Metering system using a focus detecting optical system

Claim 1

In a device having a focus detecting system and an exposure measuring system, said focus detecting system comprising: (a) an optical system for focus detection; (b) first photoelectric means for the focus detection, said first photoelectric means being arranged to receive light from an object through said optical system and to produce an output signal in response to the received light; and (c) first circuit means for the focus detection, said first circuit means being arranged to receive the output signal of said first photoelectric means and to provide a focus related output signal on the basis of the received signal; an exposure measuring system including (A) second photoelectric means for exposure measurement, said second photoelectric means being arranged to receive the light from the object through said optical system for the focus detection and to produce an output signal in response to the received light; and (B) second circuit means for exposure measurement, said second circuit means being arranged to receive the output signal of said second photoelectric means and to provide an exposure related output signal on the basis of the received signal, wherein said optical system includes light dividing optical means for distributing the light to said first and second photoelectric means and having two different types of area type beam splitting surfaces each area type beam splitting surface having a pattern with a plurality of light transmitting parts and a plurality of light reflecting parts, said second photoelectric means being arranged together with said first photoelectric means to receive the light divided by said optical means, said first photoelectric means having a plurality of photoelectric elements arranged to receive the light divided by respective area type beam splitting surfaces.