Main Light Science & Magic: An Introduction to Photographic Lighting
Light Science & Magic: An Introduction to Photographic LightingFil Hunter, Steven Biver, Paul Fuqua
Фундаментальное, авторитетное изложение теории и практики света в фотографии. От общих установок до тонкостей и изысков (вроде «black-on-black»). Light Science and Magic provides you with a comprehensive theory of the nature and principles of light, with examples and instructions for practical application. Featuring photographs, diagrams, and step-by-step instructions, this book speaks to photographers of varying levels. It provides invaluable information on how to light the most difficult subjects, such as surfaces, metal, glass, liquids, extremes (black-on-black and white-on-white), and portraits.
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Light: Science & Magic Photographic lighting is a topic that will never go out of style, no matter how sophisticated cameras and other technology get. Even with the most high-tech gear, photographers still need to put a lot of thought and vision into lighting their photographs in order to get great results. This key skill has the power to dramatically and quickly improve photographs. Light: Science & Magic provides you with a comprehensive theory of the nature and principles of light, with examples and instructions for practical application. Featuring photographs, diagrams, and step-by-step instructions, this book speaks to photographers of varying levels. It provides invaluable information on how to light the most difficult subjects, such as surfaces, metal, glass, liquids, extremes (black-on-black and white-on-white), and portraits. This new edition includes: • • • • • All new chapter entitled “Setting Up Your First Studio” A re-vamped and expanded chapter 8, “Making Portraits” New appendix of reliable photo gear sources Over 100 new photographs and informational sidebars Updated information about advances in flash equipment, LED panels, and fluorescent lights Styles of lighting continue to change, but the nature of light will always remain the same. Once photographers understand the basic physics of lighting, they can apply that knowledge to a broad range of photographic styles. Fil Hunter was a highly respected commercial photographer specializing in still life and special effects photographs for advertising and editorial illustration. During a career spanning over three decades, he worked for such clients as America Online (AOL), US News, Time-Life Books, Life Magazine (27 covers), the National Science Foundation, and National Geographic. He taught photography at university level and served as technical consultant on a number of photographic publications. Mr. Hunter won the Virginia Professional Photographer’s Grand Photographic Award three times. Steven Biver has over twenty years of experience as a commercial photographer specializing in portraits, still life, photomontage, and digital manipulation. His client list includes Johnson & Johnson, USDA, William & Mary College, Condé Nast, and IBM. He has been honored with awards from Communication Arts, Graphis, HOW Magazine, and Adobe, who have also included his work on a Photoshop ‘extras’ disc to inspire other photographers. He is also the co-author of FACES: Photography and the Art of Portraiture, another Focal Press publication. Paul Fuqua has worked as an editorial and wildlife photographer for more than thirty-five years. He started his own production company in 1970 and is dedicated to teaching through the use of visuals. Paul has written and produced educational and training material in a variety of fields including law, public safety, history, science, and the environment. For the last ten years he has produced educational material dealing with the natural sciences and the need for global habitat stewardship. Paul is also a co-author of FACES: Photography and the Art of Portraiture for Focal Press. Light: Science & Magic An Introduction to Photographic Lighting Fifth Edition Fil Hunter Steven Biver Paul Fuqua iii First published 2015 by Focal Press 70 Blanchard Road, Suite 402, Burlington, MA 01803 and by Focal Press 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN Focal Press is an imprint of the Taylor & Francis Group, an informa business © 2015 Fil Hunter, Steven Biver, and Paul Fuqua The right of Fil Hunter, Steven Biver, and Paul Fuqua to be identified as authors of this work has been asserted by them in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging in Publication Data CIP data has been applied for ISBN: 978-0-415-71940-7 (pbk) ISBN: 978-0-415-71941-4 (hbk) ISBN: 978-1-315-86739-7 (ebk) Typeset in New Caledonia By Keystroke, Station Road, Codsall, Wolverhampton Dedication We dedicate this book to our friend and co-author, Fil Hunter. It is his pioneering vision that this book so largely reflects. Sadly, Fil died while this edition was in preparation after a long and tortuous battle against a terrible disease. We shall miss him, as will many others in the photography community. Steven Biver and Paul Fuqua --~ounaIro F Create You are a creator Whatever your form of expression - photography, filmmaking, animation, games, audio, media communication, web design, or theatre -you simply want t o create without limitation. Bound by nothing except your own creativity and determination. Focal Press can help. For over 75 years Focal has published books that support your creative goals. Our founder, Andor Kraszna-Krausz, established Focal in 1938 so you could have access t o leading-edge expert knowledge, techniques, and tools that allow you t o create without constraint. We strive t o create exceptional, engaging, and practical content that helps you master your passion. Focal Press and you Bound t o create. I We'd love t o hear h o w we've helped you create. Share your experience: www.focaIpress.com/boundtocreate Table of Contents Dedication Special Thanks Introduction v xvii 1 Chapter 1 Light: the Beginning Lighting Is the Language of Photography What Are the “Principles”? Why Are the Principles Important? How Did We Choose the Examples for This Book? To Do or Not to Do? What Kind of Camera Do I Need? A Word of Caution What Lighting Equipment Do I Need? What Else Do I Need to Know to Use This Book? What Is the “Magic” Part of This Book? 5 6 6 8 9 10 12 13 16 17 18 Chapter 2 Light: the Raw Material of Photography What is Light? How Photographers Describe Light Brightness Color Contrast “Light” Versus “Lighting” How the Subject Affects Lighting Transmission 21 22 26 27 27 29 33 36 36 vii TABLE OF CONTENTS “Direct” Versus “Diffuse” Transmission Absorption Reflection 39 40 41 Chapter 3 The Management of Reflection and the Family of Angles Types of Reflections Diffuse Reflections The Inverse Square Law Direct Reflections The Family of Angles Polarized Direct Reflection Is It Polarized Reflection or Ordinary Direct Reflection? Turning Ordinary Direct Reflection into Polarized Reflection Applying the Theory 43 44 45 49 50 54 55 60 62 63 Chapter 4 viii Surface Appearances Photographer as an Editor Capitalizing on Diffuse Reflections The Angle of Light The Success and Failure of the General Rule The Distance of Light Doing the Impossible Using Diffuse Reflection and Shadow to Reveal Texture Capitalizing on Direct Reflections 65 66 67 68 73 75 78 Complex Surfaces 89 83 85 TABLE OF CONTENTS Chapter 5 Revealing Shape and Contour Depth Clues Perspective Distortion Distortion as a Clue to Depth Manipulating Distortion Tonal Variation 95 97 98 99 100 102 The Size of the Light Large Lights Versus Small Lights Distance from the Subject The Direction of the Light Light on the Side Light above the Subject Fill Light Adding Depth to the Background How Much Tonal Variation is Ideal? Photographing Cylinders: Increasing Tonal Variation The Glossy Box Use a Dark- to Medium-toned Background Eliminate Direct Reflection from the Box Top Move the Light Source toward the Camera Raise or Lower the Camera Use Falloff Eliminate Direct Reflection from the Box’s Sides Put a Black Card on the Tabletop Tip the Box Use a Longer Lens 103 104 105 107 108 110 112 116 120 Finish with Other Resources Try a Polarizer 129 130 120 123 124 125 126 126 127 128 128 129 129 ix TABLE OF CONTENTS Use Dulling Spray Use Direct Reflection 131 131 Chapter 6 x Metal Flat Metal Bright or Dark? 133 134 136 Finding the Family of Angles Position a White Target Where You Think the Family of Angles Will Be Place a Test Light at the Camera Lens Aim the Test Light Study the Position and Shape of the Area Marked on the Test Surface Lighting the Metal Keeping the Metal Bright What Is a “Normal” Exposure for Metal? Keeping the Metal Dark The Elegant Compromise Controlling the Effective Size of the Light Keeping the Metal Square Use a View Camera or Perspective Control Lens Aim the Camera through a Hole in the Light Source Photograph the Metal at an Angle Retouch the Reflection Metal Boxes A Light Background A Transparent Background A Glossy Background 136 Round Metal 169 137 137 138 139 140 140 144 145 149 152 157 157 158 160 160 160 163 164 167 TABLE OF CONTENTS Camouflage Keeping the Light Off the Camera Using a Tent Other Resources Polarizing Filters Black Magic Dulling Spray Where Else Do These Techniques Apply? 171 171 172 174 175 175 176 176 Chapter 7 The Case of the Disappearing Glass Principles Problems Solutions Two Attractive Opposites Bright-field Lighting Choose the Background Position the Light Position the Camera Position the Subject and Focus the Camera Shoot the Picture Dark-field Lighting Set Up a Large Light Source Set Up a Dark Background Smaller Than the Light Source Position the Camera Position the Subject and Focus the Camera Shoot the Picture The Best of Both Worlds Some Finishing Touches Defining the Surface of Glassware 179 179 180 180 182 182 184 184 185 186 186 188 189 190 191 192 192 193 194 195 xi TABLE OF CONTENTS Illuminating the Background Minimizing the Horizon Stopping Flare Eliminating Extraneous Reflections Complications from Nonglass Subjects Liquids in Glass Liquid as a Lens 199 200 203 204 205 205 206 Keeping True Color Secondary Opaque Subjects Recognizing the Principal Subject 208 211 212 Chapter 8 xii Making Portraits The Single-light Portrait Set-up The Basic Set-up Light Size Skin Texture Where to Put the Main Light The Key Triangle Key Triangle Too Large: Main Light Too Near the Camera Key Triangle Too Low: Main Light Too High Key Triangle Too Narrow: Main Light Too Far to Side Left Side? Right Side? Broad Lighting or Short Lighting? Eyeglasses Additional Lights Fill Lights Reflector Cards as Fill Lights 215 216 216 218 219 220 221 Background Lights 234 222 223 224 225 225 227 228 229 232 TABLE OF CONTENTS Hair Lights Kickers Rim Lights Mood and Key Low-key Lighting High-key Lighting Staying in Key 236 238 241 242 243 244 247 Dark Skin The Unfocused Spot Using Colored Gels 247 249 254 Chapter 9 The Extremes The Characteristic Curve The Perfect “Curve” A “Bad” Camera Overexposure Underexposure Using Every Resource White-on-White Exposing White-on-White Scenes Lighting White-on-White Scenes Subject and Background Using an Opaque White Background Light the Subject from Above Use a Gobo Above the Subject Add Dimension Using a Translucent White Background Using a Mirror Background In Any Case, Keep the Background Small 257 258 258 261 263 265 270 270 271 274 275 276 277 278 281 282 286 287 Black-on-Black 288 xiii TABLE OF CONTENTS Exposing Black-on-Black Scenes Lighting Black-on-Black Scenes Subject and Background Using an Opaque Black Background Using a Glossy Black Surface Keeping the Subject Away from the Background 289 290 291 293 296 Histograms Preventing Problems Overmanipulation Curves New Principles 299 301 303 305 306 297 Chapter 10 xiv Traveling Light The Lights We Use Heavy-duty Portable Strobes “Hot-shoe” Flashes LED Panels Getting the Exposure Right Letting Your Flash Do the Figuring Using a Meter Meters and LEDs Getting More Light Multiple, or “Ganged”, Flashes Battery Packs Flash Extenders Getting Better-quality Light The Problems Take It Off 309 310 310 311 312 313 314 314 315 315 316 318 318 319 319 320 Bouncing From Hard To Soft 321 TABLE OF CONTENTS The Omni-Bounce—A Big Help For a Little Money “Raccoon Eyes” Feathering Your Light Forcing the Shadow Lights of Different Colors Why Is the Color of the Light Important? Tungsten Daylight Nonstandard Light Sources Do the Colors Mix? The Remedies Correcting Mixed Colors Correcting Unmixed Colors Filtering Daylight Correcting Errors in Reproduction Lights of Different Duration Different Approaches Other Useful Gear 323 324 326 328 329 330 330 331 331 334 337 337 338 339 340 340 342 348 Chapter 11 Setting Up Your First Studio Lights: An Early Issue Getting Your Lights Right What Kind of Lights? Flash Continuous Lights How Many Lights? Light Stands Booms Light Modifiers—Which Do I Need? 353 354 356 356 357 358 359 359 361 361 xv TABLE OF CONTENTS Diffusers Reflectors Snoots and Grids Gobos and Flags Backgrounds Computers and Associated Gear Miscellaneous Equipment 362 363 364 364 365 366 367 What Sort of Space? 