Real-image finder optical system

A real-image finder optical system comprising:

• a positive objective optical system in which an image of an object, being upside down and reversed from left to right, is formed;
• an erecting optical system, having a plurality of reflection surfaces, in which said image formed by said objective optical system is erected to the same orientation as said object;
• and
• an eyepiece optical system through which said image erected by said erecting optical system is viewed;
• wherein a shape of a finder field of view is a rectangle having major sides along the transverse direction in said finder field of view;
• wherein along the optical path on the side of said object with respect to said image formed by said objective optical system, at least three reflection surfaces of said erecting optical system are provided, and
• wherein the most object-side reflection surface among said three reflection surfaces is positioned so that the optical axis is deflected in a direction along said major side of said rectangular finder field of view.