THREE-DIMENSIONAL PHOTOGRAPHY P rinci p les of Stereoscopy by HERBERT C. McKAY F. R.P. S. AMERICAN PHOTOGRAPHY BOOK DEPARTMENT New York, N. Y. Copyright 1953 by the AMERICAN PHOTOGRAPHIC PUBLISHING COMPANY Printed in the United States of America AMERICAN BOOK STRATFORD PRESS TO my principal assistant who is also my wife, FRANCES A. McKAY TABLE OF CONTENTS CHAPTER PAGE 1 Elementary Stereography ............. 1 2 Stereoscopic Cameras .............. 12 3 The Stereoscope ................ 28 4 Correlation of Camera and Viewer ......... GO 5 Mounting. Transposition and Spacing ........ 75 6 Stereographic Technique ............. 91 7 Flash in Stereo ................104 8 Color in Stereo ................ 119 9 Pictorial Stereography .............. 131 10 The Nude in Stereo .............. 154 11 Anaglyphs ..................167 12 Stereo Projection ................175 13 Applied Stereoscopy .............. 201 14 Polarized Light Applied to Stereoscopy ........213 15 Types of Stereoscopy ..............218 16 Trick Work .................221 17 Close-up Stereograpliy ..............240 18 Hyperstereo .................260 19 Stereo Movies .................271 20 Special Phases ................. 289 21 Stereo Processing ................304 Appendix A .................313 Appendix B .................318 Appendix C ................. 325 Index ...................329 V INTRODUCTION URING THE TWO YEARS since the first edition of this book D appeared, there has been a profound change in the status of stereo in the United States. Then it was confined to a relatively small number of specialists, today it promises to become the number one medium for amateur photography. The change has been aided by the introduction of small, convenient cameras using 35mm film; it has been given great impetus by the intro- duction of color; it has been made easier by the simplification of mounting and the introduction of commercial mounting services. However, the greatest force of all has been an aggressive publicity campaign sponsored by the makers of the equipment used. This does not mean that the popularity is artificial. Not at all. A brief wave of success could be produced by such means, but the campaign has served only to introduce stereo to the public. Once that introduction has been made, stereo continues to advance by its own merit. Owners of stereo cameras are familiar with one expression which, although it varies widely in actual wording, always remains the same in meaning. It is heard from those who have been familiar with photography all their lives in the way that every American is familiar with it; printed reproductions, casual use of an inexpensive camera, collections of family snapshots. When such people see their first modern stereo they almost always say (1) “I never saw anything like it!” (2) “That’s the only kind of photography I’d be interested in.” (3) “Where can I get a camera to do that kind of work?” I am not a salesman, and do not even try to interest people in the purchase of equipment, yet I have “sold” over 100 stereo cam- eras and almost half that many projectors of which I have defi- nite record (although one dealer or another made the profit incident to these sales!). The fact is mentioned only to show that interest aroused is so deep that those interested are not satisfied until they, too, are making stereos. It is sometimes difficult for an oldtimer, steeped in the tradition of the older stereo, to keep up with the modern pace. The old rules and laws, except the few which are sound, have been thrown vii viii INTRODUCTION overboard-and stereo does not seem to have been harmed by the fact. Stereo used to be reserved for very carefully made expo- sures of subjects selected with equal care, the new stereographer blithely shoots go or 60 shots in an afternoon. All of this has a most important bearing upon the development of the new art, and certainly it must affect our approach to the subject in any kind of discussion. Photography is one of the most conservative of the common arts, foolishly so most of the time. The writer can remember the senseless struggle of the glass plate advocates (which means about gg percent of the serious photog- raphers, professional and amateur) against the encroachment of the sheet film. Today we see the stereo Old Guard tearing their hair and clad in sackcloth and ashes as one after another of their cherished idols falls under the onslaught of the enthusiastic “new stereographer.” But with this Old Guard numbering considerably under 1000 and with the new legion growing at about 20 to 30 thousand every year, the newcomers, fortunately for all con- cerned, are going to have things their own way. The stereographer was once very proud of his theoretical knowledge, whether it was accurate or not, and he used stereo- scopy only as a stepping stone to elementary, very eIementary stereogrammetry, and to him “stereo” was far more grammetric