368 Appendix: Reliable Suppliers Index xvi 372 374 Special Thanks I would like to thank, Leah Bassett (Hair & Make-up), Nicolette Steele, Brynn Tucker, Mike Jones, Tessa Biver, Mark Romanoff, Mike Harvey, Jade Biver, Nigel Biver, Union 206 Studio, the late Vance Bockis, Adonis, Quiterio, and the folks at Focal Press. I would also like to thank my wonderful family for all their support. Steven Biver With gratitude and undying admiration for Robert Yarbrough— a teacher who taught. Paul Fuqua xvii 7KLVSDJHLQWHQWLRQDOO\OHIWEODQN Introduction Lighting is at the very heart of photography. Unlike some of our picture-making colleagues, we will not go quite so far as to claim that “Without great lighting, there can be no great photographs.” However, we do believe that comes close to being the truth. And that is exactly why we wrote the first edition of this book. In it we wanted to present a number of key lighting concepts in a clear, readily understandable way. Our aim remains exactly the same for this—the fifth edition. It is important to understand that this is not a “how to” book in the sense that the term is generally used. In it we rarely, if ever, suggest appropriate lens apertures, shutter speeds, flash settings, or other such information—information that is often an important part of the currently popular “recipe” approach to teaching lighting. If that is what you are looking for, you must look elsewhere. (Personally, we would recommend the brilliantly done “Digital Photography Book” series by Scott Kelby.) If, on the other hand, you want to understand something about the underlying nature of light and learn how to employ its key characteristics to the lighting of any sort of subject in any location or circumstance, we suggest that this is the right book for you. In it we present an overarching approach to photographic lighting. Applying it will enable you to understand why a subject looks the way it does when it is illuminated by any given “light,” and how to use this understanding to make exactly the picture you are after. 1 INTRODUCTION We also include chapters dealing with the peculiarities associated with using hot-shoe and similar flashes, and suggestions for those of you who may be considering setting up your first studio. Finally, in a brief appendix, we list some of the photographic suppliers from whom we have received particularly good services over the years. 2 7KLVSDJHLQWHQWLRQDOO\OHIWEODQN 4 1 Light: the Beginning Light: Science & Magic is a discussion, not a lecture. You bring to this discussion your own opinions about art, beauty, and aesthetics. We do not intend to change those opinions and may not even influence them very much. We will be more annoyed than flattered if reading this book causes you to make pictures that do nothing but mirror ours. For better or worse, you have to build your own pictures on your own vision. What we do have to offer you is a set of tools. This book is about technology. Science. Brass tacks. It is information for you to use when you please, if you please, and how you please. This does not, however, mean that this book is not also about ideas, because it is. The basic tools of lighting are principles, not hardware. Shakespeare’s tool was the Elizabethan English language, not the quill pen he used. A photographer without mastery of lighting is like a Shakespeare who could speak only the language of the people in the Globe Theatre pit. Being Shakespeare, he still might have come up with a decent play, but it certainly would have taken a lot more work and, very likely, more blind luck than most people are entitled to expect. 5 LIGHT: THE BEGINNING LIGHTING IS THE LANGUAGE OF PHOTOGRAPHY Patterns of light convey information just as surely as do spoken words. The information that light conveys is clear and specific. It includes definite statements, such as “The bark of this tree is rough” or “This utensil is made of stainless steel, but that one is sterling.” Lighting, like any other language, has a grammar and a vocabulary. Good photographers need to learn both. Fortunately, photographic lighting is a lot easier to master than a foreign language. This is because physics, not social whim, dictates its rules. The tools we have included in this book are the grammar and vocabulary of light. Whatever we say about specific technique is important only to the extent that it proves the principles. Please, do not memorize the lighting diagrams in this book. It is entirely possible to put a light in exactly the same spot as shown in one of the diagrams and still make a bad picture—especially if the subject is not identical to that in the diagram. But if you learn the principles, you may well see several other good ways to light the same subject that we never mention, and which perhaps have never even occurred to us. WHAT ARE THE “PRINCIPLES”? 6 To photographers, the important principles of light are those that predict how it will behave. Some of these principles are especially powerful. You will, however, probably be surprised to find how few they are, how simple they are to learn, and how much they explain. We discuss these key principles in detail in Chapters 2 and 3. They are the tools we use for everything else. Then in later LIGHT: THE BEGINNING Working with Light Figures 1.1 These four images—very different pictures—are a small sample of some of the many different ways photographers have worked with light, be it either in a studio or the outside world. Credit: Steven Biver Credit: Steven Biver Credit: Mark Romanoff 1.1 Credit: Paul Fuqua Some examples of the different photographers that have worked with light. chapters we put them to work lighting a wide range of subjects. At this point we will simply list them: 1. The effective size of the light source is the single most important decision in lighting a photograph. It determines what types of shadows are produced and may also affect the type of reflection. 7 LIGHT: THE BEGINNING 2. Three types of reflections are possible from any surface: direct reflection, diffuse reflection, and polarized direct reflection. They determine why any surface looks the way it does. 3. Some of these reflections occur only if light strikes the surface from within a limited family of angles. After we decide what type of reflection is important, the family of angles determines where the light should or should not be. Just think about that for a minute. If you think lighting is an art, you’re exactly right—but it’s also a technology that even a bad artist can learn to do well. These are the most important concepts in this book. If you pay close attention to them whenever they come up, you will find they will usually account for any other details you may overlook or we forget to mention. WHY ARE THE PRINCIPLES IMPORTANT? The three principles we have just given are statements of physical laws that have not changed since the universe began. They have nothing to do with style, taste, or fad. The timelessness of these principles is exactly what makes them so useful. Consider, for example, how they apply to portrait style. A representative 1952 portrait does not look like most portraits made in 1852 or 2014. However, and this is the important point, a photographer who understands light could duplicate either of them. Chapter 8 presents a number of useful approaches to lighting a portrait. But some photographers will not want to adopt those approaches, and even fewer will do so in 20 years. We do not care whether or not you use the methods of portrait lighting we chose to demonstrate. 8 LIGHT: THE BEGINNING We do, however, care very much that you understand exactly how and why we did what we did. It is the answers to those very “hows” and “whys” that will allow you to produce your own pictures your own way. Good tools do not limit creative freedom. They make it possible. Good photographs take planning, and lighting is an essential part of that planning. For this reason, the most important part of good lighting happens before we turn on the first lights. This planning can take many days or it can happen a fraction of a second before pressing the shutter release. It does not matter when you plan or how long it takes, as long as you get the planning done. The more you accomplish with your head, the less work you have to do with your hands. Understanding the principles we presented above enables us to decide what lights need to be where before we begin to place them. This is the important part. The rest is just fine-tuning. HOW DID WE CHOOSE THE EXAMPLES FOR THIS BOOK? The portrait is but one of the several basic photographic subjects we discuss. We chose each to prove something about the basic principles. We also lit the subject to show the principle, regardless of whether there might be other good ways to light the same thing. If you master the principles, you will discover the other ways without any help from us. The above means that you should give at least some attention to every representative subject. Even if you have no interest in a particular subject, it probably relates to something you do want to photograph. 9 LIGHT: THE BEGINNING We also chose some of the subjects because they are rumored to be difficult. Such rumors are spread usually by people who lack the conceptual tools needed to deal with such subjects. This book dispels the rumors by giving you those tools. In addition, we tried to use studio examples whenever possible. This, however, does not mean Light: Science & Magic is only about studio lighting. Far from it! Light behaves the same way everywhere, whether it is controlled by the photographer, by the building designer, or by nature. But you can set up indoor experiments like ours at any hour of any day regardless of the weather. Later, when you use the same lighting in a landscape, on a public building, or at a press conference, you will recognize it because you will have seen it before. Finally, we chose each example to be as simple as possible. If you are learning photography, you will not have to leave the set-up in your living room or in your employer’s studio for days at a time to master it. If you teach photography, you will find that you can do any of these demonstrations in a single class session. TO DO OR NOT TO DO? If you are learning photography without any formal instruction, we suggest you try all of the basic examples in this book. Do not simply read about them. What happens in your head is the most important part of lighting, but the eye and the hand are still essential. Guided experience coordinates the three. When we talk about soft shadows or polarized direct reflections, for example, you already know how they look. They happen in the world, and you see them every day. But you will know them and see them still better once you have made them happen. 10 LIGHT: THE BEGINNING If you are a student, your class assignments will keep you busy enough without any further demands from us. Your teacher may use the exercises here or invent new ones. Either way, you will learn the principles in the book because they are basic. They happen in all lighting situations. If you are a professional photographer trying to expand your expertise, your judgment about what exercises you need is better than ours. Generally, these will be those that are least like the things you are already photographing. You may find our basic examples too simple to be an entertaining challenge. Try complicating things a bit. Add an unexpected prop, an unusual viewpoint, or a special effect to our basic example. You might as well get a striking portfolio piece out of the effort while you are at it. If you are a teacher, you can look at this book and see that most of the exercises show at least one good, simple, easyto-master way to light even those subjects with reputations for maximum difficulty: metal, glass, white-on-white, and black-onblack. Notice, however, that although we’ve done this in almost every case, we weren’t able to do it in absolutely every one of them. The “invisible light” exercise in Chapter 6, for example, is pretty difficult for most beginners. Some students may also find the secondary background behind the glass of liquid in Chapter 7 to be beyond the limit of their patience. For this reason, if you find anything in this book that you haven’t already done with your own hands and eyes, we strongly encourage you to try it yourself before deciding whether it is appropriate to the skills of your students. 