Control circuit for electronic shutter for electronic shutter having battery-checking circuit

Claim 1

An electronic shutter control circuit for a camera shutter electronically controlled comprising, means comprising, a lightresponsive element sensing light received from a scene to be photographed for controlling exposure time as a function of the intensity of light received, a switching circuit connected to said means to control the closing of a shutter, a light-intensity indicating circuit having an ammeter for indicating visually the intensity of the light at said scene, a power source for selectively energizing the light-responsive element, a power source checking circuit for checking the current delivered from said power source to determine its adequacy, switch means to independently control exposure time when takinG an exposure, taking a light intensity reading on said ammeter and a reading on said ammeter of the current available from said power source, the first-mentioned means including a capacitor connected to said light responsive element defining an RC time constant circuit therewith, for controlling said exposure time, means connecting said ammeter and light-responsive element in series between a terminal of said power source and an input of said switching circuit, and said switch means including a change-over switch normally short-circuiting the capacitor.