| 摘要 |
PROBLEM TO BE SOLVED: To obtain an eyepiece capable of securing eye relief to be long to such an extent that it is not hard-to-use in usage even when a focal distance is short, and mainly obtaining optical performance and shape suitable to an image intensifier. SOLUTION: In this eyepiece 10, a 1st lens group G1, a 2nd lens group G2 and a 3rd lens group G3 are disposed in order from an observer side. The 1st lens group G1 has positive power, and the 2nd lens group G2 has negative power. The 3rd lens group G3 includes a positive lens L4, a negative lens L5 and a positive lens 6. The negative lens L5 of the 3rd lens group G3 turns its surface having the small radius of curvature to the observer side. The 1st lens group G1 is constituted of a single lens L1 which is biconvex and positive, and the 2nd lens group G2 is constituted of a doublet obtained by bonding a negative meniscus lens L2 turning its concave surface to the observer side and a positive meniscus lens L3 turning a concave surface to the observer side.
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