Abstract: An exposure control system for photographic apparatus utilizing electrically controlled shutter-diaphragm blades mechanically latched in a light-blocking condition in conjunction with a latch actuator which delays return of the released latch to the blade path prior to commencement of the exposure interval during which scene light is passed to the film. In the illustrated embodiment, the actuator enables a latch element for release and energizes the blades to draw them slightly further in a light-blocking direction from the latched position so as to release the latch just prior to initiation of the exposure interval, and the actuator includes an over center spring arrangement which provides a decrease in the required force of actuation as the system is electrically energized so that the operator inherently holds the actuator in an operating position with the latch element held out of blade engagement for a time sufficient to allow escape of the blades from the latch position.