| 摘要 |
PROBLEM TO BE SOLVED: To obtain a finder optical system having large observation magnification, while keeping high optical performance and attaining observation of a large finder image. SOLUTION: The finder optical system for observing an object image formed by a photographic lens from an observation side has a roof-type first reflection surface for reflecting luminous flux, based on the object image to the object image side; a second reflecting surface for reflecting the luminous flux reflected by the first reflecting surface to an observation side; an eyepiece part on which the luminous flux from the second reflecting surface is made incident. The second reflecting surface is a rotationally asymmetric surface, and the eyepiece part has at least one rotationally asymmetric surface. The rotationally asymmetric surface, constituting the second reflecting surface comprises a surface-symmetric shape having one surface as a symmetric surface; and when power in the one surface is defined asϕ<SB>02</SB>and power in a surface perpendicular to the one surface is defined asϕ<SB>20</SB>,ϕ<SB>20</SB><ϕ<SB>02</SB>is satisfied. COPYRIGHT: (C)2008,JPO&INPIT
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