Electric shutter exposure time control circuit having counter light compensation

Claim 1

A photographic exposure control circuit for use in a camera having an electrically controlled shutter comprising, a switching circuit having a trigger level and triggered by trigger input exceeding said trigger level for controlling in use an electrically controlled shutter, an exposure control delay circuit connected to said switching circuit and having a lightresponsive element having an electrical parameter which varies in use in accordance with the quantity of light incident thereon from a respective portion of a field of exposure being photographed and including capacitoR means for developing a trigger signal applied as said input for triggering said switching circuit when said capacitor is charged to said trigger level, and a second light-responsive element connected in said switching circuit varying the trigger level thereof and having an electrical parameter which varies in use in accordance with the quantity of light incident thereon from a respective portion of said field of exposure and different from the first-mentioned respective portion of said field of exposure thereby to vary said trigger level as a function of the quantity of light received from said other portion, whereby the delay time of said exposure control delay circuit is in part a function of the brightness of said other portion of said field of exposure.