Patent ID: 8896927

Claim:
A real-image variable-magnification viewfinder substantially consisting of: an objective lens system; an erect optical system formed by a plurality of optical members; and an eyepiece lens system having a positive refractive power, wherein the objective lens system substantially consists of four lenses including, in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, the first lens and the third lens are fixed relative to an optical axis direction during magnification change, and the second lens and the fourth lens are moved in the optical axis direction during magnification change, all optical surfaces of all the optical members forming the erect optical system are planar surfaces, at least one of the optical members forming the erect optical system is made of a glass material, and conditional expressions (1) and (2A) below are satisfied: 1.60<Nd (1) and 0.23<|γ·tan ω|<0.35 (2A), where Nd is a refractive index with respect to the d-line of the glass material, γ is an angular magnification of the entire system in a lowest magnification state and ω is a maximum half angle of view in the lowest magnification state.