Exposure time control circuitry for cameras

Abstract

In an exposure time control circuit for a camera adapted for manual and automatic exposure control, the resistance of a single variable resistance element is varied by a first movable member moved in accordance with at least the setting of the film sensitivity and by a second movable member moved in accordance with the manually set exposure time. Switching means connect either the first or the second independently movable member into the time control circuit. A manually operable second switching means set to a first position produces a first output signal between a photoelectric element and the variable resistance and in a second position produces a second output signal formed between a fixed resistor and the variable resistance element. The first independently movable member may also be moved in accordance with the diaphragm aperture setting. The means for switching the first and second independently movable members may be interlocked with the second switching means controlling the automatic or manual mode of exposure control. An indication of the optimum exposure control may be provided in either the automatic or manual exposure control mode in a further modification of the apparatus which includes an additional switch associated with the variable resistance element and which is independently operable from the second means for switching.