| 摘要 |
PROBLEM TO BE SOLVED: To make finder magnification exceed unmagnification in an Albada type finder. SOLUTION: This finder is constituted of a positive first lens L1, a negative second lens L2, a positive third lens L3, and a negative fourth lens L4 in order from an object side, an objective lens system LA is constituted of the lenses L1, L2, and L3, an eyepiece lens system LB is constituted of the lens L4, a surface on the side of the exit pupils E and P of the lens L2 is defined as an Albada reflection surface AR, a parallel plate PG having a field frame FF is inserted between the lenses L2 and L3, this frame FF is reflected by the reflecting surface AR, and observation is performed from the side of exit pupils E and P. In this case, the conditional expression of 0.75<Ra/Fo<1 is satisfied, provided that Ra is defined as the radius of curvature of the Albada reflecting surface, and Fo is defined as the focal distance of the objective lens.
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