GB1321492A - Photographic camera - Google Patents

Abstract

1321492 Controlling exposure PENTACON DRESDEN KAMERA-UND KINOWERKE VEB 30 June 1971 30680/71 Heading G2A In a camera, photo-electric exposure measurement through the picture taking lens may be achieved either using "open" or "working aperture", there being a separate actuating key 1, 6 for each position and a change-over switch 5 whereby either a resistor 24 variable with a diaphragm setting member 17 for open aperture measurement or a parallel substitute 27 for working aperture measurement is connected into a bridge measuring circuit. The latter consists of a battery 10, resistors 21, 22 in adjacent branches, a resistor 23 variable with exposure time in another branch, a galvanometer 11 connected across a diagonal and a further operating switch 4, 7. In a rest position Fig. 2 resistor 24 is connected into the bridge and after depression of Key 6 for open aperture measurement, resistors 23 and 24 are varied to achieve a zero galvanometer reading. For working aperture measurement Fig. 3 (not shown) Key 1 actuates switch 5 to bring resistor 27 into the circuit and to switch out resistor 24 and movement of Key 1 also moves diaphragm setting member 17 to close diaphragm blades 16 partially according to the setting of member 17, by abutment of a stop 14 on nose 18. A galvanometer balance is then achieved by adjustment of resistor 23. In an alternative embodiment Fig. 4 (not shown) in a rest position, resistor 27 is in the bridge circuit and switch 5 is actuable by a Key (36) for open aperture measurement. A return spring (38) urges switch 5 to the rest position.