| 摘要 |
A high-performance real-image finder optical system reduced in size, particularly in thickness, includes a positive objective optical system, an image-inverting optical system for erecting an intermediate image formed by the objective optical system, and a positive ocular optical system. The objective optical system has at least two movable units moving when zooming is performed. A prism is placed on the object side of the intermediate image. At least one reflecting surface of the prism has a rotationally asymmetric surface configuration. At least one reflecting surface of the image-inverting optical system is formed from a roof surface. The finder optical system satisfies the following condition:where d is the distance from the entrance surface of the objective optical system to the first reflecting surface of the image-inverting optical system; fW is the focal length of the objective optical system at the wide-angle end; thetaW is the maximum field angle of the objective optical system at the wide-angle end; and Z is a zoom ratio.
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