Dedicated photographic flash system for varying flash spread based upon

Abstract

A dedicated electronic flash unit for automatically varying flash spread based on camera-to-subject distance. Specifically, in one embodiment, a light source includes a flash tube mounted adjacent a reflector. An actuator comprises an electric stepper motor for controlling the movement of a pair of opposed diffusion plates. The actuator includes a pair of armatures that are energized, in response, to the output of the camera's rangefinding system. When a photograph is to be taken, the diffusion plates are pivoted by the actuator to one of three different positions. In one position, the neutral position, the diffusion plates are positioned on opposite sides of the reflector. In a second position, the actuator pivots the diffusion plates such that one of the plates covers the light output of the reflector to create wide-angle illumination of the subject. In a third position, the actuator pivots the other diffusion plate into position to cover the reflector output in order to further increase the angle-of-illumination. Other embodiments utilize a sectioned cylindrical lens-diffuser which is rotated into a proper position or a single diffuser that is moved towards or away from the flash tube to vary the flash angle-of-illumination with changes in camera-to-subject distance.