Programmed exposure control apparatus

Abstract

Exposure control apparatus provides an exposure program in which an exposure aperture is related to shutter speed to produce an optimum compromise between both exposure parameters. The exposure control apparatus comprises a diaphragm defining an exposure aperture of variable size, and a shutter comprising first and second selectively movable shutter blades for sequentially uncovering and covering the exposure aperture, respectively, during an exposure interval. Shutter speed is varied automatically by moving the second blade a variable time before commencing movement of the first shutter blade. The second shutter blade and diaphragm are coupled together by a control member such that the aperture size as well as exposure interval are varied in proportion to each other prior to an exposure. A movable latch member operably associated with a level-sensing light-sensitive circuit latches the diaphragm in an aperture regulating position which is functionally related to scene light intensity. As the diaphragm is latched the first shutter blade is synchronously actuated to uncover the exposure aperture. The time difference between the initial movement of the second shutter blade and the first shutter blade not only determines the exposure interval but also determines exposure aperture size. With this arrangement an exposure program exists providing an optimum compromise between exposure interval and aperture size wherein (1) under bright light conditions the exposure aperture is small and the exposure interval short, and (2) under low light conditions the aperture is large and the exposure interval relatively long.

Dependencies are inferred from the claim text.