International projectionist (Jan-Dec 1935)

BACKGROUND PROJECTION FOR PROCESS CINEMATOGRAPHY BACKGROUND projection for process photography now used extensively in all motion picture studios is more economical than the Dunning process, the color-separation method, the use of printing masks, and other arrangements. It is probably the simplest process that has yet been devised, and with proper care can produce satisfactory results. It consists in projecting a picture of the desired background, which has been photographed previously, upon a translucent screen, the foreground action of the picture taking place in front of the screen. The foreground objects are so lighted as to balance the screen illumination, and the whole is finally photographed as a composite scene. The most important factor involved in the background projection process is steadiness of the picture. To begin with, the negative film used for making the "plate" or "key", which are the names given to the scene to be projected, has to be very accurately perforated, and only fresh stock must be used. Eastman and Du Pont have both developed such an accurately perforated film, having a finer grain with a slightly lighter contrast than the regular negative emulsions, and having approximately the same camera characteristics as the regular Super-Sensitive Panchromatic negative. The camera used for shooting the plates must produce absolutely steady pictures. Its ability to do so depends upon the mechanism of the camera itself and the manner in which the camera operates. A standard Mitchell camera having a shutter opening of 170 degrees is used for making the plates, and its steadiness is carefully checked periodically to assure good results. The prints to be projected present a problem that has not as yet been solved satisfactorily. Due to pilot-pin registra G. G. Popovici tion in step printing, shrinkage of the developed negative causes some difficulty. If the pin is designed for the sprockethole of fresh positive stock, using the Bell & Howell perforation, during printing the negative sprocket-hole will be forced down upon the pin by a slight movement of the finished positive due to shrinkage. No matter how the pin is designed, so long as shrinkage is to be considered some difficulty will always exist. Only unshrinkable stock would be completely satisfactory for pilot-pin registration. Projection of the plate positive has successfully been accomplished in our studios. Contrary to West Coast procedure, we use a side-guided projector, designed by the International Projector Corp. To assure perfect steadiness, the gate and film-trap have been especially designed. The steel guide is hard and has been ground. The tension springs are carefully balanced to assure perfect side-guiding and proper gate pressure. The Geneva intermittent movement is selected for its precision, having no tolerances, and the intermittent sprocket is of the type recently approved by the S. M. P. E. and has also no tolerances. An ingenious device incorporated in FIGURE 1 Set-up of pro jector, camera, translucent screen, »««««s ^ lights and actors I r for rear projection process photography. [17] Generally regarded as the tail end of the motion picture process, projection has been playing an increasingly important role in the studios through the development of the 'process shot\ as background projection is known. That intriguing background seen in any number of current productions means not that the production unit travelled afar on a location trip but that the industry's technical workers have registered an important advance and projection has made another outstanding contribution to the progress of the art. The why, how and ivhat of this extremely interesting process, as originally presented before the S. M. P. E., is set forth in the accompanying article. — Editor. this projector enables the projectionist to check at any time the steadiness of the projected picture. Unsteady projection may be attributed to the print or to the projector. To be able to check one or the other at once, a cut-out is provided in the gate permitting an image of the edge of the running film and two sprocket holes to be projected upon the screen with the picture. If the image of the sprocket holes is steady and the picture image is unsteady, the print is obviously the cause of the unsteadiness. If the sprocket hole is unsteady, there still remains the question whether the projector is working properly, because instances have been found in which the film had shrunk unevenly, causing the sprocket holes to be unsteady. Such a test should always be made with fresh stock. (It is of vital importance that the projector always be kept clean, because an accumulation of dirt may cause unsteadiness of the projected image.) The advantages of this projector over those employing the claw movements are outstanding. This projector has a shut(Continued on page 26)