Patent GB-523293-A (GB)
Title: Improvements in or relating to a viewing device for motion picture cameras
IPC: G03B19/18
Filed: 1939-04-14
Abstract: 523,293. Kinematograph cameras. KODAK, Ltd. April 14, 1939, No. 11335. Convention date, April 16, 1938. [Class 97 (i)] A viewing device for detachable insertion in the magazine chamber of a kinematograph camera comprises a body having locating surfaces by which it is accurately positioned in the camera and carrying the optical system. In the form shown, the device comprises a frame 80 having a central channel formed by walls 81 in which the optical elements are carried and extensions 82, 84 on which are formed locating surfaces 83, 85. When the device is inserted in the camera as shown in Fig. 1, these surfaces are engaged by the locating members, for example, those shown at 27 in Fig. 2, which serve to position the film magazine in the camera. The device is positioned laterally by locating members 86, Fig. 1, which engage bosses 28 on the cover plate 23 of the driving mechanism, and it is engaged by the springs 29, 29' which also position the film magazine when this is inserted. The channel formed by the walls 81 is covered by a plate 95 including a front plate 96, in which is formed an aperture 97 and which carries a locating member 98. The optical system comprises a positive lens 87 having a ground plane surface 88 which is located in the image plane, a pair of mirrors 89 for displacing the path of the image, a lens 90, and front and rear ocular elements 93, 94. The lens 90 is carried by a slide so that it may be moved by a finger-piece 91' from a position in which the whole field of view is covered to one in which a highly-magnified portion of the image is seen for focussing purposes. The camera shown is provided with means, similar to those described in Specification 469,950, for preventing operation of the mechanism when it is open. These means comprise a projection 76, Fig. 5, on the slidable latching bar 71 which, when the bar is moved forwardly to release the cover 16 of the camera, engages the top of an arm 77 carried by a vertically movable locking member 64 which has at the lower end a projection 70 engaging a single-toothed cam 63 on the claw-operating shaft 61, thereby preventing operation of the mechanism. A tooth 79, Fig. 5, on the latching bar 71 engages in an aperture in a spring 78 in the forward position of the latch, which cannot therefore normally be moved back to allow the locking-member 64 to be raised, so starting the mechanism, until the cover 16 has been closed, when a taper pin (not shown) on the cover engages the spring 78 and causes it to release the tooth 79. As, however, the cover cannot be closed when the viewing device is in position, whilst it is at the same time necessary that the mechanism should be operable to open the shutter, the viewing device carries a tapered pin with a head 107 which, after withdrawal from the device, may be inserted into the U-shaped end of the spring 78 to disengage it from the tooth 79. The latch 71 may then be moved back, thereby releasing the locking-member 64 so that it may be raised to start the mechanism through an arm 68 on a rock-shaft 67 operated by the trigger 66. The movement of the mechanism is automatically stopped, with the shutter in the open position, when the claw 59, which lies in a recess 103 in the front face of the viewing device, is arrested by an abutment 104. The conical shutter 52 is carried by a shaft 54 rotatably mounted on the socket of the objective, and is driven through bevel gears, together with the shaft 61 operating the claw 59 and a shaft 47 carrying the take-up clutch 48, by two spring motors 30 simultaneously wound by a gear 43 on the winding shaft 44.