International projectionist (Jan-Dec 1939)

merely claimed to give an illusion of roundness to the edges of objects. The other I have had no time to investigate. The statements of the inventor, however, as quoted by the press, contained nothing which raised in me the slightest hope that a way out of the impasse had been found. Stereoscopic photography may be divided into two types: the observation of still pictures by a single individual, and the observation of projected pictures by a group of simultaneous observers. In the early days, still stereographs were extremely popular. Our grandparents almost invariably had a hand stereoscope together with a set of pictures, generally a trip around the world. The problems of projection and simultaneous viewing may be considered the problems of three-dimensional movies. The only such movies yet shown publicly have been those using red-and-green spectacles. These are known as anaglyphs. Instead of being black and white, the two necessary pictures are respectively red-and-white and green-and-white. To the eye covered by the green lens the red-and-white picture appears black-and-green, since the red light fails to penetrate the lens and the white light gets through as green. To this same eye the green-and-white picture appears entirely green and consequently ceases to exist as a picture. The reverse is true for the other eye. Consequently the two pictures are rendered mutually exclusive to the eyes. The green-and-red areas fuse and are interpreted as white because of the complementary effect of the colors. This system has a number of defects. Since green and red are used to produce a black-and-white picture, colored movies are ruled out. Furthermore a dark object in the foreground placed against a white background obscures different areas of the background. Consequently the white area which is visible to only one eye continues to appear the color of the lens before that eye. The fused image of the object is therefore fringed by red on one side and green on the other. Finally, this kind of stereoscopic movie imposes an eye strain which frequently causes a very severe headache if the pictures are watched much longer than 15 or 20 minutes. • Polaroid Best Bet The newest and by far the best projection system involves the use of polaroid, a material which polarizes light. The bght projecting one pic ture is polarized vertically while that of the other is polarized horizontally. A pair of ordinary spectacles with similarly polarizing lenses is worn. The eye with the vertically polarizing lens sees only the vertically polarized pictures and vice versa. The difficulties in this method center around the problem of obtaining a light source sufficiently powerful to overcome the great reduction of intensity produced by polarization. Highpowered lights produce such high temperatures that the cooling of projectors becomes a problem. This is a difficulty, however, which is rapidly being conquered, and the method presents no other major obstacle. Very excellent three-dimensional movies have already been made with it and I have very little doubt that this is the method that will ultimately be used. In facing the problem of three-dimensional movies, then, the motion picture industry must first of all consider the matter of spectacles. Either the theatres must furnish each individual with the necessary device or they must expect the public to own it. I believe it will be impossible for a theatre to re-use the same spectacles continually. The cost of such glasses must be reduced to a nominal sum, say ten cents. A moviegoer may then own his own; if he forgets to bring them, he may purchase a new pair at the box-office for a dime. Many other systems for the showing of three-dimensional movies are possible. A half dozen different methods of using mirrors have been suggested. But they are cumbersome approaches to the problem because mirrors are rather fragile and easily dimmed. Reflecting surfaces, it seems to me, stand little show of surviving in this field. • Theatre, Studio Bequisites The next considerations are those of initial expense. Theatres will need two single projectors or a double projector plus screens that will not depolarize light. Changes in theatre shape will also be desirable. There is only one theoretically correct position from which to view a stereograph. Any movie viewed from too far to one side makes the characters appear extremely thin. The same effect, greatly exaggerated, or rather, more forcibly brought to the observer's notice, will be produced by three-dimensional movies. Furthermore, to an observer ir the back of the house the depth will be exaggerated; whereas to one in the front row the depth will be foreshortened. Though existing theatres will unquestionably continue to be used, the new ones will probably be rather long and narrow, since the distortions from the side are much more annoying than those from front to back. The added costs also extend into the studio. Many of the devices now employed to reduce expenses will have to be scrapped. Obviously, for instance, painted or photographic backdrops must be abandoned, for the lack of depth will immediately be apparent. The use of background projection screens, a very common device, will become enormously complicated. The very common picture, for example, of people riding on a bus or in a taxi, with the street scenes moving past, is now being filmed by holding the people still while the action on the street is projected on a screen behind them. In three-dimensional movies, the image on the projection screen will also have to be three-dimensional, properly polarized, adjusted to the proper depth to fit the required scene and of sufficient intensity to appear real. For the same reason the extensive film libraries of general scenes, such as those of war or crowds, which are now inserted to heighten a desired effect will have to be entirely rebuilt. It is interesting to speculate what effect three-dimensional pictures will have on the present crop of stars. Many an actress who is two-dimensionally photogenic may find herself three-dimensionally quite unacceptable, and vice versa. Probably a normally beautiful girl will appear just as beautiful in the new movies, and her public will not run the risk of being disappointed on seeing her in person as they now are. • Cost the Prime Factor It is apparent that all the real difficulties hinge on costs. But as with every other scientific advance, these expenses will diminish as production goes up and as inventive minds set about solving the problem of reducing them. In the early stages of the new movies the more spectacular effects will be emphasized. Moving objects which can be made to approach within a few inches of the observer will leap from the screen and audiences will scream and duck from them. Shots of autos or tanks apparently running over the cameraman can be made terrifyingly effective. The observer, forgetting that he is watching a picture, will be certain that he is in imminent danger of death. By altering the distance between the lenses of the camera and by utilizing the proper relationships of focal (Foot of Col. 1, next page) 20 INTERNATIONAL PROJECTIONIST