11 LIGHT: THE BEGINNING WHAT KIND OF CAMERA DO I NEED? Asking “What kind of camera do I need?” may seem silly to experienced photographers. But we have taught this material. We know how many students ask it, and we have to answer it. There are two good answers, and they contradict each other slightly. The weight we place on each answer matters more than the answers themselves. Successful photographs depend on the photographer more than the equipment. Inexperienced photographers work best with the camera with which they are familiar. Experienced photographers work best with the camera they like. These human factors sometimes have more to do with the success of a photograph than purely technical principles. Ideally, people learning photography should shoot digitally for the instant feedback this approach provides. Shooting digitally is also far less expensive, and the quality that most of today’s digital cameras provide borders on amazing. Of the many photographs in this book, we made all but a handful digitally. Just which digital camera you should get is up to you. Fortunately, most manufacturers offer a number of reasonably priced models. Check out the many reviews that you will find in photography magazines and on the web. Talk to other photographers and, if possible, deal with a camera store whose sales staff know what they are talking about. Camera clubs are also another good source of information, and, if you are in school, your instructor will also be able to help you select the camera that best fits your needs and budget. 12 LIGHT: THE BEGINNING A WORD OF CAUTION Any way you look at it, the advent of the digital world has been a wonderful thing for students. It has not, however, resulted in a totally win–win situation. Digital cameras are, at their hearts, computers. Because of this, camera makers can program the camera to alter the image they take without the foreknowledge or consent of the photographer! This is often a good thing. The camera’s decisions are, in our experience, more often than not correct. Sometimes, however, they are not. A still bigger problem is that it is hard for students to know whether what has happened, for better and for worse, is because of the camera’s decision or because of the photographer’s decision. You may make mistakes that the camera fixes, costing you a learning experience, or the camera can make a mistake and you innocently blame yourself for it. In light of the preceding paragraphs, we offer the following suggestions: 1. Develop at least a minimal competence in postproduction skills. You do not have to be a whiz-bang Photoshop genius to be an effective digital shooter. You do, however, need to learn at least the basics of one of the numerous (and often amazingly inexpensive) digital editing programs now available. 2. Shoot in the “Manual” mode. This will prevent your camera from “helping” you to get a technically satisfactory shot. It will, however, go a long way in that direction by leaving most of the decision making up to you and not your camera’s computer “brain.” 3. Shoot in the Raw format. Because of its minimal in-camera compression, it stores far more of the visual information that reaches your camera’s sensor than does the alternate JPEG format. 13 LIGHT: THE BEGINNING Thus, during postproduction when you are fine-tuning your images, your software has far more digital information with which to work. And this can make a big difference—a very big difference. A Raw Advantage We shot Figure 1.2 in the Raw format. While adequate, we feel that it lacks the tonal range and color, in other words the “snap,” needed for visual impact. 1.2 Farm boy from the Dominican Republic as shot in the Raw format before any postprocessing. 1.3 14 The same image as Figure 1.2, but after we did some postprocessing on it. LIGHT: THE BEGINNING Figure 1.3, by comparison, shows our young friend after we did some work on his image during postproduction. Because we shot the original in Raw, we had the flexibility we needed to produce the color and contrast treatment we wanted. Figure 1.4 is a monotone variation on the above theme. 1.4 Here we see a variation on the previous theme. Once again, it was our use of the Raw format that gave us the flexibility needed to produce this black and white image. Unfortunately, this book does not have the space needed to deal with the above three issues in detail. The “A Raw Advantage” box is but a quick look at some of the things you can do when shooting in Raw. For more complete information, please consult one of the many fine books on the subject available today. If you are a student, the remedy for this is a close, ongoing talk with your instructor about what’s happening in your pictures. If you are an experienced photographer, you can already tell when the camera is helping you and when it is hurting you. The hardest path is that of a novice photographer attempting to learn the material in this book without the benefit of formal 15 LIGHT: THE BEGINNING instruction. What we can offer all photographers is the assurance that the material we present in the following pages can, indeed, be learned in that very way. All three of the authors of this book did so. Talk with other photographers as much as possible. Ask questions, and always share with others whatever you have learned. WHAT LIGHTING EQUIPMENT DO I NEED? We expect you to ask this question, and we offer this two-part answer: 1. No photographer has enough lighting equipment to do every assignment as well as possible. No matter how much lighting equipment you have, there will be times when you want more. Suppose, for example, you can illuminate a large set to shoot at f/96 at 1/5000 a second. (Please call the fire department before turning on this apparatus.) You will probably then find that you want still more light in a particular shadow, or you may find that you need to light a yet larger area to fit the required composition. 2. Most photographers have enough equipment to do almost every assignment well. Even if you have no lighting equipment at all, you may be able to get the job done. Can the subject be photographed outdoors? If not, sunlight through a window may be a good light source. Inexpensive tools, such as white cloth, black paper, foam board, black gaffer tape, and aluminum foil, can allow you to control sunlight as effectively as the best manufactured equipment. 16 The above said, there is no dispute that good lighting equipment can be a great convenience. If the sun moves too far across the LIGHT: THE BEGINNING sky before you are ready to expose, you may have to wait until it returns the next day and hope there is no more and no less cloud cover the second time around. Professional photographers know that convenience becomes necessity when they have to photograph what the client wants when the client wants. This message is not aimed at professionals, however. They already know how to do whatever is needed with whatever is available. We are more interested in encouraging students now. You have advantages that professionals do not. Within broad limits, you can select the size of your subject. Small scenes require less light. You may not have a 3-by-4-foot soft box, but a desk lamp with a 60-watt bulb and a tracing paper diffuser can light a small subject nearly as well. Lack of equipment is, no doubt, a handicap. You know it and we know it. But it is not necessarily an insurmountable obstacle. A good dose of creativity may well overcome it. Just remember that creative lighting is the result of planning the lighting. Part of that creativity means anticipating the limitations you face and deciding how best to work within them. WHAT ELSE DO I NEED TO KNOW TO USE THIS BOOK? We assume you know basic photography. You know how to determine a reasonable exposure, at least close enough that bracketing can cover errors. You understand depth of field. You have mastered the basic operation of your camera. That is all. We have no intention of being ruthless in our examination of your background credentials. Just to be safe, however, we suggest you keep a good basic photography book on hand as you read this one. (We did when we wrote it.) We do not 17 LIGHT: THE BEGINNING want you to find easy material difficult just because we unknowingly use a technical term you have not seen before. Finally, do not overlook the Internet. There is a wealth of information to be found there about lighting and photography in general. A search here and a search there are moments well spent by any photographer—advanced or beginner. WHAT IS THE “MAGIC” PART OF THIS BOOK? Learn about the light and the science. Then the magic happens! 18 7KLVSDJHLQWHQWLRQDOO\OHIWEODQN 20 2 Light: the Raw Material of Photography In some ways, photographers resemble musicians more than painters, sculptors, and other visual artists. This is because photographers, like musicians, are more interested in the manipulation of energy than that of matter. Photography begins the moment light is emitted from a source. It climaxes with still more light reflected from a printed page or beaming from a monitor and striking a human eye. All steps in between involve the manipulation of light—whether to control it, to record it, or, ultimately, to present it to a viewer. Photography, at its heart, is the manipulation of light. Whether those manipulations serve artistic or technical purposes hardly matters; the two are often synonymous. Whether the manipulations are physical, chemical, electrical, or electronic, they are all motivated by the same mission and guided by the same understanding of how light behaves. In this chapter we are going to talk about light, the raw material from which we make pictures. You are already familiar with most of the ideas we will discuss. This is because you have been 21 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY learning to see since the day you were born. Even if you happen to be a novice photographer, your brain has already absorbed enough information about the behavior of light for you to be a master. Throughout this chapter we aim to attach words and labels to some of this unconscious and semiconscious information. This will make it easier for you to talk about light with other photographers, just as musicians find it easier to say “b flat” or “4/4 time” instead of humming a scale or tapping a rhythm. This is the most theoretical chapter in this book. It is also the most important because it is the foundation for all that follows. WHAT IS LIGHT? A complete definition of the nature of light is complex. In fact, several Nobel Prizes have been awarded for various contributions to the working definition we use today. We will simplify our discussion by using a definition adequate for applied photography. If you are still curious after reading this, see any basic physics text. Light is a type of energy called electromagnetic radiation. Electromagnetic radiation travels through space in tiny “bundles” called photons. A photon is pure energy and has no mass when at rest. A box of photons the size of an elephant weighs nothing. The energy of the photon produces an electromagnetic field around the photon. A field is invisible and cannot be detected unless there is a material object in the field on which it can exert a force. All this sounds pretty mysterious until one realizes that one common example of a field is the magnetic field surrounding an ordinary magnet. We cannot tell the field exists unless we 22 move a nail close enough for the magnet to attract it. Then the effect of the field is apparent: the nail jumps to the magnet. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY Unlike the field around the magnet, however, the electromagnetic field around the photon is not constant in strength. Instead, it fluctuates as the photon travels. If we could see this change in the strength of the field it would look something like Figure 2.1. Notice that the strength of the field moves from zero to its maximum-positive strength and then back to zero; it then repeats the pattern in the negative direction. This is why the field around a beam of light does not attract metal like an iron magnet does. The field around a photon of light is positive half of the time and negative the rest of the time. Thus the average charge of the two states is zero. As the term implies, an “electromagnetic field” has both an electrical component and a magnetic one. Each component has the same pattern of fluctuation: zero to positive, to zero, to Zero Field Strength Zero Field Strength Zero Field Strength '1 Maximum-negative Field Strength 2.1 The magnetic field around a photon fluctuates from its maximum-positive to its maximum-negative strength as the photon travels. The electrical field behaves exactly the same but out of phase with the magnetic field; whenever one field is at its maximum, the other is at its minimum strength. 