| 摘要 |
PROBLEM TO BE SOLVED: To provide a finder optical system which offers high observation magnification while maintaining high optical performance, a sufficiently long eye relief and sufficiently large eye relief diameter, and comfort of use, and to provide an image capturing device having the same.SOLUTION: A finder optical system is for observing an object image formed on a predefined plane by an image capturing optical system and comprises, in order from the predefined plane side to an observation side, an image reversing member for forming an erected image, a first lens group having a first lens and having negative refractive power, a second lens group having positive refractive power and having a second lens which is moved in an optical axis direction to adjust diopter, and a third lens group having positive or negative refractive power. The third lens group comprises, in order toward the observation side, a third lens having positive refractive power and a fourth lens having negative refractive power. The third lens satisfies a conditional expression: -1.9<(G3Ro+G3Re)/(G3Ro-G3Re)<-1.1, where G3Ro and G3Re represent curvature radius of an object side surface and that of an observation side surface, respectively. The fourth lens is biconcave. |
