Patent GB-629598-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B19/04
Filed: 1946-06-12
Abstract: 629,598. Photogrophic roll-film cameras. PALMER, W. J. GRAHAM-. June 12, 1946, Nos. 17657 and 38177. [Class 98 (i)] In a photographic camera for 35 mm. or smaller film, the optical elements of a directvision viewfinder and the camera lens are carried by a mount which, for focusing purposes, is movable towards and away from the focal plane, the optical axis of the lens and the viewfinder being maintained parallel to the axis of the camera by the co-operation of bearing- surfaces on the case with a part of the mount and with a tubular guide to which the mount is attached and from which it is separable as a unit. The view-finder may slide in a slot in the case. The mount may carry focusing calibration marks (preferably on the viewfinder housing), a rotatable aperture plate, and the shutter mechanism. The case may be in two parts with a light-tight joint between them, and the top of the case may be thick enough to accommodate the film-winding knobs. As shown in Fig. 4, the camera body has a front part 10 and a back part 12 fitting together, which may have interengaging grooves and tongues on their longer edges and may be diecast. The lens 27 is mounted in a disc 26 mounted on a tube 22 sliding in the camera body and flanged to prevent complete withdrawal. The flanges may have flats to prevent rotation. The viewfinder mount 28, Fig. 2, is fixed to the disc 26 and slides in a slot provided in the front or both parts of the case. A scale 38 on the lens mount, preferably on the top of the viewfinder mount, is read in conjunction with a mark on the case, or the edge of the viewfinder slot. A disc 42, rotating in a recess in the disc 26 about a pivot 46, has apertures 44 of different sizes to vary the diaphragm stop of the lens. It is turned by its edge, part of which protrudes beyond the disc 26, and held in position by a spring 48 clicking into depressions 47. The stop in use is preferably indicated by marks seen through an aperture in the disc 26. The shutter is mounted in a box between the disc 26 and the tube 22, and is of the kind having a plate 60, Fig. 7, pivoted on the disc 26 at 64 to swing across the lens aperture, the exposure being made through a slot 62 in the plate 60. A trigger 77 with an arm 74 carrying a pin 66, to which is connected a hair-spring 72 also connected to plate 60, rocks in both directions on a pivot 75 to effect the movement of plate 60. For a time exposure, a spring-loaded pin 80 is depressed into the path of a detent 78 on plate 60, which is thereby arrested on operation of the trigger 77 with the flat 62 in register with the lens until fin 80 is released. When the lens mount is pushed back, the bent-over end of trigger 77 enters one of two holes 79 in the case, preventing accidental operation. The winding knobs 86, 88 are recessed in the top of the case. One has ratchet teeth, preferably on the lower or an inner surface, co-operating with a pawl. The second Provisional Specification refers to : (1) spring clicks (e.g. balls urged into recesses) co-operating with the viewfinder to hold the lens mount in position at various focusing distances; (2) spring clicks holding the two halves of the body together; (3) a cam operated by the winding-off knob to separate the parts of the case.