23 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY negative, and back to zero again. The electrical component is perpendicular to the magnetic one. The relationship between these two components is easier to see if we assume that Figure 2.1 represents just the magnetic component. Then, if you turn this book so that the edge of the page is toward you, the same diagram will represent the electrical field. Whenever the strength of either the magnetic or the electrical component is at its maximum, the other is at its minimum, so the total field strength remains constant. All photons travel through space at the same speed, but the electromagnetic fields of some photons fluctuate faster than those of others. The more energy a photon has, the faster the fluctuation. Human eyes can see the effect of this difference in photon energy levels and in the rate of field fluctuation. Frequency • Frequency Frequency of Red Frequency of Light Red of Red Light of Light Red Light • Frequency Frequency of Blue of Light .s::::. "5 c ~ en "0 <ii u:: ti3 c..> "C t3Q) W ct: 0 0 c..> ~ c OJ C\l ~ Frequency Frequency of Red of Light Red Light 2.2 24 The rate at which the electromagnetic field fluctuates varies. We perceive this variation as different colors. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY We call the effect color (Figure 2.2). Red light, for example, has less energy than blue light, so the rate of its electromagnetic field fluctuation is only about two-thirds as fast. We call the rate of fluctuation of the electromagnetic field its frequency, and we measure it with the unit called Hertz, or, for convenience, megahertz (1 megahertz = 1,000,000 Hertz). Frequency is the number of complete wavelengths that pass a point in space each second. Visible light is only one narrow range out of all the many possible electromagnetic frequencies. Electromagnetic radiation can travel through a vacuum and through some forms of matter. We know that light, for example, can pass through transparent glass. Electromagnetic radiation is not closely related to mechanically transmitted energy, such as sound or heat, which can travel only through matter. (Infrared radiation and heat are often confused because they tend to accompany one another.) Sunlight Visible \ \ \ X-ray Ultraviolet / , I / I' Infrared '\ T T 1 2.3 1 1,000 million MHz 1,000,000 million MHz Radar Radio Radar T Radio This diagram shows the electromagnetic spectrum. Notice that visible light is but one small part of it. 25 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY reaches Earth, and very much beyond, without any fiber-optic lines to get it here. Modern cameras are sensitive to a far wider range of electromagnetic frequencies than the human eye can perceive (Figure 2.3). This is why a picture can be degraded by ultraviolet light, which we cannot see in a landscape, and film can be degraded by X-rays, which we cannot see emitted by a machine at an airport. HOW PHOTOGRAPHERS DESCRIBE LIGHT Even if we confine our attention to the visible portion of the electromagnetic spectrum, everyone knows that the effect of one group of photons may be radically different from that of another. Examining our album of mental images, we all see the difference between an autumn sunset, a welder’s arc, and an early morning fog. Even in a standard office location, the decision to install fluorescent tubes, tungsten spots, or large skylights can have a major effect on the décor of a room (as well as on the mood and the productivity of the occupants). Photographers, however, are interested in more than just the mental images of a given lighting effect. They need technical descriptions of the effect. Being able to describe the light is the first step in being able to control it. Or if the light is not controllable, as is the case in a landscape or an architectural picture, describing the light implies seeing the light well enough to know whether to shoot or to wait until conditions improve. As photographers, we are primarily concerned with the brightness, color, and contrast of a light. In the following pages, we will take a brief look at each. 26 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY Brightness To a photographer, the single most important quality of a light source is its brightness. A brighter light is almost always a better light. At the most basic level, if the light is not bright enough, we cannot get a picture. If the light is brighter than the minimum we must have, then we can probably get a better picture. Those photographers who still use film can use a smaller aperture or a faster shutter speed if they have more light. If they do not need, or want, a smaller lens opening or a shorter exposure time, then more light allows using a slower, finer-grained film. Either way, the image quality improves. Color We can use light of any color we please, and very strongly colored lights frequently make an artistic contribution to the photograph. Nevertheless, most pictures are made with white light. However, even this so-called “white” light comes in a range of colors. Photographers consider light to be “white” when it is a roughly even mix of the three primary colors: red, blue, and green. Human beings perceive this combination of light colors to be colorless. The proportions of the color mixture may vary to a great extent, and people still cannot perceive any difference, unless they have the different light sources side by side for comparison. The eye can detect a very slight change in the color mixture, but the brain refuses to admit the difference. As long as there is a reasonable amount of each primary color, the brain says, “This light is white.” Digital cameras make the same automatic adjustment to color that the brain does, but often not as reliably. Photographers must 27 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY therefore pay attention to the differences between various white light sources. To classify variations in the color of white light, photographers borrow the color temperature scale from physicists. The color temperature scale is based on the fact that if we heat a material in a vacuum hot enough, it will glow. The color of this glow depends on how much we heat the material. We measure color temperature in degrees on the Kelvin temperature scale. The measurement unit, degrees Kelvin, is simply abbreviated as “K.” It is interesting to note that the light with a high color temperature is composed of a disproportionate amount of those colors artists call cool. For example, 10,000°K light has a great deal of blue in it. Similarly, what physicists tell us is a low temperature source has many of those colors artists call warm. Thus, a 2,000°K light tends toward the red to yellow family of colors. (None of this is surprising. Any welder can tell us that the blue-white welding arc is hotter than the piece of red-hot metal getting welded.) Traditionally, photographers have used three standard light color temperatures. One of these is 5,500°K and is called daylight. There are two tungsten color temperature standards, 3,200°K and 3,400°K. The last two are close enough together that sometimes the difference between them does not matter. These three light standards were developed for film, and we can still buy film that is color balanced for any of these three light color standards. Digital cameras, however, offer much more flexibility by adjusting numbers in the data processing to effectively allow shooting properly color balanced pictures, not only with light temperatures between any two of the three standards but also at 28 temperatures much lower than 3,200°K and much higher than 5,500°K. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY Contrast The third important characteristic of a photographic light is its contrast. A light source has high contrast if its rays all strike the subject from nearly the same angle. Light rays from a lowcontrast source strike the subject from many different angles. Sunlight on a clear day is a common example of a high-contrast light source. The rays of sunlight shown in Figure 2.4 are parallel to one another and all strike the subject from approximately the same angle (despite the apparent difference in angle caused here by having to draw three dimensions on flat paper). The easiest way to recognize a high-contrast light source is the appearance of the shadows. In the diagram we see that light does not enter the shadow area. This causes the edge of the shadow to be quite sharp and clearly defined. 2.4 The rays from a small, high-contrast light source all strike a subject at approximately the same angle. This produces hard-edged shadows. 29 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY 2.5 Hard-edged shadows are characteristically produced by small light sources. We made Figure 2.5 with such a light source. Notice the crisp, relatively hard-edged shadow. A shadow with such defined edges is called a hard shadow. For this reason, high-contrast light sources are also said to be hard lights. Now let us imagine what happens when cloud cover obscures the sun. Look at Figure 2.6. 2.6 30 The cloud scatters the sun’s light rays, causing them to strike the subject from many angles. This produces the soft shadow characteristic of large lights. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY The sunlight scatters as it passes through the cloud. Consequently, the light that passes through the clouds strikes the subject from many different angles. Therefore, on an overcast day sunlight becomes a low-contrast light source. Again, the contrast of the light source is revealed by the appearance of the shadow it produces. Some of the rays of light partly illuminate the shadow, especially at its edge. This difference is apparent in Figure 2.7. In the photograph using low-contrast light, the shadow of the pepper is no longer clearly defined. It is no longer “hard.” The viewer cannot decide exactly what part of the tabletop is in shadow and what is not. A shadow such as this one, with no clearly defined edge, is called a soft shadow, and the light producing it is called a soft light. Notice that we are using the words “hard” and “soft” only to describe how sharply the edge of a shadow is defined. We are not using these terms to describe how light or dark the shadow is. A soft shadow may be either light or dark, just as a hard shadow may be either light or dark, depending on factors such as 2.7 A shadow so soft that much of it is just barely visible is the result of a very large light source. 