Patent GB-538080-A (GB)
Title: View finder control for photographic cameras
IPC: G03B19/18
Filed: 1940-06-21
Abstract: 538,080. Photographic view-finders. BROOKES, N. E. (Technicolor Motion Picture Corporation). June 21, 1940, No. 10698. [Classes 97 (i) and 98 (i)] A device for adjusting the axially and laterally movable optical system of the view finder of a camera contained in a housing comprises mechanism which is movable with the optical system of the finder and is connected by articulated link motion-transmitting means to controlling means mounted on the housing. In the form shown a kinematograph camera C is surrounded by a sound-proof housing 101 and is provided with a view finder of the kind described in Specification 538,744, part of which is mounted on the camera within the housing whilst a viewing portion (not shown) is carried by a door on the housing. The finder includes a mount 35 for the objective which, as described in the above-referred-to Specification, is simultaneously moved axially for focusing and transversely to its axis for parallax correction by means of cams 44, 45 and a worm 43 all carried by a shaft 41 mounted in, and travelling with, a slide or carriage 31 which carries the mount 35. Rotation of the shaft 41 to adjust the lens is effected by a control knob 124 carried by a shaft 122 in a control housing 120 secured to the wall of the camera housing 101. The shaft 122 is connected by tongue and slot elements 145, 123 formed of sound-deadening material such as fibre to a shaft 141 which is carried in ball-bearings in a bearing housing 135. The housing 135 is rotatably mounted in a further housing 134 which is secured in the control housing by a mounting ring 133, intervening rubber sleeves 131, 132 minimizing sound transmission. Motion is transmitted from the shaft 141 to the shaft 41 by means of an endless wire 171 passing around a pulley 146 on the shaft 141, over a double idler pulley 94, Fig. 6, round a pulley 85 on the shaft 41, Fig. 4, back to and around the pulley 94, and thence back to the pulley 146. The idler pulley 94 is mounted in ball bearings carried by a knuckle joint formed between U-shaped members 91, 111, the former of which is secured to links 88, 89 terminating in a forked eye-piece 87, Fig. 4, carrying ball bearings in which rotates the shaft of the pulley 85. The member 111 is carried from the rotatable housing 135 by a threaded turnbuckle rod 116 screwing into a sleeve 114 on the member 111 and an extension 161 of the housing, so that by rotation of the rod 116 the tension of the wire may be adjusted. The movement of the pulley 146 is limited by means of a pin 147 extending from it and engaging a pin 156 carried by a rotatable disc 151, this latter pin engaging in a slot 155 which limits the movement of the disc 151 to a degree which permits the pulley 146 to make one complete turn. The pivotal connection between the members 91, 111 allows the shaft 41 to move transversely to its length with the lens mount carriage 131, without affecting the drive of this shaft effected by the wire 171. When the camera is used without a housing the linkage may be removed from the shaft 41 by unscrewing the knob 81 and replaced by a knob for direct operation.