Patent GB-849944-A (GB)
Title: Improvements in or relating to two-film photographic cameras
IPC: G03B19/06
Filed: 1958-01-28
Abstract: 849,944. Photographic cameras. KAMERAWERKE NIEDERSEDLITZ VEB. Jan. 28, 1953 [Oct. 22, 1957], No. 2768/58. Class 98(1) A two film reflex camera has a single shutter which exposes either film and two reflex mirrors to select the film to be exposed. As shown, two mirrors 72, 721 (Fig. 4) lie between two films 2, 2<1> and are surrounded on three sides by a roller blind shutter having blinds 10 and 11 (Figs 1 and 4). The finder image is formed on the plane ground side of a plano-convex field lens which is arranged adjacent aperture 47. The image is viewed erect and unreversed by either of two erecting systems (Figs 18 and 19, not shown). Since the shutter uncovers both films each time it is operated, which film is exposed is determined by which mirror 72 or 721 is released to assume an inclined position under the action of a spring (not shown). The appropriate mirror is selected by moving shaft 67 axially so that one cam 80 or 801 is opposite a mirror releasing slide rod 78 or 78<1> (Fig. 4). Shaft 67 is moved axially by cam 63 or spring 64 turning lever 65 about pivot 66 (Fig. 2). Simultaneously the drive to one film 2 or 2<1> is connected and the drive to the other 21 or 2 is disconnected. Thus shaft 67 turns plate 35 about pivot 43 to mesh or unmesh wheels 36 and 37 of the drive to film 2 and arm 50 is turned by cam 55 on spring 56 about pivot 49 to unmesh or mesh wheels 52 and 59 of the drive to film 21. The mirrors 72 and 721 are retained in the horizontal position against resilient light seals 75 and 751 by leaf-spring 76 and on depressing release button 103 lever 109 (Fig. 11) turns about pivot 111 under spring 112 and turns lever 114 about pivot 115 so that shaft 67 is rotated by the co-action of members 116 and 117. The operative cam 80 or 801 thus slides rod 78 or 781 axially to disengage one end of spring 76 from mirror 72 or 721. Member 116 also releases rail 167 so that it can move towards the objective (at the right of Fig. 4) and set the diaphragm to the pre-selected aperture. Each mirror 72 and 721 carries a shutter releasing pin (Figs. 6-9, not shown) and the shutter is released as the mirror reaches its inclined position. The shutter is re-wound and the exposed film changed by rotating a knob on shaft 30 (Fig. 2). Wheel 46 is rotated by the terminal shutter setting wheel 23 and brings the drive to wheels 48, 52, 53 and optionally to 59 and the sprocket 401 of film 21. Cam 81 (Fig. 4) is rotated by wheel 46 to return the inclined mirror to the horizontal position and rail 167 to its locked position. Cam 163 (Fig. 11) is carried by wheel 48 and engages pin 164 to return levers 114 and 109 to their pre-release positions. A member on lever 109 is simultaneously removed from a notch 174 in disc 173 on shaft 58 so as to allow a change to be made in the film to be exposed. A delayed action self-timer having anchor 152 (Fig. 11) and escape wheel 151 is wound by wheel 144 co-axial with shaft 58 and held, before release, by the engagement of arm 153 on lever 109 with anchor 152. On release, lever 109 moves to free the anchor but cannot turn lever 114 until the timer has run out sufficiently for pin 154 to allow lever 155 to be rotated about pivot 156 by spring 160 so as to withdraw pawl 157 from member 113 of lever 114.