| 摘要 |
<p>PURPOSE:To measure object light efficiently and to eliminate the difference of a light measurement area even when a lens is interchanged by dividing a submirror by a boundary line which runs on the intersection of the optical axis of a photographic lens and constituting >=2 areas which differ in reflection direction characteristics. CONSTITUTION:Rays of light 11 incident on a point P1 from a photodetecting element 6 are diffuse-reflected within a narrow range by the upper Fresnel mirror 41 of the submirror 4 to form an area 11b and rays of light 12 incident on a point P2 form an area 12b at a lower part 42 similarly. Then, rays of light guided from the photographic lens 1 to the photodetecting element 6 backward through the optical path are divided into four sections on the submirror 4 to become rays of light of the four uniform areas. Therefore, the object light is measured efficiently and even if there is a difference in F value of an interchangeable lens at open aperture or if the lens is stopped down, variation of the light measurement area in a picture plane is eliminated.</p> |
