Improvements in or relating to the taking of photographs of a scene against an illuminated background

摘要

564,532. Photographic studio backgrounds; composite photographs. BROOKES, N. E. (Technicolor Motion-Picture Corporation). July 20, 1943, No. 11796. [Class 98 (ii)] In a method of taking a scene placed in front of a transparent backing, the rear of the backing is illuminated with diffused light of substantially uniformly distributed flux, and the backing is provided with means which causes it to emit from its front surface facing the camera a plurality of beams, each of which is of uniform flux density, has its axis parallel to the axis of the camera, and subtends at the backing an angle which is at least as large as, and is preferably equal to, that subtended at the aperture of the camera by the longest dimension (usually the diagonal) of the photographically effective emulsion area in the camera. The invention may be applied to the method of making composite kinematograph colour films described in Specification 538,628, wherein a foreground action is photographed against a plain backing of a colour not recorded when making at least one of the component colour records it ensures that the light flux reaching the camera from the backing is the same for all points of the backing, and also that stray light from the backing, reflected by the foreground objects into the camera, is reduced to a minimum. Fig. 2 shows the set-up, wherein a foreground action F is to be photographed, by a camera C, against a plain backing comprising a coloured diffusing screen D, illuminated as uniformly as -possible from the rear by lamps L with reflectors, and having in front of it at a short distance o a screen S consisting of small lenses E, each of which emits towards the front a beam having the aforementioned characteristics. The screen S may consist of a glass plate 2, Fig. 5, the front surface of which is covered by contiguous small glass spheres 1 secured to it by Canada Balsam 3; or hemispherical elements may be formed by moulding or impression in the surface of a plastic sheet as of cellulose acetate. Other forms of screen are described in which the lens elements are replaced by a grid of short tubes, or a system of light-conducting rods connected together by black cement, with their axes perpendicular to the plane of the screen. The angular extent 0 of each beam leaving the backing depends on the relation between the dimensions of the elements and the distance o between screens D and S ; and if the elements are small enough, the distance o may be so small as to permit the screen D to be formed on the rear surface of the screen S.