PURPOSE: To improve the flexibility of the system by dividing electronic circuits to 3 blocks; an amplifier circuit which logarithmically compresses the output of a photoelectric transducer, an arithmetic circuit and a control circuit, and forming these circuits with integrated circuits.

CONSTITUTION: The first integrated circuit is formed by forming a photo diode 1 and a logarithmic compression amplifier circuit 2 in a hybrid integrated circuit. The second integrated circuit is formed by forming an arithmetic circuit 4 which calculates optimum exposure based on the output thereof as well as shutter speed value, film sensitivity value, etc. in a monolithic integrated circuit. Further the third integrated circuit is formed by forming a control circuit 5 for camera mechanism to which the operated outputs, release switch, etc. are inputted in a monolithic integrated circuit. Hence, packaging and assmebling may be made easy and the flexibility of the system improved because the electronic circuits are divided with consideration being taken for the transmission of signals and the size of the package