To provide an eyepiece whose visibility can be adjusted and in which various aberrations such as a spherical aberration and a coma aberration are satisfactorily corrected.
An eyepiece comprises, in the order from an observation object side: a first lens group G1 having negative refractive power; a second lens group G2 having positive refractive power: and a third lens group G3 having negative refractive power. The second lens group G2 includes at least one aspherical surface, and by moving the second lens group G2 along an optical axis, visibility can be adjusted. The eyepiece satisfies conditional expressions (1): 0.25<d2/TL<0.50 and (2): 0.3<f2/f<0.6, where d2 is a movement distance of the second lens group G2 on the optical axis during the visibility adjustment, TL is a total thickness of the eyepiece (a distance on the optical axis from an optical surface of the first lens group G1 nearest to the observation object side to an optical surface of the third lens group G3 nearest to an eye point side), f2 is a focal distance of the second lens group G2, and f is a focal distance of the eyepiece at -1 [m-1].
| JP2005055874A | 2005-03-03 | |||
| JP2004258234A | 2004-09-16 | |||
| JPS60191221A | 1985-09-28 | |||
| JPH11109259A | 1999-04-23 | |||
| JP2005055874A | 2005-03-03 |
| US4593984A | 1986-06-10 | |||
| US20050013011A1 | 2005-01-20 | |||
| US4593984A | 1986-06-10 | |||
| US20050013011A1 | 2005-01-20 |
Hiroshi Kawano
Namiki Toshiaki
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