Abstract: An electrical shutter circuit for a camera includes a photoelectric transducer element which is responsive to light from an object being photographed to determine a proper exposure period in accordance with the brightness thereof, thus automatically controlling the operation of a shutter assembly which opens or closes an exposure light path. In the open position of the shutter assembly, the photoelectric transducer element is irradiated with light of a fixed, relatively low intensity emitted by a luminescent element so that the electrical shutter circuit is automatically operated for the closing operation after a period of time determined by the light from the luminescent element even if the incident light from the object being photographed is extremely weak or completely absent.

Abstract: A photometric apparatus for single lens reflex camera and of the type in which an exposure value is determined by photometry of light which is transmitted through a photographic optical system and is reflected by at least one of the surfaces of a shutter blind and a film, said apparatus comprising a photoelectric transducer element for receiving light reflected by at least one of the surfaces of a shutter blind and a film, and an operational amplifier for biasing the photoelectric transducer element to maintain the voltage applied thereacross substantially null, thereby enabling a photometric output of the photoelectric transducer element to be effectively derived even when the amount of light received is minimal.