PURPOSE: To make the exposure at the strobe photographing correct with simple constitution by so constituting the camera that the diaphragm aperture information of the photographic lens is transmitted to the camera side with sptical method and the diaphragm is automatically set to a desired aperture value at the strobe photographing.

CONSTITUTION: The photodetecting part 22 of a control signal output device 21 is constituted by a plurality of photodetectors assuming the shape corresponding to the change in the image of the exit pupil of the diaphragm 33 imaged by a lens part 35a for imaging. The respective photodetectors CdS1WCdS5 are respectively connected to a diaphragm aperture and subject luminance ditecting circuit IC1. From the circuit IC1, diaphragm aperture information AWD and subject luminance information E are outputted respectively. An aperture value operating circuit IC2 calculates the correct aperture value from the input information AWE, film sensitivity information G and shutter second time information H and outputs the aperture control signal I to an exposure meter. In this way, the exposure at the strobe photographing may be made correct with simple constitution.