| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system that is compact and lightweight, generates little flare, and is well corrected for magnification chromatic aberration.SOLUTION: An optical system comprises a positive first group L1, negative second group L2, and negative third group L3, where the first group has a diffractive optical element, the second group is used for focusing, and the third group comprises a 3a group L3a on the object side and a 3b group L3b on the image side with a largest air gap therebetween. The optical system satisfies conditional expressions below, where f represent a focal length of the entire system, f1 represents a focal length of the first group, f2i represents a focal length of an i-th lens of the second group, f3bi represents a focal length of an i-th lens of the 3b group, vd2i represents an Abbe number of a material of the i-th lens of the second group, and vd3bi represents an Abbe number of a material of the i-th lens of the 3b group.SELECTED DRAWING: Figure 1 |
