| 摘要 |
PROBLEM TO BE SOLVED: To provide a long focus lens, selecting glass for eliminating thermal aberration to a large temperature change as the whole lens system while a fluophosphate glass is disposed in a position effective for correcting axial color aberration. SOLUTION: This long focus lens, from which thermal aberration is eliminated, includes: a first lens group G1, a second lens group G2 and a third lens group G3 which are disposed in order from an object side. The first lens group G1 is positive, the second lens group G2 is positive, the third lens group G3 is negative, the first lens group G1 positioned closest to the object includes three lenses disposed positive, negative and positive in order. The third lens group G3 positioned closest to an image includes at least one positive lens, and the first lens group G1 includes at least one lens satisfying a predetermined conditional expression. The at least one positive lens of the third group satisfies a predetermined conditional expression. COPYRIGHT: (C)2010,JPO&INPIT |
