Exposure control system for lens interchangeable cameras

摘要

In an exposure control system for a camera having an interchangeable objective lens, a diaphragm mechanism defining the diaphragm aperture, a preset means for presetting the f-number of the diaphragm aperture and a shutter mechanism for effecting an exposure, a light measuring circuit generates an output signal having a level representative of the light from an object to be photographed and a reference signal circuit generates a reference signal having a predetermined level. A programmed signal circuit generates a programmed signal in accordance with the output signal and the reference signal, and an exposure control circuit controls both the diaphragm and the shutter mechanisms such that the diaphragm aperture and the shutter speed have a combination of values commensurate with the programmed signal. The programmed signal circuit includes a variable member having an electric parameter variable in accordance with the number of steps of the diaphragm aperture from the minimum f-number to a preset f-number.