| 摘要 |
PURPOSE:To correct satisfactorily an aberration of a frame image, and also to obtain a good distortion of a view field image, by making a shape of a concave reflection face an aspherical face determined by a specified equation. CONSTITUTION:A finder optical system is formed by objective lenses 11, 12 and an eyepiece 15 having a frame mark FM. Reflected light from the frame mark FM is reflected by a concave reflection face S of the objective lens 12 and travels to a pupil P. The concave reflection face S satisfies such relation as shown by the equation. Also, in the equation, the lower limit maintains an aspherical effect, corrects sufficiently an eyesight difference of the center and the circumference of a frame image face, and the upper limit not only reduces aberration of a view field image but also prevents that the eyesight of the circumference becomes too near due to a fact that the eyesight of the frame image face is corrected excessively. |
