Photographic cameras having built-in exposure meters

917,907. Photographic cameras with built-in exposure meters. KAMERAUND KINOWERKE DRESDEN VEB. Jan. 24, 1961, No. 2765/61. Class 98 (1). In a photographic camera with a detachable rear wall and a built-in exposure meter which is coupled with setting members for exposure factors including film sensitivity, on the setting member for the film sensitivity there are secured one end of a return spring and a catch disc held by a catch spring, and control means is provided operable by the detachable rear wall to maintain the catch spring in engagement with the catch disc when the rear wall is in position on the camera and for moving the catch spring out of engagement with the catch disc when the rear wall is removed to allow the return-spring to return the setting member for the film sensitivity to a predetermined position where the exposure meter is inoperable or indicates non-setting of the film sensitivity, the exposure meter being rendered operable or indicating setting of the film sensitivity on further setting of the film sensitivity setting member after the rear wall has been replaced. As shown, the position of a follow-up member 6 for a photoelectric exposure meter pointer 36 is controlled by a lever 5 pivoted on a T-shaped slide 7, the position of which is determined by a cam 8 fixed to the shaft which carries the film sensitivity setting member 33. In use the diaphragm is adjusted by means of an arm 35 and through a cam surface 27 on the diaphragm operating arm moves endwise a shaft 1 carrying a pinion 26 engaging a shutter speed setting member 3. The shaft 1 is threaded at 2 to engage a nut 4 constrained by a fixed pin 25 to move axially. Thus both diaphragm and shutter speed adjustments through the positioning of the nut 4 engaged by lever 5 alter the position of the followup pointer 6. On removing the camera back 13 a pivoted lever 14 is pressed outwardly by a spring 15 and frees a catch disc 9 on the film sensitivity setting shaft from a catch spring 10, and a return-spring 11 secured between the cam 8 and the camera housing 23 rotates the cam until the cam nose 8a is arrested by a fixed pin 12 and the tail of the T-shaped slide 7 rests in the cam recess 8b, so that the lever 5 allows the spring 31 to move the follow-up pointer out of the exposure meter window 34. On reclosing the camera, e.g. after changing the film, the cam 8 remains in the position to which it moved on removing the camera rear wall, and before the exposure meter can be used as a fo