Patent GB-816480-A (GB)
Title: Improvements relating to photographic cameras
IPC: G02B7/12
Filed: 1956-04-23
Abstract: 816,480. Photographic cameras. DECKEL, H., and DECKEL, F. W. April 23, 1956 [April 29, 1955], No. 12357/56. Class 98(1) A photographic camerica with shutter speed and diaphragm aperture setting members, is provided with an exposure value control member which is coupled to one or both of them, and which is linked with a device for detecting the position of the pointer of a built in exposure meter, the device being initially held in an extreme-value position, and on release, urged by a spring into contact with exposure meter pointer. As shown in Fig. 1, the camera housing 1 mounts a shutter 2 and objective 3, and a meter 4 actuated by a photoelectric cell 5. A resistance 6 in the meter circuit takes account of film sensitivity and any filter which may be used. These factors may also be allowed for by rotating the meter body. The shutter speed is set by means of a knurled ring 10 with an index mark 12 moving with respect to a stationary scale 13. The diaphragm is adjustable by means of two independent setting members, one of which is connected to a manipulating ring 11 bearing an aperture scale 14 confronting the index 12, while the other member is coupled to the shutter speed setting ring 10 by means of an arm 28. Thus, when the ring 10 is rotated to adjust the shutter speed( the diaghragm is adjusted in the compensating direction whereas when the ring 11 is rotated, the total exposure value is varied as indicated by a scale 16 moving with respect to a fixed mark 15. To control the exposure value automatically, the manipulating ring 11 is coupled to a cam disc 31, which is of stepped form, and is rotated from an initial position until one of its steps encounters the pointer 32 of the meter, the pointer being held between clamping jaws 33, 34 (see Fig. 2) for the purpose. The cam is brought to its original position by the film winding operation, which is effected by a lever 7, which is rocked against a return spring 50. The lever is coupled to a toothed gear 51 which meshes with a gear wheel 52 freely mounted on the shaft 53 of the film sprocket roller 54. Gear 52 meshes with a wheel 55 which carries an upwardly and downwardly projecting catch pin 56, which, during the winding movement, engages a pin fixed to the toothed gear 57 which meshes with a tooth gear 58 pinned to the spindle 53. A disc connected to the spindle 53 has a one-way connection with the film sprocket roller 54. A spring-loaded pawl prevents return movement of the film spool sprocket 54. At the same time, the toothed gear 57 rotates a shaft 59, which through bevel gears 60 and gear wheel 61, rotates a shaft 9 to set the shutter, which is held in the set position by a detent 62. Also, during the film winding movement, the lower part of the pin 56 engages a pin 70 on a toothed gear 38 which moves the cam disc 31 to its starting position by means of a gear wheel 37, and at the same time moves the ring 11 to its extreme position through gear wheels 40, 39, 42. In this position the shutter is set to its highest speed and the diaphragm to minimum aperture. The sequence of the events prior to making an exposure are initiated by depression of a release button 90. First, an inclined surface 91 on the button 90 moves a clamping jaw 33, which grips the turned-over end of the meter pointer 32 between it and a fixed jaw 34. On further depression of the release button, a shoulder 92 thereon engages a detent 75. The dis-engagement of this detent allows the cam 31 to turn under the influence of a spring 74 until one of its steps engages the pointer 32. The ring 11 turns with the cam 31, so that the shutter is set to an exposure value which corresponds with the meter indication. On further movement of the release member, its end 93 engages the detent 62 and frees the shutter so that an exposure takes place. The successive impact at different stages of the movement of the release member 90 can be distinctly felt. After the second movement, the release button movement can be discontinued and any combination of shutter speed and diaphragm aperture consistent with the set exposure value may be chosen by rotating the shutter speed setting ring 10. Further depression of the release button causes an exposure to be made. Further, if the release knob 90 is not moved to its final position, it is possible by repeated actuation of the winding lever 7 to set a new exposure value. If the shutter has not been released, a new film-winding movement will not take place. In a modification, the film wind is separated from the cam re-setting means. A switching slide is provided which has three positions; in the first, the exposure value is determined for each exposure, and the film is rewound by a separate operation; in the second, a number of successive exposures are made without altering the exposure value set and in the third position the exposure value may be set by hand independently of the meter setting.