| 摘要 |
PURPOSE: To provide a small eyepiece capable of forming a long optical path from an image forming surface to the eyepiece lens and having a large diameter of a pupil and a short focal length by composing the eyepiece of a positive meniscus lens, whose convex surface confronts the object side and both surfaces are aspherical, satisfying a specified condition. CONSTITUTION: An eyepiece system is composed of an image forming surface S of an image by an objective lens, a prism P having image inverting action, an eyepiece lens L and an optical axis Lc. The eyepiece lens L has a convex surface on the object side and both surfaces are aspherical. It is composed of a positive meniscus lens whose both surfaces have aspherical shapes and the convex surface confronts the object side and the conditional relation: -1×10<-3> <X1 /f<0 is satisfied. In the relation, f: the focal distance of the eyepiece system and X1 : the deviated amount of a surface on the object side from a reference spherical surface on the position of height 0.12f from the optical axis. Consequently, spherical aberration and coma aberration are compensated in a well-balanced manner.
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