GB366958A - Improvements in or relating to colour photography - Google Patents

Abstract

366,958. Colour photography and kinematography. BAKER, T. T., The Hut, Hatch End, Middlesex, and SPICERS, Ltd., 19, New Bridge Street, London. Nov. 7, 1930, No. 8666/31 (divided application), and 858/31. [Class 98 (ii).] In the reproduction of a master picture transparency, made on regular or irregular pattern multicolour-screen sensitive material, by projection-printing upon similar sensitive material, an image of the master picture is focused upon the emulsion of the copy film by means of a lens of wide aperture, such as F/2, and therefore of such critical focus that the image of the master colour screen, which is formed in the plane of the colour screen of the copy, is sufficiently diffused to avoid the production of interference effects such as the moire effect. These effects may be avoided more readily by the addition of a plane-parallel sheet of transparent singly-refracting material such as window glass or photographic negative glass, of thickness preferably between <3>/64" and #" and having plain faces, which is placed in the projection system either in front of or behind the wide aperture lens. The lens may comprise two similar components, each of aperture F/4 and of focal length 180 mm., separated by a distance of 2 cm., and it is provided with a micrometer focusing adjustment. Reference is made to reproduction with projecting lenses of aperture F/16 to F/32. Specifications 322,231, 322,432, 324,043, and 337,041, [all in Class 98 (ii), Photographic processes &c.], are referred to.