Patent GB-873118-A (GB)
Title: Improvements in or relating to an apparatus for taking in sections motion picture images on a corresponding number of films for subsequent mosaic combining as by film projection
Inventor: SMITH PHILIP STANLEY
IPC: G03B37/04
Filed: 1957-12-09
Abstract: 873,118. Kinematographic apparatus. FOREIGN DIETERICH CORPORATION. Dec. 9, 1957, No. 38232/57. Class 97(1) Apparatus for mosaic kinematography comprises two camera members each having a vari-focal lens system; a rotatable shutter which sweeps past the exposure aperture in an arcuate path, a film feed mechanism, and a drive shaft from which the film feed and shutter are driven in fixed time relation to one another, each camera member having an angle of view less than the angle subtended by the whole field to be recorded, the camera members being disposed with their optical axes in a common plane and at such angles to one another as to cover the whole scene to be recorded of which one camera member records one section of the scene and the other records adjacent sections such that the respective edges of adjoining fields of view are recorded in register. In this apparatus there are provided two synchronously driven power shafts operatively connected to the drive shafts of the camera members to drive the shutters in respective directions that, with respect to any object crossing or intersected at the adjoining edges of the scene sections, the arcuate paths of movement of the leading edges of the two shutters across the respective adjoining edges of the scene sections and across the respective adjoining components of the object so crossing or intersected are in the same direction, the operative connections also including'means for relatively setting the rotational angular relation between the shutters of the adjacent camera members to bring the leading edge of one shutter in phase with the edge of the other shutter so as to effect simultaneous image recording of the respective components of the object so crossing or intersected at the adjoining edges of the corresponding scene sections. As shown in Fig. 2, three lens systems L1, L2 and L3 are mounted on a base 30 which is completely hooded apart from the front rectangular aperture, the size of which is adjustable by panels 41, 42. The lenses have respective image planes Fl, F2 and F3 at which are recorded on photographic film, parts of a scene subtending angles A1, A2 and A3 of which A1 and A3 are reflected to the respective lens systems by mirrors M1 and M3, whilst the middle section is recorded directly. Thin vanes V1, V3 demarcate the respective boundaries between the image sectors and associated with each lens system are kinematograph camera members C1, C2 and C3 having film advancing devices, shutters and film take-up and feed spools in known manner, The mirrors M1, M3 are of identical construction and have their vertical edges adjacent the field of view tapering to sharp knife edges; the mirrors are adjustably held in C-shaped frames H1 (Fig. 9) having adjustable ball surfaces B1, B2 contacting their edge surfaces at several points. The light blocking vanes V1 V3 are of thin metal foil and are also adjustably held in C-shaped frames in vertical planes coincident with those of the tapering back surfaces of the mirrors and are maintained stretched tight by hand-operated winches in the upper links of the frame members. Each lens system (Fig. 18) comprises four components A, B, C and D of which B only is movable, the image plane being indicated at F. A diaphragm having leaves 151 is operable by a pin and slot connection 152 in known manner. The movable lens B rests in a carrier 160'held by a non-magnetic retaining ring 161, and the outside of the carrier 160 forms a seating for a resilient annular member 170, whilst a thin annular extension carries wire windings 163 and passes between the pole pieces 146b, 144k, of a strong permanent magnet such that, when the windings are energised, the lens is caused to move axially with consequent variation of focus, whilst the size of the in focus and out of focus images at the image plane remains constant to preserve register of adjacent images in the mosaic. To move the lenses B of each lens system synchronously and by equal amounts, an electrical circuit is provided with potential dividers for " zeroing " each lens, together with a single potentiometer for energising the three windings equally to cause equal movements; the windings may be energised with alternating current to cause the lenses B to oscillate about a mean position, or direct current for causing shift of the lens positions; furthermore, energisation with an alternating current superimposed upon a direct current provides for oscillation about variable mean positions. Due to the optical action of the sharp edges of the mirrors M, the boundaries of the image sections on the films overlap slightly with diminishing intensity as in the strips GR1, GR21 (Fig. 20c) such that during subsequent projection for forming the whole image of the scene, these strips overlap to provide continuous and uniform intensity; the extent of overlap depends upon the aperture setting, and the camera members may be pivotally mounted for variation of the overlap. Each camera casing comprises a rotatable disc shutter 250 (Fig. 6) opposite an aperture plate 258 and carried on a shaft 251; a film pull down arm 254 is actuated by a cam 255 on a shaft 253 and a register pin mechanism 256 is driven by a cam 257 on the shaft 253 such that when the film is instantaneously stationary for exposure, a pressure plate (not shown) holds the film in the desired position. The shafts 253 of the three cameras are driven in phase with one another. To ensure that the overlapping regions of each of the two adjoining fields of view are recorded at the same instance, the shutters are caused to rotate in the same direction since adjacent sections are mirror inverted with respect to one another. Angular adjustment of the shutter of each camera with respect to its power shaft is effected by means of a gear 269, Fig. 7, engaging the driven shaft 240 and a gear 268, Fig. 6, driving the shaft 253. Gear 269 is slidable in its housing 266 either to rotate the gear 268 relative to the driving shaft 240 whilst still engaged with that shaft, or to become disengaged from shaft 240 to allow shaft 253 to be manually rotated relative thereto.