| 摘要 |
PROBLEM TO BE SOLVED: To obtain an eyepiece optical system made compact, capable of adjusting diopter in a wide field and having high optical performance, and a finder system having the same. SOLUTION: The eyepiece optical system includes a first lens group having negative refractive power and a second lens group having positive refractive power in order from an observing object side to an eye point side, and adjusts the diopter of a finder by moving the second lens group in an optical axis direction, wherein the first lens group has a positive lens and a negative lens, and the second lens group comprises one positive lens. When it is assumed that the focal distances of the first and the second lens groups are F1 and F2 respectively, the focal distances of the positive lens in the first lens group and the positive lens in the second lens group are f1p and f2p respectively, space between the positive lens and the negative lens in the first lens group is da, and a distance from the lens surface of the first lens group nearest to the eye point side to the lens surface of the second lens group nearest to the observing object side is db, the eyepiece optical system satisfies conditions 1.5<¾F1/F2¾<3 and 0<(f1p/f2p)×(da/db)<1. COPYRIGHT: (C)2007,JPO&INPIT
|