31 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY the surface on which it falls and how much light gets reflected into the shadow by nearby objects. For single light sources, the size of that source is the primary factor influencing its contrast. A small light source is always a hard light source, and most large sources are soft ones. We see that the sun in Figure 2.4 occupies little area in the diagram, so it is a small light source. The cloud covers a greater area in Figure 2.6, making it a large light source. It is important to understand that the physical size of a light does not always completely determine its effective size as a photographic light source. We know, for example, that the sun is more than 1 million kilometers in diameter. However, it is far enough away to act as a small source for a photographic subject on Earth. If we could move the sun close enough to us, it would become an extremely large light source. We could then make softly lit photographs in sunlight, even without any cloud cover, assuming we could find a solution to the heat problem! Another extreme example has a more practical use: a small lamp on a laboratory workbench can effectively be a large source if we put it close enough to a tiny insect specimen. Be aware, however, that the correlation between the size of a light source and its contrast is just a generality, not an absolute. Remember that we can optically alter a light with special attachments, or, as photographers call them, “modifiers.” For example, a spot attachment can focus the light rays of a strobe head, and a grid blocks the rays from all but a narrow range of angles. In neither case can the light strike the subject from many different angles. This makes a light equipped with such a device hard, regardless of its size. 32 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY The Contrast of a Photograph The contrast of the light is only one of the influences on the contrast of a photograph. If you are an experienced photographer, you know that you can find high contrast in an image with low-contrast light and vice versa. Contrast is also determined by subject matter composition, exposure, and, if you are using film, its development. As everyone knows, a scene that includes black and white subjects is likely to have more contrast than one with entirely gray objects; but a software Levels or Curves adjustment during postproduction can produce high contrast, even in an entirely gray scene in very-low-contrast lighting. The relationship between exposure and contrast is a bit more complex. Increased and decreased exposure can reduce contrast in an average scene. However, increasing exposure will increase contrast in a dark-toned subject, whereas decreasing exposure may increase contrast in a light-gray scene. We will talk about the relationship between lighting and contrast throughout this book, and we will show how exposure affects contrast in Chapter 9. “LIGHT” VERSUS “LIGHTING” We have talked about the brightness, color, and contrast of light. These are all of the important characteristics of light. However, we have said very little about lighting. Indeed, the little we have said about lighting has more to do with the absence of light, the shadows, than with the light itself. Shadow is that part of the scene that the majority of the light in that scene does not strike. Highlight is the area illuminated. We want to talk about highlight, but we are not quite ready for it. If you look at the two pepper pictures (Figures 2.5 and 2.7), you will see why. The two photographs have very different lighting. However, even though the highlights are different, typically most viewers will notice only the difference in the shadows. Is it possible that lighting determines the appearance of the shadow, but not the highlight? Figures 2.8 and 2.9 prove otherwise. 33 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY 2.8 A small light source produces small, hard highlights on this glass bottle. Compare these with the highlights in Figure 2.9. 34 The glass bottle in Figure 2.8 was illuminated by a small, highcontrast light source. Figure 2.9, on the other hand, is the result of a large, soft source. Now the difference in the highlights is obvious. Why does the contrast of the light have such a dramatic effect on the appearance of the highlight on the bottle but less so on the LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY 2.9 We produced this large highlight by using a large light source. pepper? As you look at the examples, you already know that the difference in the lighting is caused by the subject itself. The key point to grasp here is that photographic lighting is more than just light. Lighting is a relationship between the light, the subject, and the viewer. Thus, if we want to say any more about lighting, we must now talk about the subject. 35 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY HOW THE SUBJECT AFFECTS LIGHTING Photons move. Photographic subjects often sit still. This is why we tend to consider light to be the “active” player in the photographic event. But this attitude can handicap our ability to “see” a scene. Two identical photons striking two different surfaces can appear dramatically different to the eye and to the camera. The subject changes the light, and different subjects change the light in different ways. The subject plays an active role, just as the photon does. To perceive or to control lighting, we have to understand how the subject does that. The subject can do three things to a photon that strikes it: it can transmit, absorb, or reflect that photon. Transmission 36 Light that passes through the subject, as in Figure 2.10, is said to be transmitted. Clean air and clear glass are examples of common materials that transmit light. Showing you a photograph of transmitted light would be useless. A subject that only transmits the light cannot be seen. The subject that does not alter the light in some way is invisible. Of the three basic interactions between the light and the subject, simple transmission is the least significant in a discussion of photographic lighting. However, the simple transmission shown in Figure 2.10 can occur only if the light strikes the surface at an angle perpendicular to it. At any other angle, the transmission of the light has accompanying refraction. Refraction is the bending of rays of light as they are transmitted from one material to another. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY IL Glass v 2.10 Transmitted light. Clear glass and clean air are common materials that transmit visible light well. Some materials refract light more than others. Air, for example, refracts light very little, whereas the glass used in a camera lens refracts it a great deal. Figure 2.11 illustrates the phenomenon. Refraction is caused by a variation in the speed of light that results from the material through which it is transmitted. (The speed of light is constant in a vacuum.) The light in Figure 2.11 is slowed as it enters the denser glass. The photons that strike the glass first are the first to have their speed reduced. The other photons, still in air, race ahead, causing a bending of the ray. Then the ray bends a second time, but in the opposite direction, as each photon regains its speed upon exiting back into the air. Unlike simple transmission, refraction can be photographed. This is one of the reasons that completely transparent subjects 37 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY Refracted Refracted Ray Ray \ \ Air Glass Refracted Ray 2.11 \ A light ray striking a light-transmitting material—at any angle other than perpendicular—bends. This bending is called refraction. Dense glass, such as that used for camera lenses, refracts light especially strongly. 2.12 The foreground bottle refracts the image of the 38 cocktail glass in back of it. \ s LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY are not invisible. It is, for example, refraction that causes the wavy edge of the Martini glass in Figure 2.12. “Direct” Versus “Diffuse” Transmission So far we have talked about direct transmission, in which light passes through a material in a predictable path. Materials such as white glass and thin paper scatter the light rays in many random, unpredictable directions as they pass through. This scattering is called diffuse transmission (see Figure 2.13). Materials that produce diffuse transmission are called translucent to distinguish them from transparent materials, such as clear glass, which do not significantly diffuse the light. Diffuse transmission is more important when we talk about light sources than in discussing photographic subjects. Covering a Air White Acrylic 2.13 Diffuse transmission is the scattering of light as it passes through a translucent material. 39 LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY small light with a large translucent material is one way to increase its size and, therefore, to soften it. Both a diffusion sheet in front of a strobe and clouds covering the sun, as in Figure 2.6, are examples of translucent materials serving such a function. Translucent subjects are of little special importance to photographers because their translucence usually requires no special lighting consideration. This is because they always absorb some of the light and reflect some of the light, in addition to transmitting it. Absorption and reflection are both more major influences on photographic lighting. We will deal with these next. Absorption Light that is absorbed by the subject is never again seen as visible light. The absorbed energy still exists, but the subject emits it in an invisible form, usually heat (see Figure 2.14). Air Air 2.14 40 Light absorbed by a subject is emitted in an invisible form. For the most part, this is heat. LIGHT: THE RAW MATERIAL OF PHOTOGRAPHY Like transmission, simple absorption cannot be photographed. It is “visible” only when we compare it to other light in the scene that is not absorbed. This is why highly light-absorbing subjects, such as black velvet or black fur, are among the most difficult things to photograph. Most subjects absorb part, but not all, of the light striking them. This partial absorption of light is one of the factors that determine whether we see a given subject as black, white, or some intermediate gray. Any particular subject will also absorb some frequencies of light more than others. This selective absorption of certain light frequencies is one of the factors determining the color of a subject. Reflection Reflection is light striking a subject and bouncing off it. You know that fact already. The concept is easy because we use it daily. Reflection makes vision possible. We do not see objects; we see light. Because most objects produce no light, their visibility depends entirely on light reflected from them. Thus, there is no need to show you a photograph of reflection. Almost any picture you have on hand will serve the purpose. However, the familiarity of reflection does not mean that it needs no further discussion. On the contrary, its extraordinary importance demands that we devote most of the next chapter to it. 41 42 3 The Management of Reflection and the Family of Angles In the previous chapter we looked at light and how it behaves. We learned that the three most important qualities of any light source are its brightness, color, and contrast. We also learned that the subject, not just the light, has a major influence on lighting. A subject can transmit, absorb, or reflect the light that strikes it. Of the three ways the subject can affect the lighting, reflection is the most visible. Highly transparent subjects have minimal effect on light, so they tend to be invisible. Highly absorbent subjects may also be invisible because they convert light into other forms of energy, such as heat, which we cannot see. Photographic lighting, therefore, is primarily an exercise in reflection management. Understanding and managing reflection, for the result you want, is what constitutes good lighting. In this section, we will look at how subjects reflect light and how to capitalize on those reflections. We will begin our discussion of reflection with a “thought experiment.” We would like you to create three different images in your mind. First, on a desktop, imagine a piece of very thick, 43 REFLECTION AND THE FAMILY OF ANGLES perfectly smooth, gray paper. The gray should be a medium one, light enough to write on but dark enough that no one would confuse it with white. Next, visualize a piece of metal of the same size as the paper. We suggest old pewter. The metal should also be smooth and exactly the same gray as the paper. Third, make a mental ceramic tile, very glossy and the same shade of gray as the other two subjects. Finally, put the three mental images together on the same desk and examine the differences you see in the three subjects. Notice that none of the subjects transmits any light. (That is why we made the paper thick.) Furthermore, they all appear to absorb the same amount of light (because they are all the same gray). Yet the difference in the three subjects is apparent. You have seen it. (If not, try again, and you will, now that you know we expect you to do so!) The reason that these subjects, with identical transmission and absorption, appear different is that the subjects reflect the light differently. The reason you can see the differences without looking at examples on this page is that they are part of that visual knowledge you already have stored away in the occipital lobe of your brain. In this chapter, we are not going to tell you very many things your brain does not already know. We will, however, put some of that knowledge into words. This will make it easy for us to talk about reflection for the rest of this book. TYPES OF REFLECTIONS Light can reflect from a subject as diffuse reflection, direct reflec- 44 tion, and polarized direct reflection—or as it is often called, glare. Most surfaces cause some of each of these three types. The REFLECTION AND THE FAMILY OF ANGLES proportions of each type of reflection vary with the subject, and it is the proportion of each reflection in the mix that makes one surface look different from another. We are going to examine each of these types of reflections in some detail. In each case, we will assume that the reflection is a perfect example, uncontaminated by either of the other two. This will make it easier to analyze each of them. (Events in nature sometimes offer nearly perfect examples.) For now, we do not care what type of light source might be producing any of the following examples. Only the reflecting surface matters. Any sort of light could work. Diffuse Reflections Diffuse reflections are the same brightness regardless of the angle from which we view them. This is because the light from the sources is reflected equally in all directions by the surface it strikes. Figure 3.1 shows a diffuse reflection. In it we see light falling on a small white card. Three people are pointing their cameras at it. If each of these individuals were to photograph the white card, each of their pictures would record the subject as the same brightness. On film, the image of the card would have the same density in each negative. Neither the angle of illumination of the light source nor the camera’s angle of view would affect the brightness of the subject in such a picture. Other than in lighting textbooks, no surfaces reflect light in a perfectly diffuse manner. However, white paper approximates such a surface. Now look at Figure 3.2 There is a reason that we chose to put the largely white playing cards in this particular example. All white things produce a great 45 REFLECTION AND THE FAMILY OF ANGLES 3.1 A white card gives off almost nothing but diffuse reflection. Because diffuse reflection from a light source is reflected equally in all directions from the surface, all three cameras see the card as having the same brightness. 