Exposure indicating devices for single reflex cameras

Abstract

An exposure indicating device for single lens reflex cameras which are selectively settable to automatic aperture control or automatic shutter speed control modes includes an exchangeable lens which has first and second information transmitting members, and a diaphragm setting member settable to one of a number of manually set aperture positions and to an automatic aperture control position. The first transmitting member transmits to a first information receiving member, first information of the step-difference from a minimum to a preset f-number of the lens independently of the set position of the diaphragm setting member. The second transmitting member transmits to a second information receiving member, second information of a maximum f-number only when the diaphragm setting member is set to the automatic aperture control position. The second transmitting member also serves as a mode selection and scale selection member which switches the camera into the automatic aperture control mode and enables observation of an aperture scale within a finder view field when the diaphragm setting member is set to the automatic aperture control position. The second transmitting member also switches the camera into the automatic shutter speed control mode and enables observation of a shutter speed scale within the finder view field when the diaphragm setting member is set to any one of the manually set aperture positions. The first information thus received enables automatic shutter speed control, and indication of an automatically controlled shutter speed prior to a stopping-down operation. The first and second information thus received are composed with each other, only in the automatic aperture control mode, to generate information of the minimum f-number of the lens, which enables indication of an f-number corresponding to an automatically controlled aperture prior to the stopping-down operation.