GB512733A - Improvements in or relating to photography in colour or in relief - Google Patents

Abstract

512,733. Colour photography. LASSUS ST. GENIES, H. H. J. DE. March 17, 1938, Nos. 8306 and 8307. Convention dates, March 19, 1937, and Feb. 23, 1938. [Class 98 (ii)] To remove traces of lines or spots in the projection or copying of images recorded on multicolour lined or lenticular material, an auxiliary optical system is arranged in or as closely as possible to the projecting objective, this system comprising at least two superposed lenses of short focal length, one positive and the other negative, the combination having a focal length which is very long compared with those of the individual lenses. As shown in Fig. 1, the superposed lenses L1, L2 are of glasses having slightly different refractive indices, and are placed adjacent to the diaphragm C of the projection objective O. Two such lens systems having resultant focal lengths of opposite sign may be juxtaposed, or the surface of separation of the lenses L1, L, may be curved as shown for example in Fig. 2 to produce two resultant focal lengths. In copying monochrome images from lenticular or multi-colour supports, three lens systems may be employed and a movable shutter used to prevent overlap of the individual images. The lenses are cylindrical. Specification 391,908 is referred to.