GB697197A - Improvements in or relating to the incorporation of exposure meters in photographic cameras for use with interchangeable lenses - Google Patents

Abstract

697,197. Photographic cameras combined with exposure meters. ZEISS IKON AKT.-GES. June 7, 1951 [June 7, 1950], No. 13550/51. Class 98 (i). [Also in Group XL (b)] A camera for use with two or more interchangeable lenses and incorporating an exposure meter includes means for taking into account the different speeds of said lenses in operation of the meter, said means comprising an adjustable member movable over a scale of lens speeds, movements of said member being transmitted independently of the lens diaphragm adjustment of the camera to the exposure meter through gearing adapted also to transmit to the meter setting movements for other exposure factors, e.g. exposure time or film sensitivity, so that the same sensitivity of the meter may be obtained whichever lens is in use since the light reaching the meter is the same for each lens. As shown, an aperture selecting wheel 3 is geared to the toothed rings 1, 6 of diaphragms for the camera objective and a photo-cell 7 which operates an electrical meter 8. A mark 10 carried by a disc 9 is brought into register with the meter pointer by adjustment of a shutter speed setting disc 14 which through a differential gear 13 rotates a worm 12 engaging the toothed edge of the disc 9. Allowance for film speed is made by adjustment of a disc 15 connected to the gear 13. To make allowance for different interchangeable lenses, a further differential gear 16 is provided between the worm 12 and the gear 13 and is adjustable by a lever 17 against a scale of f-numbers.