GB472013A - Improvements in and relating to apparatus for taking and/or projecting continuously moving kinematographic films - Google Patents

Abstract

472,013. Kinematographic apparatus. PINTSCH AKT.-GES., J. Oct. 29, 1936, No. 29475. Convention date, Oct. 31, 1935. [Class 97 (i)] Optical compensation for a continuously moving film is effected by a rotating regular polyhedral prism having a thickness s satisfying approximately the equation s =uz/2#-b/n-1 where n is the distance in centimetres between consecutive picture frames, z is the number of faces of the prism and u the refractive index of the prism. The film 11 is illuminated by parallel light from a source 9 and condenser 10, compensation being effected by the prism 12. The source 9 may be displaced from the axis of the condenser to illuminate the film by reflection. The prism 12 and the sprocket for the film 11 may be on the same shaft 13, the film either being deflected by rollers or the light beam may be reflected by prisms to pass through the prism 11 after passage through the film. To minimize the errors in compensation which occur when a corner of the prism passes the film the light from the lamp 9 may be reduced in intensity at that time by a suitable electrical mechanism and, in photographing, the light illuminating the object may be reduced in intensity at the moments of inexact compensation. Alternatively a screen may rotate in front of the lamp to shut-off the light when compensation is inexact or the corners of the prism 12, Fig. 5, may be ground plane at 20, 21 .. and blackened.