Electric exposure meter

Claim 1

An exposure measuring system comprising a gang swich including first and second movable contacts mechanically and electrically connected with each other, and two groups of corresponding fixed contacts arranged so that when the first movable contact is engaged with any one of the first group of fixed conTacts the second movable contact is engaged with the corresponding fixed contact; a photoconductive element and a load resistance connected in series, said photoconductive element being connected to said first movable contact while said load resistance is connected to said second movable contact; two groups of resistances each comprised of a plurality of equal value resistors connected in series, another resistance connected between said two groups of resistances, one end of said series connected resistances being connected to a DC electric source, each of said fixed contacts being connected to one end of an associated resistor so that in any contact position of said gang switch the voltage across the opposite ends of said series connection of the photoconductive element and load resistance is the same; and measuring means connected between the photoconductive element and the load resistance for measuring the voltage across the load resistance; whereby the output voltage is in linear relation relative to the brightness value of the object as sensed by the photoconductive member.