Single lens reflex camera equipped with mirror elevation detector and sequence control

摘要

A single lens reflex camera is provided with a photocell so positioned in the camera as to receive thereon light incident through the lens and reflected onto the photocell by the mirror. During each photographing operation, the mirror is pivotally elevated so that the incident light is no longer received by the photocell. The camera electronics monitors the photocell output which is representative of the magnitude of light received by the photocell and, unless a relatively rapid change in photocell output is detected during a photographing operation, an alarm is actuated to indicate failure of the mirror to properly pivot.