US Patent 7692708 Photometric apparatus

A photometric apparatus having at least two photo-receivers, includes a single incidence optical system, wherein a light bundle carrying an object image which is passed through a focusing screen and exits out of an image-erecting system is incident on the single incidence optical system; a beam splitting optical system which splits the incident light bundle, that is incident on the single incidence optical system, into at least two light bundles by making a part of the incident light bundle pass through the beam splitting optical system and making another part of the incident light reflect from the beam splitting optical system; and at least one photometering optical system which makes the two parts of the light incident on the two photo-receivers, respectively.