Patent GB-798038-A (GB)
Title: Improvements relating to photographic cameras with interchangeable lens systems
IPC: G03B7/00
Filed: 1956-01-02
Abstract: 798,038. Photographic cameras. DECKEL, H., and DECKEL, F. W. Jan. 2, 1956 [Jan. 11, 1955; Feb. 1, 1955; Feb. 1, 1955; Feb. 1, 1955; Feb. 1, 1955], No. 45/56. Class 98(1) In a photographic camera with an interchangeable lens system and an independent shutter speed setting element mounted on the camera body, the lens system includes a diaphragm aperture setting device, focusing means, a depth-of-focus indicating device with pointers movable over the focusing scale, and means for coupling the shutter speed setting element with the diaphragm aperture setting device when attaching the lens system to the camera. As shown, a bayonet ring 60 is mounted on the front plate 64 of the camera, and the housing 72 of the shutter is bolted to the bayonet ring. The mechanism of the shutter is not shown, except the timing ring 80, which has a lug 86 passing through a slot 88 in the bayonet ring and engaging a setting ring 82, which is retained for rotation adjacent the bayonet ring by a packing ring 90. The lens mount, which is made in two parts 92, 93, has lugs 94 engaging the bayonet ring, and has a focusing ring 100 threaded therein. A bush 106 is axially connected to the threaded portion 102 of the focusing ring 100, but is restrained from rotation. The bush 106 carries the front components 120, 122 of the lens. The iris diaphragm 132 is housed between bush 106 and a ring 114 attached thereto. The diaphragm adjusting ring 134 is connected by a pin 136 to a ring 30 of a depth-of-focus indicating device which consists of rings 30, 50 and the components between them and which is of the kind described in Specification 785,857. Two pointers 10, 12 actuated by the mechanism indicate the depth of focus on the focusing scale 14. A coupling ring 140 rotatably mounted between the parts 92, 93 of the mount has an arm 142 projecting between the parts and engaging a lug 32 on the ring 30, so that the diaphragm aperture and the depth of focus indicator may be adjusted simultaneously by means of ring 140. When the lens mount is inserted in the bayonet joint, a tooth 148 on the ring 140 engage one of a set of notches 150 on the front edge of the exposure time setting ring 82. Ring 140 is axially loaded by a corrugated spring 152 which keeps tooth 148 in engagement with the notch. The ring may be retracted against action of spring 152 for adjusting the relative positions of rings 140, 82. This adjustment is facilitated by a mark on ring 140 co-operating with a scale of light values on ring 82, or by scales of diaphragm apertures and shutter speeds on rings 140, 82 respectively. Modifications are described in which the depth of focus indicator is mounted on the camera body and (1) the front component of the lens has a screwed focusing mount: (2) the lens mount, which moves axially for focusing, carries the iris diaphragm; or (3) the focusing ring is rotatable without moving axially. Further, the stop setting element may be mounted on the camera body and the depth of focus indicator may be carried by the axially movable lens mount, and the depth of focus indicator may be of a kind other than that specifically described. Specifications 763,154 769,070, 769,081, 770,819 and 782,539 also are referred to.