Patent GB-368260-A (GB)
Title: Improvements in or relating to colour photography
IPC: G03B33/00
Filed: 1930-11-24
Abstract: 368,260. Colour photography. COLOUR PHOTOGRAPHS (BRITISH & FOREIGN), Ltd. and OLIVER, L. W., Victoria Road, Willesden, London. Nov. 24, 1930, No. 35277. [Class 98 (ii).] A movable back, for use on a camera, of the type comprising a carrier for two or more films side by side, means to effect stepwise movement of the carrier to present the films in succession opposite the lens, a shutter-operating member co-ordinated with the carrier movement to operate the shutter for a predetermined time between successive steps, and dashpot control means for the shutter-operating member, is characterized by the provision of independent regulating means for setting the speed of the dashpot, in each shutter-operating position of the parts, separately for each exposure. As shown in Figs. 1, 2, and 6, the carrier 14 has a ground glass screen 35 and a dark slide containing three films 36, 37, 38 and their respective colour filters. When the screen 35 is opposite the lens, the shutter is held open by the stop 39 on the slide 14 depressing the lever 40 to cause the pin 42 to engage the release 31. The handle 49 geared to the spindle 46 winds a spring 48 attached to a drum 47 prevented from rotating by a stop engaging a recess and releasable by a thumb-piece or the antinous release. Around the drum 58 on the spindle 46 is wound an endless wire 59 attached to a plunger 61 moving in the dashpot 62 containing a non-compressible liquid. The front face of the disc 63, having on the other side two pins 65 and 68, has a face cam 64 and a spiral groove 69 co-operating with the pin 70 of the lever 71. When the spring is wound the cam 64 engages the lever 73 and moves the shutter release 31 against the spring 45 until it is locked by the pin 42. The slide 14 is moved manually until the stop 76 encounters the pin 68, when the first film is in position. The catch 39 releases the lever 40 which frees the pin 42 and permits the shutter to close. To effect exposure, the release is maintained depressed until all the films have been exposed. During the first half revolution of the spindle 46 the shutter is released by the cam 64. The time of exposure is controlled by the valve 81 in the byepass pipe 180 of the dashpot 62. The pin 65 engages the slot 66 and brings the second film opposite the lens. During this operation the shutter remains closed, and the plunger moves along the dashpot between the parts 80, 84, the displaced liquid flowing freely through the byepass 181. The third and fifth half-revolutions correspond to the first, the second and third films 37, 38 being respectively exposed. The fourth half-revolution corresponds to the second, the pin 65 engaging the crosshead slot 67 and moving the third film 38 up to the exposure station. At the end of the fifth half revolution the mechanism is stopped by the pin 70 reaching the end of the slot 69. The framework carrying the slide 14 has a catch 91 adapted to engage the notches 90 to prevent slipping when arranged vertically. In a modification the films and the colour filters are mounted on opposite sides of the ground glass screen 35, and when the films are moved up to the exposure position by the pin 65 engaging the slots 66, 67, the filters, by means of a pinion and two racks attached to the films and filters respectively, are caused to move up in the opposite direction. A modified dashpot is circular and provided with a fixed vane, and a removable vane coupled to the spindle by gearing, and has byepass mechanism similar to that described.