| 摘要 |
PROBLEM TO BE SOLVED: To provide an eyepiece optical system that has a simple lens configuration, has a high observation magnification while retaining high optical performance, ensures the observation of a large finder image and, moreover, obtains sufficient long eye relief, and to provide a finder optical system having the eyepiece optical system. SOLUTION: The eyepiece optical system includes: an image inverting means by which an image formed by an objective lens is inverted into an erect image; and an eyepiece lens section which magnifies and displays the erect image formed by the image inverting means. The eyepiece lens section includes, in order from the image inverting means side: a first lens with negative refractive power; a second lens with positive refractive power; and a third lens with positive or negative refractive power, which has a concave face and a meniscus shape on the observation side of it. The second lens has a visibility adjustment function that moves along the optical axis of the eyepiece lens section and adjusts visibility. If the focal distance of the first lens is f1 and the air conversion optical path length of the image inverting means is dp, a condition expressed by 1.33<¾f1/dp¾<2.10 is satisfied. COPYRIGHT: (C)2008,JPO&INPIT
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