than scopic. Stereoscopy as practised in stereography is a matter of produc- ing a desired visual effect. The appearance is the ultimate goal of the whole process. Therefore, as far as stereography is concerned, errors, mistakenly called “distortions,” if they are invisible simply do not exist. I recall one enthusiastic young mathematician who wrote about PO pages pointing out that a certain stereo tech- nique was not distortionless as claimed, but involved two serious distortions. “Of course,” he added, “these two distortions neutral- ize each other and so are not apparent, but they are there as I have proven!” He simply could not understand that stereo- scopically, the invisible is non-existent. He was delving into the realm of stereogrammetry. Another, this time a stereogrammetric technician, produced an involved mathematical dissertation proving the inevitability of distortion produced by the “magnification” of the viewer. He INTRODUCTION ix could not understand that in ortho-stereo the final magnification is unity, that is, it does not exist visually. Therefore, in this volume we shall deliberately disregard all of these fascinating mathematical complexities and treat our subject from the only rational, stereoscopic point of view; that is, with the visual appearance as the standard. If you can’t see it, it isn’t there. At the same time, most readers will have sufficient curiosity to want to know “why” now and then. Also a superficial knowl- edge of stereo theory will often be of assistance in producing bet- ter work, so a certain amount of theory is necessary. However, it will be kept as elementary as possible. In any event, just re- member that you do not really have to know even this simple theory to enable you to make excellent stereograms. As a matter of fact the writer personally knows two stereogra- phers who cannot even load their cameras, but have the dealer do it, yet they both make perfectly satisfactory stereograms and often produce really beautiful slides! The extent to which you delve into theory is a matter of your own personal choice. But above all remember that stereography is the easiest type of photography, and it can be mastered with little effort. In fact it is just as easy to operate the stereo camera successfully as it is to use the familiar box camera. Stereography is the automatic photography that produces the kind of pictures you have always dreamed of but never really ex- pected to see. The word stereoscopy is compounded from the Greek stereos (solid or firm) and skopos (the act of vision). Thus stereoscopy means the act of seeing “solid,” or actually, seeing in all three dimensions. Stereoscopic photography is the only medium known by which the appearance of an object or scene may be reproduced in every detail so that the image appears to the eyes exactly as did the original object. At first this does not seem to describe more than the ordinary photograph until we stop to recall that the best of conventional photographs falls far short of reproducing “every detail.” The ordinary or planar photograph does not reproduce definite size or distance, it does not distinctly separate every plane, it does not definitely exhibit the depth contour of an ob- x INTRODUCTION ject. In short, it does not reproduce more than a fraction of the essential visual detail of any object. When the stereoscopic photograph is a motion picture in color and with sound, the picture will often deceive the spectator as to its reality. One inherent factor of true stereo, or “orthostereo” as it is called, is that all objects, regardless of the size of the “print,” are reproduced in their full natural size and at their full natural distance. Only those who have enjoyed looking at some well-made stereograms can appreciate the startling realism of these easily made photographs. Any camera may be used for making stereographic negatives; and a simple viewer may be made at home in a few moments by using two inexpensive magnifying lenses. The negatives involve nothing more than making two of them instead of one. That is the sum and substance of elementary stereography. A great deal of very beautiful and costly apparatus has been produced for stereographic purposes, but it is not actually essential. These things, both simple and elaborate, will be discussed each in its proper place. While a poor photographic print may pass muster, the poor stereogram had better not be exhibited. The first requisite is that the stereographer have the ability to make a really good photo- graph. More than this, the fundamental aspects of stereography comprise: 1. Two negatives are made of the same scene but from slightly separated points of view. 2. Thepositives must be transposed, exchanging the right and the left print. 3. The dual print or stereogram is produced by mounting these two prints so that their bases as determined by the camera, shall lie in a common line.