Patent GB-1528362-A (GB)
Title: Stereoscopic photography methods and apparatus
IPC: G02B30/27
Filed: 1975-09-15
Abstract: 1528362 Stereoscopic photography DIMENSIONAL DEVELOPMENT CORP 15 Sept 1975 [24 Sept 1974] 37757/75 Heading G2A In a system for producing stereoscopic pictures, N views of an object field are recorded by a camera having N equispaced lenses, the inter-lens spacing being adjustable according to the distance between the lenses and a selected element of the object field, the images of these views subsequently being projected through N projection lenses on to a photosensitive surface positioned behind a lenticular screen. As shown, the camera 96 is focused on a key subject matter element K 1 , at a distance k 1  from the objective plane 94, the four objectives 98, 100, 102, 104 occupying the positions shown in solid line, and producing sharply focused images K', on the film frames 106, 108, 110, 112. The objectives are spaced apart a distance T 1  and the images on the film frames spaced apart a distance D. The enlarging or projection lenses 114, 116, 118, 120 are spaced apart a distance d, so that the lineiform images K" 1  are formed evenly over the whole width w of a lenticule 124 of the lenticular film 126, the various parameters having specified mathematical relationships. In order that the area beneath each lenticule is completely filled with lineiform images, of uniform intensity and free from appreciable overlapping, so that a non-interrupted picture is seen by the observer, the area is scanned during projection of the image. That is, the angle of incidence of the projected rays is progressively changed during projection. Figs. (not shown) 10A, 10B, 10C are mechanical arrangements for effecting various types of scanning movement. If, instead of focusing on the element K 1 , the camera is now focused on an element K2, at a distance k2 from plane 94, the objectives 98-104 will have to move a distance #e from plane 94, to the positions shown in broken line, in order to bring the images K 2 of the element K 2  into focus on film plane 127. At the same time the spacing between the lenses must be changed from T 1  to T 2  as shown in the left hand side of Fig. 4, the relationships between the parameters again being derived mathematically. Fig. 5 shows a practical realisation of a suitable camera 132 having five objectives 134, 136, 138, 140, 142. The five exposures may be made simultaneously or consecutively. The lenses are mounted in blocks which can be moved in the plane of the lenses, for varying the inter-lens spacing, and also axially, for focusing purposes. Such movements are controlled by a series of cams actuated by a threaded rod 180 having an operating knob 182. Thus operation of knob 182 causes the objectives to move both laterally and axially to maintain the desired image positions on the film plane in accordance with mathematically derived relationships. Rod 180 can be linked to the movable element of a coincidence-type rangefinder-viewfinder. Fig. 7 (not shown) is a simpler form of camera having only fixed-focus lenses. Instead of a multi-lens projection system a single projection lens may be used (218), Figs. 8 and 9 (not shown), the lens itself and the film strip carrier being moved into successive positions for recording the lineiform images. A single-lens camera may also be used to take a sequence of pictures by moving the camera along a straight path transverse to the object field.