International photographer (Jan-Dec 1935)

Two The INTERNATIONAL PHOTOGRAPHER January, 1935 Applicability of Stereoscopy to Motion Pictures Read before the Society of Motion Picture Engineers and Reprinted by Special Permission of the Author. By LEWIS W. PHYSIOC, Technical Editor |HE progress being made in some of the color processes and the revival of interest in the talking pictures, especially those devoted to sound photography, have elicited the statement from many sources that "the next step forward is stereoscopic motion pictures," which will complete the system of reproducing, artificially, all of the elements of dramatic art, i.e., speech, action, form, color and solidity. This discussion is not intended as an exposition of the theory of stereoscopy because the subject is familiar to most of the scientific staff of the picture business. It has been suggested, however, that this society might well go on record in establishing a few facts for the benefit of those who might hold too lightly a serious problem, or who still cherish the idea of some system for producing stereoscopic motion pictures, that might be acceptable to the public. Nor is it our wish to deny the possibility of what we call a practical solution of the problem, for the mind of man has achieved such wonderful things, especially in the last fifty years, that the student hesitates to place a limit upon its accomplishments. We observe a growing confidence in the endorsement, by this body, of any idea designed to improve our art, and it is for this reason that we call attention to various experiments that have been misunderstood or misrepresented. The study of stereoscopy antedates, by many years, even the art of photography. Leonardo da Vinci selected from the common observation of this phenomenon two well defined elements in the art of picture making: those of stereoscopy and perspective. Theretofore, these two subjects were merely matters of curious interest to the more observant minds, but da Vinci made a deep study of them and deduced them to rules and laws sufficiently well grounded to place them among the arts and sciences. Also important was his observation of the effect of pseudo stereoscopy, i.e., in viewing a picture with one eye, placing the eye in, as nearly as possible, the actual point of sight. This discovery was so important that at the present day artists delight in viewing well rounded pictures or photographs from this "point of sight." Errors of draughtsmanship, camera set-ups and the focal length of lenses are often traceable to a lack of appreciation of this simple but important expedient. The word Stereoscopy is derived from the Greek, Stereos, meaning solidity and relief, but the following classification of the numerous elements associated with the phenomenon suggests its inadequacy. First. Perspective: the apparent diminishing of the size of objects, the converging of parallel lines to the socalled "vanishing point." This branch of art has furnished such a beautiful application of mathematics that infallible calculations may be made of the distance of objects from the point of sight, their relative distance from each other and their dimensions. Second. Common experience: dating from the conscious period of babyhood and by which we measure distances by judging the juxtaposition of objects and the overlapping of each other in the field of vision. This is one of the earliest provisions of nature for self-preservation, by enabling us to determine the nearness or remoteness of elements of danger, and also in the performance of manual labor. Third. The physiological construction of the eye: a complicated system of mechanics that excites a reverence for the provisions of nature. Fourth: The mental reaction to this physiological stimulus: a subject that awes the most learned. These various elements combine to produce the phenomenon, stereoscopy, which, in turn, is divided into several degrees. A. Complete Stereoscopy : the full effects of binocular vision among individuals possessed of a high degree of development of the physiological requirements and a perfect mental reaction. B. Pseudo Stereoscopy: the limits of monocular vision, or even individual deficiency in binocular vision, and various effects produced in monolens pictures. C. Direct Stereoscopy: by which we measure the dimensions of a single object, its form, etc., independent of its surroundings. D. Indirect Stereoscopy: by which we determine the dimensions, forms and relative distances by comparison with their surroundings. This is due to the unconscious appreciation of associated object outside of the so-called "yellow spot," when focusing on a given field. Indeed, it is questionable whether there should be such a classification as direct stereoscopy, for the oscillation of the orb is such an involuntary, independent agency, and the scope of the yellow spot is so great that in viewing even a tiny spot against an absolutely neutral background it is difficult to maintain a fixed point of sight. This directness is supposed to be maintained in proportion as we limit the field of vision, but the gaze is very obstinate when an effort is made to keep it on so small a point as a pencil dot. Even when studying a sphere against a black background, the supposedly ideal example of direct vision, the gaze shifts from one area of the surface to another and keeps up a continual process of comparison by indirection. A review of this very limited consideration of the ele(Turn to Page 26) Please mention The International Photographer when corresponding with advertisers.