Patent ID: 7630627

Claim:
A viewfinder optical system comprising: a first mirror having a roof shape configured to reflect light from an object image formed by a photographic lens towards the object image; a second mirror configured to reflect light reflected from the first mirror towards an observation side; and an eyepiece lens configured to receive light reflected from the second mirror, wherein the second mirror has a focal power and includes a rotationally asymmetrical surface, wherein the eyepiece lens includes at least one rotationally asymmetrical surface, wherein the eyepiece lens includes a plurality of lenses, among which a lens closest to the second mirror includes a rotationally asymmetrical surface, wherein the eyepiece lens includes at least one positive lens positioned at the observation side relative to the lens closest to the second mirror, and wherein the at least one positive lens is movable along an optical axis of the eyepiece lens to perform diopter movement.