| 摘要 |
A compact, real-image-type zoom finder having a high zoom ratio and high optical performance is provided. The finder is formed of an objective optical system and an erecting eyepiece. The objective optical system is formed of, in order from the object side, a first lens element having negative refractive power with a concave surface on the object side, a second lens element having positive refractive power, and a third lens element that is a positive meniscus lens with its convex surface on the object side. The erecting eyepiece is formed of an erecting prism having refractive surfaces integrally formed on the input end and output end of the erecting prism. The magnification of the finder is changed by moving the second lens element along the optical axis, and the third lens element is moved along the optical axis in order to adjust for what would otherwise be a shifting in image surface position with the change in magnification. Specified conditions are satisfied in order to provide a compact structure and high image quality.
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