Patent ID: 7050239
Filing Date: 2006-05-23
Classification: G02B

Abstract:
1. A real image mode variable magnification finder optical system comprising: 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 of an object to be observed; said objective optical system including a plurality of movable lens units each of which has an aspherical surface, and at least one reflecting surface which is a rotationally asymmetric surface and has an optical power; said finder optical system satisfying the following condition: where d is a distance from a first surface of said objective optical system to one of said reflecting surfaces positioned nearest to an object measured along an axial chief ray at a wide angle end, fw is a focal length of said objective optical system at a wide angle end, and ft is a focal length of said objective optical system at a telephoto end.