| 摘要 |
PROBLEM TO BE SOLVED: To change the diopter of a finder optical system without the complication of the constitution and to correct the diopter in a wide range by constituting a diopter correcting lens so that it can be attached/detached to/from the eye point side of an eyepiece and it may be provided with 1st and 2nd lens groups having respectively a negative refractive power and a positive refractive power from the eyepiece side, moving the 2nd lens group in the optical axis direction and changing the diopter of the finder optical system. SOLUTION: The diopter correcting lenses 4 and 5 are freely detachably attached behind the eyepiece 3 of the finder optical system. The diopter correcting lens is constituted of the 1st lens group 4 whose refractive power is negative and the 2nd lens group 5 whose refractive power is positive arranged in order from the eyepiece side. And by moving the 2nd lens group 5 in the optical axis direction, the diopter of the finder optical system is changed. An optional diopter is obtained in a wide diopter correction range by the works of two lens groups 4 and 5. Besides, it is preferable that 0. 7<|f1|/f2<1.0 is satisfied. Provided that f1 and f2 separately denote each focal distance of the 1st and 2nd lens groups.
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