3.2 The playing cards in this scene give off a great deal of diffuse reflection. This would 46 appear white from any angle. REFLECTION AND THE FAMILY OF ANGLES deal of diffuse reflection. We know this because they appear white regardless of the angle from which we view them. (Walk around the room you are in now. Look at the white objects and the black objects from different angles. Notice that the apparent brightness of the black objects may change with viewpoint, but the white objects stay about the same.) The contrast of the light source does not affect the appearance of a diffuse reflection. It is worth proving this with one more picture of the same scene. We used a small light for the earlier photograph. We could see that by the hard shadows cast by the objects in it. Now look at Figure 3.3 to see what happens when we use a large light instead. 3.3 The soft shadows in it prove we used a large light to make this picture. 47 REFLECTION AND THE FAMILY OF ANGLES Diffusion Confusion Photographers often diffuse a light source by reflecting the light from an umbrella or by covering it with a translucent material. We call light passing through translucent material diffuse transmission. Now we speak of diffuse reflection. The two concepts have enough in common that we should pay special attention to the differences between them. Diffusing the light source has no effect on whether the reflection is diffuse. Remember that small light sources are always “hard” (undiffused) and that large light sources are almost always “soft” (diffused). The word diffusion is a good one because its meaning is perfectly consistent in both uses. In each case, it means a scattering of the light. But what does the scattering—the light or the subject? The source determines the type of light, and the surface determines the type of reflection. Any light can produce any reflection, depending on the subject. Predictably, the large light source has softened the shadows in the scene, but notice that the highlights on the playing cards look about the same. That is because the diffuse reflection from the surface of the paper is identical to that in Figure 3.2. So now we have seen that neither the angle nor the size of the light source affects the appearance of a diffuse reflection. However, the distance from the light to the surface of the subject does matter. The closer the light gets to the subject, the brighter the subject becomes and—at a given exposure setting— the lighter the subject appears in the finished picture. Specular Reflection and Specular Light Photographers sometimes call direct reflection specular reflection. As a synonym for direct reflection, this is a perfectly good term. If you use the word specular in this way, please feel free to substitute the words as you read direct reflection. However, some photographers also use specular to mean smaller, brighter highlights within a large one; others mean highlights created by a small light source. 48 REFLECTION AND THE FAMILY OF ANGLES Direct reflection does not necessarily imply either of these. Because specular reflection has different meanings for different people, we will not use the term in this book. Modern usage adds further inconsistency. Originally, specular was used to describe only the reflection, not the source of the light. (The Greek root means “mirror.”) Today, some photographers use specular light as a synonym for hard light, but a “specular” light source does not necessarily produce a “specular” reflection. A hard light is always hard, but the way it reflects depends on the surface of the subject. So we will always call specular lights hard to make it clear that we are talking about the light, not the reflection. The Inverse Square Law A diffuse reflection gets brighter if we move the light source closer to the subject. If we needed, we could calculate this change in brightness with the inverse square law. The inverse square law says that intensity is inversely proportional to the square of the distance. Thus, a light at any particular distance from the subject will light the subject with an intensity four times as bright as the same light twice as far away. Similarly, a light will have nine times the intensity of the same light moved three times as far from the subject. As the intensity of the light falling on the subject varies, so does that of the diffuse reflection. Ignoring the math, this simply means that reflection from a surface gets brighter if we move the light closer and it gets dimmer if we move the light farther away. Intuitively, this seems immediately obvious. Why even bother to mention it? Because such intuition is often misleading. Some subjects, as we shall soon see, do not produce brighter reflections as the light moves closer to them. 49 REFLECTION AND THE FAMILY OF ANGLES Direct Reflections Direct reflections are a mirror image of the light source that produces them. They are also called specular reflections. Figure 3.4 is similar to Figure 3.1, but this time we have replaced the white card with a shiny saw blade. Both the light source and the observers are in the same positions as they were in Figure 3.1. Notice what happens. This time one of the three cameras now sees a bright reflection, whereas the others see no reflection at all. This diagram illustrates the direct reflection produced when a light is directed at a surface such as polished metal or glass. The light rays bounce from the smooth surface at the same angle at which they hit it. More precisely stated, the angle of incidence equals the angle of reflectance. This means that the point at which 3.4 Direct reflection. Looking at the diagram, the camera with an arrow path pointing at it sees a bright reflection of the light source. The others, however, see no reflection 50 of it at all. REFLECTION AND THE FAMILY OF ANGLES direct reflections can be seen is exactly determined by the angles between the light source, the subject, and the camera viewpoint. Those cameras positioned on each side receive no reflected light rays. From their viewpoint, the saw blade would appear dark. None of the rays from the light source is reflected in their direction because they are not viewing the saw from the one (and only) angle in which the direct reflection of the light source can happen. However, the camera that is directly in line with the reflection sees a spot in the reflective surface almost as bright as the light source itself. This is because the angle from its position to the reflective surface is the same as the angle from the light source to the reflective surface. Again, no real subject produces a perfect direct reflection. Brightly polished metal, water, or glass may nearly do so, however. Breaking the Inverse Square Law? Did it alarm you to read that the camera that sees the direct reflection will record an image as bright as the light source? How do we know how bright the direct reflection will be if we do not even know how far away the light source is? We do not need to know how far away the source is. The brightness of the image of a direct reflection is the same regardless of the distance from the source. This principle seems to stand in flagrant defiance of the inverse square law, but an easy experiment will show why it does not. You can prove this to yourself, if you like, by positioning a mirror so that you can see a lamp reflected in it. If you move the mirror closer to the lamp, it will be apparent to your eye that the brightness of the lamp remains constant. Notice, however, that the size of the reflection of the lamp does change. This change in size keeps the inverse square law from being violated. If we move the lamp to half the distance, the mirror will reflect four times as much light, just as the inverse square law predicts, but the image of the reflection covers four times the area. So that image still has the same brightness in the picture. As a concrete analogy, if we spread four times the butter on a piece of bread of four times the area, the thickness of the layer of butter stays the same. 51 REFLECTION AND THE FAMILY OF ANGLES 3.5 Two clues tell us this picture was made with a small light source: hard shadows and the size of the reflection in the hand saw. 52 Now we will look at a photograph of the scene in Figure 3.5. Once again, we will begin with a high-contrast light source. The saw blade in Figure 3.5 has a shiny surface. Here we see two indications that the light source is small. Once again, the shadows are hard. In addition, we can also tell that the source is small because it is reflected in the shiny surface of the saw. Because the image of the light source is visible, we can easily anticipate the effect of an increase in the size of the light. This allows us to plan the size of the highlights on shiny surfaces. Now look at Figure 3.6. REFLECTION AND THE FAMILY OF ANGLES 3.6 A larger light softens shadows. More important, however, is that the reflection of the light now completely fills the saw. This is because the light we used this time was large enough to fill the family of angles that causes direct reflection. Once again, the large, soft light source we now use produces very soft shadows. The picture is more pleasing, but that is not the important aspect. More important is the fact that the reflected image of the large light source completely covers the saw. In other words, the larger light source fills the family of angles that causes direct reflection. This family of angles is one of the most useful concepts in photographic lighting. We will now discuss that family in more detail. 53 REFLECTION AND THE FAMILY OF ANGLES The Family of Angles Our previous diagrams have been concerned with only a single point on a reflective surface. In reality, however, each surface is made up of an infinite number of points. A viewer looking at a surface sees each of these points at a slightly different angle. Taken together, these different angles make up the family of angles that produces direct reflection. In theory, we could also talk about the family of angles that produces diffuse reflection. However, such an idea would be meaningless because diffuse reflection can come from a light source at any angle. Therefore, when we use the phrase “family of angles” we will always mean those angles that produce direct reflection. This family of angles is important to photographers because it determines where we should place our lights. We know that light rays will always reflect from a polished surface, such as metal or glass, at the same angle as that at which they strike it. So we can easily determine where the family of angles is located, relative to the camera and the light source. This allows us to control if and where any direct reflection will appear in our picture. Figure 3.7 shows the effect of lights located both inside and outside this family of angles. As you can see from it, any light positioned within the family of angles will produce a direct reflection. Consequently, any light positioned outside of the family of angles will not light a mirror-like subject at all, at least as far as the camera can see. Photographers sometimes want to see direct reflection from most of the surface of a mirror-like subject. This requires that they use (or find in nature) a light large enough to fill the family of angles. In other scenes, they do not want to see any direct 54 reflection at all on the subject. In those instances, they must place REFLECTION AND THE FAMILY OF ANGLES 3.7 The light positioned within the family of angles will produce direct reflection. The other light, outside the family of angles, will not. both the camera and the light so that the light source is not located within the family of angles. We will use this principle repeatedly in the coming chapters. Polarized Direct Reflection A polarized direct reflection is so similar to an ordinary direct reflection that photographers often treat them as the same. However, these reflections offer photographers several specialized techniques and tools for dealing with them. Like the direct reflection, only one viewer in Figure 3.8 will see the reflection. Unlike the direct reflection, an image of the polarized reflection is always substantially dimmer than a photograph of the light source itself. 