephoto 120, 301 supplementary lens 154 sweet spot 209, 255, 301 swirly bokeh 204, 264 T taking lens 301 Tamron 57, 61, 64, 68, 76, 152, 160, 165, 274, 279 tangential 297. See meridional Taylor, H. Dennis 200 telecentric 222 teleconverter 152, 301 telephoto 302 telephoto lens 3, 25, 27, 32, 37, 82, 84, 88, 117, 119, 132, 177 telescope 21, 28, 117, 182, 220 temple 51, 199 test chart 232, 234, 282, 302 Thames Barrier 107, 122 The Diving Bell and the Butterfly 255 thermal imaging 228 third party 64, 164, 165, 302 thorium 182 tilt 210 tilt lens 211, 254, 302 tilt-shift lens 128, 211, 215, 302 T-mount 279 Tokina 64, 92, 113, 165 torii arch 86, 131 Tour de France 96 toy camera 250, 252, 258 toy lens 155, 302 translucent 273, 302

transverse chromatic aberration (TCA) 186 travel photography 96 trilobite 93 tripod 60, 85, 95, 96, 100, 109, 120, 159, 161, 208, 282 tripod mount 161 Trojan Horse 142, 223 tromboning 223 T-stops 40, 219, 301 tulip 90 Tunisia 14 Dougga 35 Sidi Bouhel 103 Turkey Cappadocia 32, 87 two-touch zoom 62, 302 U Uffizi Gallery 106 ultra-low dispersion (UD) 302 ultrasonic focus motor 56, 89, 302 Ultrasonic Silent Drive (USD) 57 ultraviolet laser 23 ultraviolet (UV) 140, 227, 302 universal screw mount 269, 278, 302 USA Alabama Hills 207 Black Rock Desert, Nevada 51 Bodie, California 212 Death Valley National Park 27, 88, 103, 153 Hat Creek, California 101 Inyo, California 130 Lava Beds National Monument 281 Mojave Desert, California 88 Mono County, California 107 New York 87, 118 Reno 63 Seattle 60, 61 used lenses 171 user interface 62, 165 USM. See ultrasonic focus motor UV filter 140, 302 V vacuum 21 van Leeuwenhoek, Antoni 13 variable aperture zoom 41, 302 varifocal 179, 302 varmint 103 vertical degrees of coverage 26 Vibration Compensation (VC) 61 Vibration Reduction (VR) 61, 227 video 216, 218, 219

309

IN DEX

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video camera 59 vidicon tube 266 viewfinder 6, 33, 247, 282, 302 viewfinder screens 248, 302 vignetting 138, 148, 152, 205, 251, 303 visible light 303 Voigtländer 14, 17, 39, 68, 83, 268 von Seidel, Ludwig 194 W warming filter 146, 148 warranty 70, 170 water 143 Waterhouse stop 39 water lily 26 wavelength 303 weather-sealed 41, 72, 98, 141, 225, 303 well damped 303 Wex Photographic 168 white balance 146

white lens 77 wide-angle 3, 303 wide-angle distortion 127 wide-angle lens 25, 27, 32, 85, 88, 106, 132, 150 wide open 208, 209, 303 wildlife photography 102 window glass 181 Wood effect 228 Wood, R. W. 111, 228 working distance 303 Wratten 148 Y Yashica 266 Yodobashi Camera 167

Z Zabriskie Point 88 Zeiss 67, 71, 165, 218, 266 Biotar 204 Compact Prime CP.2 219 Contarex 22 Makro Planar 2/50 250 Planar 218 Planar 50mm 0.7 43 Tessar 67 Vario-Sonnar 22 Zeiss Optical Museum, Oberkochen 12, 13, 14, 22, 83, 200 Zenitar 246 zoom creep 303 zooming in 29, 303 zooming out 29, 303 zoom lens 22, 29, 30, 41, 62, 76, 96, 198, 303 zoom lock 62