The Cine Technician (1953-1956)

54 THE CINE-TECHNICIAN May-June, 1953 PRACTICAL TECHNIQUES FOR 3-D AND WIDE SCREEN FILMING by Charles G. Clarke, A.S.C. President, American Society of Cinematoyraphers \ LTHOUGH various methods for wide-screen and -*-* three-dimensional motion pictures have been tried out on an experimental basis since the inception of the cinema, no concerted effort has been attempted by the industry to introduce this advancement for general exhibition until now. As progress from black-and-white to colour photography followed a slow process of development, the next step towards reality on the screen — pictures with natural depth — has likewise long been delayed. This has been partly due to a reluctance to attempt something new so long as the old was acceptable, and partly because of the radical adjustments necessary on the part of the spectator as well as the producer to make these new techniques possible. It is unnecessary here to go into the theory of binocular vision and depth perception. We all know that every person having normal vision sees depth because each eye sees a scene from a slightly different angle than the other. This angle, however, is all-important. With the average person the eye separation or interocular distance is 2\ inches or about 64 millimetres. For natural reproduction by photographic means it is therefore imperative that the lenses of 3-D cameras making the left and right hand pictures be spaced no more nor less than this normal separation. Any violation of this rule of nature will result in false perspective and unnatural results on the screen. True, in certain special effects, the interocular separation will have to be varied; but for normal scenes the camera lenses should be properly spaced. Unfortunately, there have been camera installations which have violated this rule. The 1,000-foot film magazine has forced the cameras apart when they have been set up to face each other with reflecting mirrors between them. When used in this way with wide angle lenses, elongation of the subjects and over-drawn depth perspective result. The cameras must be accurately mounted so that each one records an identical image as to size, alignment and synchronisation of picture to the other. As the human eyes constantly " toe in " or converge as they look at various objects in different planes of depth, so must the cameras be equipped to converge on the principal object of interest. Presuming that the cameras to be used fulfil these basic requirements, what are some of the practical filming techniques that must be observed? As literature on this subject is almost non-existent, perhaps the observations of some years of my experience in this field will be of assistance. While there are no great mysteries connected with three-dimensional photography, basic rules do apply, and to a certain extent we must learn to undo some of the things we have been doing in flat photography all these years in an attempt to simulate third dimension. In the past we have been using very wide angle lenses, backlighting, and silhouette foreground objects to give the illusion of depth to planar pictures. We have been forcing and even over-drawing perspective with the 25mm. lens. Commonsense, therefore, dictates that with true three-dimensional filming these illusions are not only unnecessary but can be detrimental. Except for special effects, the normal long shot in 3-D is best reproduced by no shorter focal length lens than the 40mm. The 50mm. is ideal for medium shots and the three-inch lens is excellent for closeups. For long shots some tolerance is allowable in excess interocular spacing, but for close-ups, even with the three-inch lens, the lens spacing must not exceed 2\ inches for natural reproduction. Some readers may recall that in the very early days of film making it was a hard and fast rule that the feet of the actor must always be shown. Audiences had to see what the characters were standing on! This seems ridiculous now that we are educated to seeing close-ups with no visible means of support; but it took many years to get audiences adjusted to this technique of the cinema. Likewise, it will take some time before audiences will accept persons or objects standing out in front of the screen in 3-D films, where in reality they belong. In time this will come about of course, but for the present it is probably better not to include objects too close to the foreground or ahead of convergence. Branches of trees, foreground lamps and such had best be left out or moved back into the scene for the time being. Likewise spectators are not yet accustomed to seeing objects out over the audience, so the projectors will be converged from infinity or " toed-in " to a middle foreground in order to push back the actors to the plane of the screen. Distant objects behind them will therefore appear " through the window " or in back of the screen. For this reason the screen becomes a window frame, and the composition of the scenes must be arranged so that the actors are completely within the frame. It is disturbing to cut on a shoulder or to have the hands of the players going in and out through the frame, which in 3-D has solidity. In three-dimension films, the eye scans the scene much more than in the flat picture. For this reason it is desirable to have as much definition and depth of focus as is possible. For the same reason excessive contrast and empty shadows place a hardship upon the spectator who automatically is trying to analyse every part of the picture. Much of the present technique can be retained in 3-D cinematography. Boom shots, pan shots, travel shots and such can be used to good advantage where provision for follow focus and lens conversion on the principal objects of interest is accommodated. As