55 REFLECTION AND THE FAMILY OF ANGLES 3.8 56 Polarized direct reflection looks like un-polarized direct reflection, only dimmer. A perfectly polarized direct reflection is exactly half as bright as an un-polarized one (provided the light source itself is not polarized). However, because polarization is inevitably accompanied by absorption, the reflections we see in the scene are more likely to be much dimmer than that. To see why polarized reflection cannot be as bright as an unpolarized direct reflection, we need to know a bit about polarized light. We have seen that the electromagnetic field fluctuates around a moving photon. Figure 3.9 represents this fluctuating field as a jump rope being swung between two children. One child is spinning the rope while the other simply holds it. Now, let’s put up a picket fence between the children, as shown in Figure 3.10. The rope now bounces up and down instead of swinging in an arc. This bouncing rope resembles the electromagnetic field along the path of a photon of polarized light. REFLECTION AND THE FAMILY OF ANGLES 3.9 The oscillating electromagnetic field around a photon represented as a jump rope. The child on the left is spinning the rope while the one on the right holds on. 3.10 When the children spin the rope through the picket fence, it bounces up and down instead of spinning in an arc. A polarizing filter blocks the oscillation of light energy in much the same way. Molecules in a polarizing filter block the oscillation of the light energy in one direction, just as the picket fence does to the oscillating energy of the jump rope. The molecular structure of some reflecting surfaces also blocks part of the energy of the photon in the same manner. We see such a photon as a polarized reflection or glare. Now, suppose, not being satisfied with eliminating just a part of the children’s play, we install a horizontal fence in front of the first, as shown in Figure 3.11. 57 REFLECTION AND THE FAMILY OF ANGLES 3.11 Because we have added a horizontal fence to the first, when one child spins the rope, the other will see no movement. With the second fence in place, if one child spins the rope, the other sees no rope movement at all. The crossed picket fences block the transmission of energy from one end of the rope to the other. Crossing the axes of two polarizing filters blocks the transmission of light, just as the two picket fences do with rope energy. Figure 3.12 shows the result. Where the polarizers overlap with their axes perpendicular, none of the type is visible on the 3.12 58 The axes on the two overlapping polarizers are perpendicular. They block light much as the two fences did with the energy of the jump rope. REFLECTION AND THE FAMILY OF ANGLES page. The transmission of light reflected from the page to the camera has been completely blocked. A lake, painted metal, glossy wood, or plastic can all produce polarized reflection. Like the other types of reflections, the polarization is not perfect. Some diffuse reflection and some un-polarized direct reflection are mixed with the glare. Glossy subjects produce a greater amount of polarized reflection, but even matte surfaces produce a certain amount. Polarized direct reflection is more visible if the subject is black or transparent. Black and transparent subjects do not necessarily produce stronger direct reflections than white ones. Instead, they produce weaker diffuse reflection, making it easier to see the direct reflection. This is why you saw the change in apparent brightness of the black objects, but not of the white ones, when you walked around your room a while ago. Glossy black plastic can show us enough polarized reflection to make a good example. The scene in Figure 3.13 includes a black plastic mask and a white feather on a sheet of glossy black plastic. We used the same camera and light position as in the pictures of Figure 3.4 and mirrored surface. You can tell by the size of the reflections that we used a large light source. Both the mask and the plastic sheet produce nearly perfect polarized reflection. From this angle, glossy plastic produces almost no unpolarized direct reflection; black things never produce much diffuse reflection. However, the 3.13 The glossy sheet and mask produce feather behaves quite differently. It produces almost nothing but diffuse reflection. almost nothing but polarized direct reflection. In contrast, the white feather gives off almost nothing but diffuse reflection. 59 REFLECTION AND THE FAMILY OF ANGLES The light source was large enough to fill the family of angles defined by the plastic sheet, creating direct reflection over the entire surface. The same light was large enough to fill only part of the family of angles defined by the mask. We know this because of the highlights we see only on the front of the mask. Now look at Figure 3.14. We made it with the same arrangement used in the previous picture, but now we’ve placed a polarizing filter over the camera lens. Because polarized reflection was almost the only reflection from the black plastic in 3.14 A polarizer over the camera lens blocks the Figure 3.14, and because the polarizing filter polarized direct reflection. Thus, only the feather— blocks glare, little of the light reflected from which gives off diffuse reflection—is clearly visible. any of the black plastic items photographed reached the camera. As a result, the plastic now looks black. We did have to open our aperture by about two stops to compensate for the neutral density of the polarizing filter. How do you know that we did not accidentally miscalculate the exposure? (Maybe we did so deliberately, just to get the image dark enough to prove our point.) The feather proves that we did not. The polarizer did not block the diffuse reflection from the feather. So with accurate exposure compensation, the feather is about the same light gray in both pictures. Is It Polarized Reflection or Ordinary Direct Reflection? Polarized and un-polarized direct reflections often have similar 60 appearance. Photographers, out of need or curiosity, may want to distinguish one from the other. REFLECTION AND THE FAMILY OF ANGLES We know that direct reflection appears as bright as the light source, whereas polarized direct reflection appears dimmer. However, brightness alone will not tell us which is which. Remember that real subjects produce a mixture of reflection types. A surface that seems to have polarized reflection may actually have weak direct, plus some diffuse, reflection. Here are a few guidelines that tend to tell us whether a direct reflection is polarized: • If the surface is made of a material that conducts electricity (metal is the most common example), its reflection is likely to be un-polarized. Electrical insulators such as plastic, glass, and ceramics are more likely to produce polarized reflection. • If the surface looks like a mirror—for example, bright metal— the reflection is likely to be simple direct reflection, not glare. • If the surface does not have a mirror-like appearance—for example, polished wood or leather—the reflection is more likely to be polarized if the camera is seeing it at an angle of 40 to 50 degrees. (The exact angle depends on the subject material.) At other angles, the reflection is more likely to be unpolarized direct reflection. • The conclusive test, however, is the appearance of the subject through a polarizing filter. If the polarizer eliminates the reflection, then that reflection is polarized. • If, however, the polarizer has no effect on the suspect reflection, then it is ordinary direct reflection. If the polarizer reduces the brightness of the reflection but does not eliminate it, then it is a mixed reflection. 61 REFLECTION AND THE FAMILY OF ANGLES Turning Ordinary Direct Reflection into Polarized Reflection Photographers often prefer that a reflection be polarized reflection so that they can manage it with a polarizing filter mounted on their camera lens. If the reflection is not glare, the polarizer on the lens will have no effect except to add neutral density. Increasing Polarized Reflection Most photographers know that polarizers can eliminate polarized reflection they do not want, but in some scenes we may like the polarized reflection and want even more of it. In such cases we can use the polarizer to effectively increase the polarized reflection. We do this by rotating the polarizing filter 90 degrees from the orientation that reduces reflection. The polarized light then passes through easily. It is important to understand that a polarizer always blocks some un-polarized light. By doing this, in effect, it becomes a neutral density filter that affects everything except direct reflection. Thus, when we increase the exposure to compensate for the neutral density, the direct reflection increases even more. However, placing a polarizing filter over the light source will turn a direct reflection into polarized reflection. A polarizer on the camera lens can then manage the reflection nicely. Polarized light sources are not restricted to studio lighting. The open sky often serves as a beautifully functional polarized light source. Facing the subject from an angle that reflects the most polarized part of the sky can make the lens-polarizing filter effective. This is why photographers sometimes find polarizing filters useful on subjects such as bright metal, even though the filter manufacturer may have told them that polarizers have no effect on such subjects. In those cases, the subject is reflecting a polarized source. 