| 摘要 |
PURPOSE:To obtain a variable power finder which is small in size and has good appearance by consisting objective lens groups respectively of a piece of negative lens and eyepiece lens group of a piece of positive lens and constituting these lens groups so as to satisfy specific conditions. CONSTITUTION:The objective lens group having a negative refracting power and the eyepiece lens group which has a translucent face installed diagonally to the optical axis in order to guide the luminous flux from a light image frame to the pupil side and has a positive refracting power are provided, successively from an object side, to this finder. The magnification of the finder can be changed by attaching and detaching the other objective lens group having a different focal length and this objective lens exchangeably to and from the optical axis. The objective lens group as a piece of the negative lens and the eyepiece lens group as a piece of the positive lens are constituted to satisfy the equation I - the equation III. In the equations I-III, rOT is the radius of curvature of the object side face of the objective lens for high magnifications; r'OT is the radius of curvature of the observation side face of the objective lens for high magnifications; rE is the radius of curvature of the object side face of the eyepiece lens, rE' is the radius of curvature of the observation side face of the eyepiece lens. The finder which is small in size and has the good appearance is thereby obtd.
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