Patent GB-704415-A (GB)
Title: Finished lenticulated film and process for producing the photographic recording thereon
IPC: G03C7/14
Filed: 1951-11-09
Abstract: 704,415. Lenticular film records. GRETENER, E. Nov. 9, 1951 [Nov. 10, 1950; July 14, 1951], No. 26347/51. Class 98(2) Finished lenticulated photographic film including at least two interlaced separate records is produced by exposing for each record, through a light filter of regularly varied transparency and through the lenticular raster and the film, a photographicallysensitive layer of high gamma whereby the record made behind each lenticule comprises a transparent area on an opaque ground, the size of the transparent area being proportional to the mean brightness of the corresponding portion of the original. The filter may increase in density uniformly from the edges towards the centre so that the transparent area is proportional to the square of the orightness of the original, or it may be in the form of strips of fixed width which increase in density only along their length so that the transparent area is linearly proportional to the brightness of the original. To ensure that the separate records do not overlap, the filters may have transparent strips along their upper and lower margins so that the corresponding areas of the film are opaque. As an alternative, transparent rods illuminated from their end faces may be disposed between the filters to produce these record-separating strips. As described, the invention is applied to producing coloured motion picture films intended for projection, which may be of the doubly lenticulated kind described and claimed in Specification 682,853, by printing from colour separation records. The records 35 may be printed simultaneously by projection each image being projected to the same film frame along the appropriate directed to produce separate interlaced records by a pair of spaced lenses 39 between which is disposed the light filter 41. The film may have either spherical or cylindrical lenticulations. In the latter case an auxiliary perforated strip 102 having lenticulations crossing those of the film 100 at 90 degrees may be employed during recording and the film and strip may be held in close contact by exhausting air from between them by ducts in the stationary member of the picture gate in register with the film perforations connected to a pump. In the case of contact printing, the light source and filter may be successively positioned in their appropriate positions so as to print the component records in turn, while if three components are all on a single film, the light source filter and original may be displaced after each exposure and the recording film after only every third exposure by automatic means. Alternatively separate sources and filters may be used for printing each component whether these are on a single or separate films. In the case of cylindrically lenticulated films, a strip similar to the strip 100 may be inserted between the negative and the recording film, but preferably the image-bearing face of the negative is itself cylindrically lenticulated after it has been exposed. Stereoscopic and colour stereoscopic films may be produced by the same methods.