American cinematographer (Sept 1935)

376 American Cinematographer • September 1935 F rom the time the first "living picture" flickered across a screen, technicians and laymen alike have dreamed of the ideal cinema, which would combine sound, color and natural depth. Today we have accepted sound as a commonplace, and color is edging toward real perfection; the capture of the elusive "third dimension" of depth, alone remains unaccomplished. Popular opinion, in consequence, has seized upon stereoscopy as the next great advance expected of film technique. Scarcely a month goes by without its rumors and printed reports of some new process which will at last bring lifelike relief to the screen: but none of these miracle-working processes have as yet shown up in actual production. A shot-gun fired at a warld map would give a fair idea of the location and the number of inventors who are wrestling with the problem. Literally millions of dollars have been spent in pursuit af the will-a-the-wisp of stere- oscopy. It is not the purpose of this article to make disparaging remarks about the conscientious investigator. I should be glad to help such individuals as much as possible. But I have na use for the promotional inventor who interests people to invest money in schemes he himself knows to be unworkable. I have an almast equal disrespect for him who through ignorance of the technical essentials of the problem he is seeking to solve, squanders the savings of investors. Equally culpable is the sincere worker who in a misguided attempt to avoid plagiarism, neglects to inform himself of what has previously been done in the field. The secret of invention is exact knowledge of one's problem, and of prior attempts at its solutian. The wise investor, too, learns something at least of the fundamentals of the problem before putting up his money. What, then, are the fundamental facts of stereoscopy? We see things stereoscopically because we have binoc- ular vision—because we have two eyes. Conversely, a camera photographs things flat because it has only one eye—its lens. All that is necessary for stereoscopic motion pictures is to have a binocular camera and to present the results to the audience so that each eye sees its appro- priate picture. When we observe a scene, each eye sees a different view; that is, the two pictures are not alike: the various components of the one picture bear a different relationship to each other than they do in the other picture. This is called "parallax." In Figure One, I and I' represent two eyes. A and B represent two posts. Eye I sees post B on the left side of post A; eye I' sees post B on the right side of post A. If we focus our attention on post A— that is, converge our eyes so the principal line of sight of each eye crosses that of its mate at post A—then we shall be conscious that past B is now apparently double. We can quickly change our vision and focus our atten- tion on post B, when it will seem to be a single post; at the same time we are conscious that post A now appears double. It is apparent, then, that two photographs taken Are Third- from points I and I' will not superimpose, for the pictures are dissimilar. We may not at all times be wholly aware of it, but our brain always gets a double impression of every object in the scene we are viewing except that particular point or object upon which we are concentrating at the instant. Each time we change the point of concentration to a closer or more distant point in the scene, all objects which are forward or back af this concentration point are shifted from their former relationship. If the object iri the foreground is narrower than the distance between our eyes, then to our binocular vision no part of the back- ground is obscured. We can actually see around this object. Now, if we make a pair of photographs from positions I and I', and present them in such a way that the be- holder's right eye sees only the picture made from the right-hand viewpoint, and the left eye sees only the left- hand picture, we shall recreate not only form, but the sense of depth and roundness as well. This is what the ordinary stereocope does. The pho- tographs are made in a dual camera, with two lenses ap- proximately 2.V2 inches apart. The prints (which may be either conventional paper positives or transparencies) are viewed in a device which allows each eye to see only its proper print. On a laboratory scale, this can be done with fair suc- cess in motion pictures: but it invariably requires the use of individual viewing-devices by each member of the aud- ience—which rules it out as a commercial proposition. Quite a variety of processes of this type have been pro- posed. Among them are systems in which the two pic- tures are printed on double-coated stock, dyed in comple- mentary colors, and viewed through individual spectacles having lenses of these colors, each of which filters out the unwanted image; others in which synchronized shutters perform the same service; and yet others depending on polarized light to secure the separation. In any event, such systems can hardly be applied to film entertainment as we know it today. So our definition of stereoscopic motion pictures must specify not alone the creation of the illusion of depth and roundness, but a system which will permit us to go into the theatre as we now do—with no eye aids whatsoever—and enjoy this sense of depth and roundness from any seat in the house. A large order, indeed! Surprisingly enough, this can be done with ordinary equipment under more or less normal circumstances; in fact it is being done quite frequently today! But here's the rub—it is done by a trick which can be used in normal production only in rare instances! Many years ago a pic- ture was exhibited, called "Cabiria," in which it was claim- ed stereoscopic results were attained. It was also claimed that the method and apparatus were patented. The prin- ciple was to have the camera always moving on a radial track, with the action taking place at the center of the radius. One can readily visualize the results! The rela- tive motion of the various planes, combined with the ever- changing viewpoint, gave a distinct sense of relief. Every- one is familiar with the effect of relief gained in a motion