| 摘要 |
A real-image finder optical system includes a positive objective optical system, an image-erecting optical system and an eyepiece optical system, in this order from the object. The image-erecting optical system includes a pattern display surface having a reflective pattern, and a half mirror surface, transmitting a portion of the light rays incident from the object, and again reflecting the light rays having been reflected from the pattern display surface. The real-image finder optical system forms a real image of the object formed through the objective optical system and a virtual image of a pattern on the pattern display surface formed by an optical system including the half mirror surface so that an operator can simultaneously view both the real image of the object and the virtual image of the pattern through the eyepiece optical system; and the real-image finder optical system satisfies the condition:0<d1/fe</=0.1(1)wherein d1 designates the equivalent air thickness along the optical axis from the pattern display surface to the surface of the eyepiece optical system closest to the object; and fe designates the focal length of the eyepiece optical lens system.
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