Photometric circuit of photographing apparatus

Abstract

Abstract PURPOSE: To achieve the improvement in the accuracy of photometric outputs with a simple constitution by dividing the illuminamce range of incident light and operating corresponding amplifier circuits. CONSTITUTION: Detection signal of incident light by a photoelectric transducer 21 is applied to a comparator 29 formed of an operational amplifier to which a reference voltage is applied, by way of operational amplifiers 22, 26. When the illuminance is large, the amplifier 26 saturates and the output of the comparator 29 which is set with the reference voltage slightly lower than the saturation voltage thereof inverts to become low level. this causes a transistor 36 to conduct and a relay 38 to be energized, by which the connection of a switch 24 is changed over. Hence, at the time of low illuminance, the photometric output of the amplifier 28 is applied to an integration circuit and at the time of high illuminance, the photometric output of the amplifier 22 is applied thereto, thus the photometry is accomplished through the amplifier which is not saturated COPYRIGHT: (C)1979,JPO&Japio

Inventors

• 👤 Tsuyoshi Matsuura

Bibliographic Details