| 摘要 |
PURPOSE:To obtain an optical system of irreducible necessary consitution, by performing focusing detection by extending as a focusing detecting block a part, which should be at a focus position, to a position optically equivalent to a film surface at the lower part or side part behind a moving mirror. CONSTITUTION:The optical system, reflecting a luminous flux from an object passed through photographic lens 2 to a finder system by moving mirror 6, enables the focusing state to be observed facing to the object via focusing plate 10 and also displays the exposure by the output of the photometric element 14. In this state, part of the luminous flux of the object from photographic lens 2 passes through light transmission part 6a of moving mirror 6 and is led to focusing detecting block 15, extending to a position optically equivalent to the film 5 surface under mirror 6, by auxiliary mirror 8 provided behind the part 6a. Consequently, the optical system has irreducible necessary constitution and its light loss can be minimized. |
