| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-performance large-viewing angle large-diameter imaging optical system which has a half viewing angle of 38 degrees or more and an F number of 2.0 or less and is suitably applicable to an image pickup element with 10,000,000-20,000,000 pixels. SOLUTION: The imaging optical system is a single-focus imaging optical system constructed of an aperture stop S, a first lens group G1, and a second lens group G2. The first lens group includes a first F lens group and a first R lens group arranged at the widest air space in the first lens group. The first F lens group includes two negative lenses, and the first R lens group includes one positive lens. The second lens group G2 includes a second F lens group and a second R lens group. The second F lens group, wherein a first positive lens, a first negative lens, a second negative lens, and a second positive lens are arranged, has positive power, and the second negative lens and the second positive lens are joined together as a positive cemented lens. The second R lens group has one lens. A focal distance f of the whole system, a focal distance f1 of the first lens group, a focal distance f2 of the second F lens group, and a focal distance f3 of the second R lens group satisfy conditions (1), (3), and (4). COPYRIGHT: (C)2011,JPO&INPIT |
