Patent GB-968098-A (GB)
Title: Photographic camera with an automatic exposure value setting device
IPC: G03B7/12
Filed: 1961-03-01
Abstract: 968,098. Photographic cameras. AGFA A. G. March 1, 1961 [March 4, 1960], No. 7541/61. Heading G2A. A photographic camera of the type having an automatic exposure value setting device controlled by a photo-electric exposure meter and arranged for actuation by a manually operable release includes a shutter, a diaphragm the leaves of which are mounted between two diaphragm rings both of which are arranged for individual rotational movement to set the diaphragm, and a rotatable manual exposure value setting means, the arrangement being such that from an intermediate setting position allowing automatic exposure value setting, the said setting means is rotatable in both directions for manual setting of exposure values, in each of which directions it moves a different one of the diaphragm rings and in at least one of which directions it also moves a shutter control member. In a first embodiment (Fig. 1), the diaphragm blades 5 are mounted between two blade rings 3, 4, each of which possesses an abutment 25, 26 respectively which is spring-urged in the idle position shown into engagement with a fixed stop 24. The manual exposure value setting means comprises a ring 28 having gripping projections 29 and an index 30. With this index set against the mark A (as shown), automatic exposure value setting is obtained as follows. On depression of a pivoted body release key 61 against loading of a strong spring 62, an exploratory slide 54 having a pin 64 engaging said key is allowed to move downwards under loading of a spring-urged lever 40 having a pin 52 engaging a cam 53 of the slide 54 until a cam surface 56 of the slide 54 engages the pointer 58 of an exposure meter (not shown). Movement of members 54 and 40 is thereby halted in a position corresponding to the prevailing light conditions. By means of a cam surface 46 formed on an extension 45 of the member 40, the toothed segment 12 of a conventional gear retard mechanism is set to give a suitable exposure time having regard to these conditions. At the same time, by means of a lever 38 pivoted about the same pivot 39 as the lever 40 and spring urged into abutment with a stop 48 thereon and further by means of a link 36, the diaphragm ring 3 is rotated to provide a suitable diaphragm aperture, again having regard to said conditions. Further movement of the key 61 releases the shutter. If the ring 28 is rotated so that index 30 registers with range 31a of the setting scale 31, then recess 50 in ring 28 is moved out of the move - ment path of a pin 49 on the member 40 thereby rendering the automatic setting mechanism inoperative, a pin 34 on ring 28 engages with key 25 on the spring urged diaphragm ring 3 and adjusts the diaphragm to the desired aperture value and the wide portion of a cam opening 32 in ring 28 moves into registry with a pin 33 on a lever 20 to render a "B" exposure device operative. Conversely, if the ring 28 is rotated so that index 30 registers with range 31c of the scale 31 then again the automatic setting mechanism is rendered inoperative by movement of the recess 50, the diaphragm aperture is set as a result of the engagement between the pin 34 and lug 26 of the diaphragm ring 4 (urged by spring 42 through coupling members 38 and 36) and the shutter is left unadjusted at its slowest speed suitable for flash exposures. In a modification (Fig. 2 - not shown), instead of the exposure-time setting cam surface 46 being carride by the member 40, it is formed in the ring 4. Operation of the embodiment is similar to that described above. In a third embodiment (Fig. 3), provision is made in the manual setting ranges for taking photographs with either maximum possible depth of field (range 79c) or maximum possible shutter speed (range 79a) having regard to the light value set. For this purpose, ring 28 has an opening 78 formed therein with cam surfaces 78a-78d which are engaged in the different setting positions of the ring 28 by a rearward extension 76 of the pin 47 of the shutter retard mechanism. Openings 73, 77 and 75 are cut in various members to allow passage of this pin 76. The ring 28 may be coupled to the follow-up pointer of an exposure meter. The automatic setting mechanism in this embodiment functions in the same way as in the first embodiment.