GB1185051A - Photoelectric Exposure Measuring Devices - Google Patents

Abstract

1,185,051. Exposure meters and exposure control devices. PENTACON DRESDEN KAMERAUND KINOWERKE VEB. April 5, 1967, No.15552/67. Heading G2A. A photo-electric light measuring device has at least one resistance attenuation element including first and second terminals and a sliding contact connected to an exposure setting or selecting member of a camera or a meter, a light-sensitive element subject to prevailing light conditions in circuit with the first and second terminals, and indicating means influenced by the light-sensitive element and the position of the sliding contact, such that correct exposure is achieved by adjustment of the setting or selecting member until a required indication dials. A voltage source 1 supplies a bridge circuit the balance of which is indicated by a glavanometer 2. The bridge includes a photo-conductive cell 3, a resistance 4, and a resistance 5 equal in value to the internal resistance of an attenuation element 6 serving as a logarithmic voltage divider. The bridge is balanced by adjustment of the element 6. In another embodiment Fig.2 (not shown) attentuation elements (6, 7 and 8) are provided in respect of exposure time, film sensitivity and diaphragm aperture controls. A switch (9, Fig. 3, not shown), is automatically opened upon attachment of an objective (not shown) to a camera to render attentuation element (8) built into pre-selector diaphragm effective. A lamp (14, Fig. 5, not shown) may replace the galvanometer 2, Fig. 1 to indicate the correct or incorrect setting of the exposure factor combination. The lamp (14) is connected to the attenuation elements (6, 7 and 8) through a trigger circuit (13).