Journal of the Society of Motion Picture and Television Engineers (1950-1954)

image-compensating tyjx* cameras, produce images of the highest possible resolution. Rotating-prism cameras have been manufactured and used extensively in the 8mm, double-width 8mm, 16mm, and half-frame height 35mm frame sizes. They all have one deficiency, and that is that no satisfactory enlargements can be made on full-frame 35mm film for large-screen projection. On a 16mm film which had 50-lines/min resolution, a 35mm enlargement from the 16mm film has only 20 lines/mm, which does not give good results when projected when compared with films taken on an intermittent camera. The film capacity of the commercially available cameras was too small, also. Longer runs were desired. Realizing the need for a 35mm large capacity high-speed camera, the Government of the U.S.S.R. requested the Western Electric Company to design and build such a camera in 1945. In an earlier paper,* certain suggested improvements of design were discussed. The first of these was prism design, and second, the design of the sprocket. The full-frame 35mm Fastax now being introduced has the experience of eighteen years of rotating-prism cameras behind it. The design features and specifications of the new camera are as follows: Camera Housing: To reduce weight, a magnesium-aluminum casting will be used. It will be heavy enough to withstant high-blast pressures. Parts will be mounted to withstand at least 20 "g" acceleration. The camera housing will enclose the drive mechanism and lens mount, and will be fitted with standard motion-picture threads for mounting on standard motion-picture tripods. * John H. Waddell, "Design of rotating prisms for cameras," Jour. SMPEy 53: 496-501, Nov. 1949 (also in High-Speed Photography, vol. 2). Sprocket: A sprocket of approximately 6-in. diameter is employed. The curvature of this sprocket face very nearly matches the change in back focus created by the oblique rays as they pass through the prism. Since 35mm negative and color stock in the United States is on slow-burning base, the sprocket is designed to take ASA standard negative perforations. A 180° wrap is used as has been the case on previous Fastax cameras. The sprocket is light in weight and is black to prevent halation and reflections from the inside of the sprocket through the viewing holes when an intensely bright selfincandescent subject is photographed. Film Capacity: 500-ft, special daylightloading spools have been designed to ensure maximum acceleration and to permit better balancing of the shifting load. The jump at the beginning and the end of the films is minimized. These spools are inclosed in detachable magazines. Each magazine comes supplied with a motor for the take-up. The film is used on spools so as to keep it in place under conditions of vibration and when high centrifugal force is present. Prism and Housing: The prism is made from Eastman Kodak 450 glass and is four-sided. The housing is very much heavier than on any previous Fastax cameras. It, too, is designed to provide better chopping action of the image. The prism housing is supported by an outboard bearing to make the pictures more steady. The half-frame 35mmFastax employs the same method, and that camera has been noted for its steadiness. There is no provision for removing the prism for oscilloscopic purposes, for it has been found that, with the very tight tolerances of fits and adjustment of gears, jumping pictures result from removing the prism housing. Waddell: 35mm Camera 625