American cinematographer (Jan-Dec 1942)

Why Not Try Making THIRD DIMENSIONAL MOVIES? By PHIL TANNURA. A.S.C. IF you're one of the many amateurs who are looking for something new to take the place of pet locations or subjects that have landed on Uncle Sam's restricted list, why not try third-dimensional movie-making? Seeing your movies stand out in real, stereoscopic depth will give new life to even the most familiarly commonplace scenes. Suggesting that amateurs try making thii'd-dimensional movies when the professionals haven't done it yet on any really commercial scale seems fantastic, doesn't it? But it really isn't. Quite a few amateurs have already made successful stereo-movies in both 16mm. and •8mm., and in Kodachrome as well as black-and-white. In things like these, the amateur ideally has quite an advantage over the professional. The professional has to make sure that whatever he does can be applied on a commeixial scale. The amateur— lucky fellow! — doesn't have to worry about that so long as the idea doesn't run into a matter of too much expensive or unavailable equipment. In this case, it means that the amateur can make his third-dimensional movies by a method the professional has known about for a long time but couldn't use because of commercial complications that come up when you are showing the pictures to several hundred audiences a day. There's nothing particularly new about making third-dimensional photographs. The principle used today is basically the same one used in making the old-fashioned stereographs that graced every parlor whatnot back in the days when bustles and sideburns were in fashion. It works just as well for movies today, but we've got the necessity of working out a better method of viewing our movies than the old-time stereoscope afforded. We see depth because our eyes are a slight distance apart (the average separation is 2% inches), and each eye sees things from a slightly different angle. The right eye sees a little more of the right side of things than the left eye does, and vice versa. And our optico-nervous system is so arranged that each eye telegraphs its own picture to the brain, where the two slightly different images are blended into one thirddimensional one. All stereoscopic vision depends on this matter of two-eyed seeing; a man with one eye can't perceive depth at all. To get a thii'd-dimensional photograph, all that is necessary is to make two almost identical pictures of a scene through a pair of lenses that are spaced about the same distance apart as the average human eyes, and then to provide some method of viewing these pictures so that the right eye can only see the right-eye picture, and the left eye sees only the left-eye picture. Our brains will do the rest, blending the two into a single image with natural depth and roundness. Grandfather's stereoscope did this optically, putting a lens in front of each eye to focus it properly on the appropriate picture, and generally providing Dr. Ghrist's projection set-up for stereoscopic 8mm. Note viewing spectacles in foreground, and rigid base mounting. Two Cine-Specials mounted and interlocked for thirddimensional filming. a little plywood panel between the lenses to make sure the left eye didn't get a chance to peek over at the right-eye image. The occasional experimental threedimensional 3.5mm. movies, like the MGM-Pete Smith "Audioscopics" shortsubjects, did the same thing by a complementary-color filtering. The two necessary pictures were printed on a positive film with an emulsion on each side of the celluloid base. One emulsion was dyed red, and the other blue-green. Everyone in the audience had a little spectacle-like card through which to look at the pictures. Over one eye-hole in this card was a bit of red gelatin, which let the red image go through but completely filtered out the blue-green one, and over the other eye-hole was a bluegreen gelatin which kept the red image from passing through. The best system for amateur use, however, is to keep the two images always on separate films, and run them on two synchronized projectors with a polascreen over the lens of each projector. These pola-screens are "crossed," so that the light from one projector is polarized in one plane, and the light from the other is polarized in a plane at right angles to that of the first. The audience wears spectacles with similarly crossed pola-screen lenses, so that each eye can only see its proper image. The mechanics of making and showing stereo-movies by this method isn't so terribly complicated, but since it calls for two cameras and two projectors, probably the best way to handle it these days would be for two filmers to team up on it. The mechanical end of the problem will certainly be most easily handled if both cameras arc of the same make, and both jirojcctors also of the same make. The two cameras should be mounted on a base which not only holds them firmly aligned, but i)rovides a means for mechanically interlocking their mechanisms. Metal construction is naturally best for this base, but in these days of 362 August, 1942 American Cinematographer