62 REFLECTION AND THE FAMILY OF ANGLES APPLYING THE THEORY Excellent recording of a subject requires more than focusing the camera properly and exposing the picture accurately. The subject and the light have a relationship with each other. In a good photograph, the light is appropriate to the subject and the subject is appropriate to the light. The meaning of appropriate is the creative decision of the photographer. Any decision the photographer makes is likely to be appropriate if it is guided by understanding and awareness of how the subject and the light together produce an image. We decide what type of reflection is important to the subject and then capitalize on it. In the studio, this means manipulating the light. Outside the studio, it often means putting the camera in position, anticipating the movement of the sun and clouds, waiting for the right time of day, or otherwise finding the light that works. In either case, the job is easier for the photographer who has learned to see what the light is doing and to imagine what it could do. 63 64 4 Surface Appearances All surfaces produce diffuse, direct, and polarized reflection in varying degrees. We see all of these reflections, but we are not always conscious of them. Years of programming enable our brains to edit the image of the scene. This editing minimizes reflection that is distracting or trivial to the subject. At the same time, it maximizes the importance of whatever light is essential to our comprehension of the scene. The psychological image in the brain may be quite different from the photochemical one the eye actually sees. Psychologists have not completely explained why this difference exists. Movement certainly has something to do with it, but not everything. Some visual defects are less disturbing in a motion picture than they might be in a still photograph, but not much. Photographers know that our brains cannot edit an image of a scene as well as they can the scene itself. We discovered that fact when we learned how quickly we could spot defects in our images, even though we could not see them at all when we carefully examined the original scene. Unconscious parts of our brain did us the “service” of editing the scene to delete extraneous and 65 SURFACE APPEARANCES contradictory data. A viewer, however, becomes fully conscious of the same details upon seeing the picture. And just how do pictures reveal details we might never otherwise notice? This is a question for another book. This book is about what we need to do about that fact and how to take advantage of it. When we make a picture we have to consciously do some of the editing that other observers do unconsciously. PHOTOGRAPHER AS AN EDITOR Photographic lighting deals mainly with the extremes: the highlights and the shadows. When we are happy with the appearance of these two, we are likely to be pleased with the middle range also. Highlight and shadow together reveal form, shape, and depth. But highlight alone is usually enough to reveal what the surface of an object is like. In this chapter we will concern ourselves primarily with highlight and surface. Most of our example subjects will be flat—two dimensional, or nearly so. In Chapter 5 we will complicate matters a bit with three-dimensional subjects and a more detailed discussion of shadow. In the previous chapter, we saw that all surfaces produce both diffuse and direct reflections and that some of the direct reflections are polarized. But most surfaces do not produce an even mix of these three types of reflections. Some surfaces produce a great deal more of one than another. The difference in the amounts of each of these reflections determines what makes one surface look different from another. One of the first steps in lighting a scene is to look at the subject 66 and decide what kind of reflection causes the subject to appear the way it does. The next step is to position the light, the subject, SURFACE APPEARANCES and the camera to make the photograph capitalize on that type of reflection and minimize the others. When we do this we decide what kind of reflection we want the viewers to see. Then we engineer the shot to make sure they see that reflection and not others. “Position the light” and “engineer the shot” imply moving light stands around a studio, but we don’t necessarily mean that. We do exactly the same thing when we pick the camera viewpoint, day, and time outside the studio. We will use studio examples in this chapter simply because they are easy for us to control to demonstrate the specifics clearly. The principles apply to any type of photography. In the rest of this chapter, we will see some examples of subjects that require us to capitalize on each of the basic kinds of reflections. We will also look at what happens when we photograph reflections that are inappropriate to those subjects. CAPITALIZING ON DIFFUSE REFLECTIONS Photographers are sometimes asked to photograph paintings, illustrations, or antique photographs. Such copy work is one simple example of a circumstance in which we usually want only diffuse, and not direct, reflection. Because this is the first concrete demonstration of lighting technique in this book, we will discuss it in great detail. The example shows how an experienced photographer thinks through any lighting arrangement. Beginners will be surprised at the amount of thinking involved in even such simple lighting, but they should not be dismayed by it. Much of this thinking is identical from one picture to the next, and it quickly becomes so habitual that it takes almost no time or 67 SURFACE APPEARANCES effort. You will see this as we progress, and we will omit some of the detail in future chapters. Diffuse reflection gives us the information about how black or how white the subject is. The printed pages of this book have blacks and whites determined by areas that produce a great deal of diffuse reflection—the paper—and those that produce little diffuse reflection—the ink. Because diffuse reflection can reflect light frequencies selectively, it also carries most of the color information about the subject. We could have printed this page with magenta ink on blue paper (if those picky editors would have allowed it), and you would know it because the diffuse reflection from the page would tell you. Notice that diffuse reflection does not tell us very much about what the surface material is. Had we printed this page on smooth leather or glossy plastic instead of paper, the diffuse reflection would still look about the same. (You could, however, tell the difference in material by the direct reflection.) When we copy a painting or another photograph, we are usually not interested in the type of surface on which it was produced; we want to know about the colors and values in the original image. THE ANGLE OF LIGHT What sort of lighting might accomplish this? To answer that question, let us begin by looking at a standard copy set-up and at the family of angles that produces direct reflection. Figure 4.1 shows a standard copy camera arrangement. The camera is on a stand and is aimed at the original art on a copy 68 board beneath it. Assume that the height of the camera is set so that the image of the original art exactly fills the image area. SURFACE APPEARANCES 4.1 The family of angles that produces direct reflections in a “copy” lighting set-up. The light inside the family of angles will produce direct reflection; the other will not. There is a similar family of angles on each side of the camera. We have drawn the family of angles from which a light, or lights, can produce direct reflection. Most copy arrangements use a light on each side of the camera. We need only one light to see the principle. Such a diagram makes it easy to light the set-up. Once again, any light within the family of angles will produce direct reflection, and a light located outside that family will not. We also know from Chapter 3 that a light can produce diffuse reflection from any angle. Because we want only diffuse reflection, we place the light anywhere outside the family of angles. In Figure 4.2 the folk painting is photographed with the light placed outside of the family of angles. We see only diffuse reflection from the surface, and the tone values in the photograph closely approximate the original. 69 SURFACE APPEARANCES 4.2 In a good image, the folk painting we see has nothing but diffuse reflections, and the tones closely resemble those in the original. 4.3 Placing the light inside the family of angles caused an unacceptable hot spot on the image. 70 By way of contrast, in Figure 4.3 the light was inside the family of angles. The resulting direct reflection causes an unacceptable “hot spot” on the painting’s surface. SURFACE APPEARANCES This is all straightforward in the studio or the laboratory. However, photographers are also asked to photograph large paintings in museums or other locations from which they cannot be removed. Anyone who has ever done this knows that museum curators always place display cases or pedestals exactly where we want to put the camera. In such situations, we need to place the camera closer to the subject than we might otherwise. We then switch to a wide-angle lens to get the whole subject to fit the image area. Figure 4.4 is a bird’s-eye view of our museum set-up. Now the camera has a very wide-angle lens with about a 90-degree horizontal angle of view. IL_~DiSPlay_case_~1 4.4 The family of angles has grown much larger in this arrangement using a wide-angle lens. The result is a small range of acceptable lighting angles. Only the light outside the family of angles will produce glare-free lighting. 71 SURFACE APPEARANCES Look what has happened to our family of angles. The family of angles causing direct reflection has grown much larger, and the range of acceptable angles for copy lighting is much smaller. The light now needs to be much farther to the side to avoid unacceptable direct reflections. Shooting a copy with the camera in this position would yield drastically inferior results if we kept the light where we had it in Figure 4.1. The same lighting angle that works well when the camera is farther away can cause direct reflection if the camera is closer. In this case, we would have to move the light farther to the side. Finally, notice that in some museum-like situations, the shape of the room may make the placement of the lights more difficult than 4.5 A copy set-up using a long lens. Because the family of angles that produces a direct reflection is small, finding a good place to put the light is usually easy. (Had the wall on the right been a bit closer, however, it would have begun to limit the light 72 placement. We will deal with such a problem below.) SURFACE APPEARANCES that of the camera. If it seems impossible to position the lights to avoid direct reflection, we sometimes can solve the problem just by moving the camera farther away from the subject (and using a correspondingly longer lens to obtain a large enough image size). In Figure 4.5, the room is too narrow to allow easy light placement, but it is deep enough to allow the camera to be placed at almost any distance. We see that when the camera is farther from the subject, the family of angles that produces direct reflection is small. Now it is easy to find a lighting angle that avoids direct reflection. THE SUCCESS AND FAILURE OF THE GENERAL RULE Texts that attempt simply to demonstrate basic copy work (as opposed to general lighting principles) often use a diagram similar to Figure 4.6 to represent a standard copy set-up. 4.6 The “standard” copy set-up sometimes produces good results and sometimes does not. A usable lighting angle depends @52 also on the distance between the camera and subject and the choice of lens focal length. 45 ° 45 ° 73 SURFACE APPEARANCES Notice that the light is at a 45-degree angle to the original. There is nothing magic about such an angle. It is a general rule that usually works—but not always. As we saw in the previous example, a usable lighting angle depends on the distance between the camera and the subject and the resulting choice of lens focal length. More important, we need to notice that this rule may fail to produce good lighting if we do not give attention to the distance between the light and the subject. To see why, we will combine the principle in Figure 4.1 with that of Figure 4.6. In Figure 4.7, we see two possible light positions. Both lights are at a 45-degree angle to the subject, but only one of them will produce acceptable lighting. The light that is closer to the subject is within the family of angles that produces direct reflection and 45 ° 4.7 The importance of the distance from the light to the subject. Both of the lights shown are at 45 degrees to the center of the subject, but only one is satisfactory. The 74 light inside the family of angles will produce direct reflection. SURFACE APPEARANCES will cause a hot spot on the surface. The other light is far enough away to be outside the family of angles and will illuminate the surface nicely. So we see that the 45-degree rule will work fine if the photographer gets the lights far enough away from the subject surface. In fact, the rule often does serve well because photographers generally do move the lights farther away from the subject for yet another reason—to obtain even illumination. THE DISTANCE OF LIGHT Up to now we’ve only considered the angle of the light, not its distance. But clearly that’s important too, because we know that diffuse reflections get brighter as the light gets closer to the reflecting surface. Figure 4.8 revisits an earlier arrangement, now emphasizing the distance of the light. 4.8 The shallow angle that avoids direct reflection is also more likely to cause uneven illumination if we don’t take care to avoid it. Display Case ~ ~55"~ I I 75 SURFACE APPEARANCES Once again, we are using a wide-angle lens to photograph the subject. Remembering that such situations leave a very small range of angles of illumination that do not cause direct reflection, we have positioned the light at a very shallow angle to the surface. But the edge of the subject that is closer to the light receives so much more light than the edge farther away that uniform exposure is impossible. Figure 4.9 shows the resulting exposure. The shallow lighting angle avoids direct reflection, but it does cause an unacceptable difference in the lighting of the picture’s sides. Obviousl