| 摘要 |
PURPOSE:To simplify structure and to increase the degree of freedom of design, by attaching a small mirror to the back of a single-lens reflex mirror. CONSTITUTION:A photographic lens 1, single-lens reflex mirror 2, film surface 3, and the pentagonal prism 11 of a viewfinder optical system are provided. Further, a light transmission part is provided at the center part of the single-lens reflex mirror 2, and a flat prismatic mirror 12 with convex section is provided to its back at right angles to the single-lens reflex mirror 2 in an observation state (as shown in a figure); and this mirror splits the optical-axis light of the photographic lens 1 into two containing an angle 2DELTA as shown in the figure, and elements 5 and 6 for detecting the amount regarding a focusing state are arranged on the split optical paths respectively. |
