| 摘要 |
A real image mode variable magnification finder optical system comprises a variable magnification objective optical system having a positive optical power, an ocular optical system having a positive optical power, and a plurality of reflecting surfaces for erecting an image. The objective optical system comprises a plurality of movable lens units and at least one rotationally asymmetric reflecting surface having an optical power, and the reflecting surface participating in the function of the objective optical system and in the function of erecting an image. Each of the lens unit included in the objective optical system has at least one aspherical surface. The finder optical system satisfies the following condition: <paragraph lvl="0"><in-line-formula>0.02<d.(fw/ft2)<0.4. </in-line-formula>where d is a distance from a first surface of the objective optical system to one of the reflecting surfaces positioned nearest to an object measured along an axial chief ray at a wide angle end, fw is a focal length of the objective optical system at a wide angle end, and ft is a focal length of the objective optical system at a telephoto end.
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