| 摘要 |
PURPOSE:To detect focusing with high accuracy by leading the incident light passing through the peripheral two regions of an objective lens to a pair of reflecting mirrors provided symmetrically to optical axis and placing a focusing detecting element on optical path. CONSTITUTION:Reflecting mirrors 10, 10 are formed to one end of a ring-form mirror frame 11 which is rotatable about the optical axis 2 of a lens and are provided symmetrically with respect to the optical axis 2. A focusing detecting element 16 is disposed on the reflecting optical path of the reflecting mirrors 10, by which the detection of focusing is accomplished. At the time other than the focusing detection, the mirror frame 11 is turned to put the reflecting mirrors 10, 10 to outside 15 the effective image plane region, then the incident light path to the finder optical system and film is not hampered at all. Hence, such an inconvenience as darkening of the finder does no longer occur and since the reflecting mirrors are held fixed to the mirror frame, the focusing detection may be accomplished with high accuracy. |
