| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system which performs focusing without changing the entire length of the optical system, has a wide angle of view, is bright and compact, can perform focusing by moving small number of lenses, and achieves high performance.SOLUTION: In an optical system of an imaging lens, the number of lens elements constituting the entire optical system is seven or less. The optical system includes, in order from the object side to the image plane side, a positive first lens group Gr1, a positive second lens group Gr2, and a negative third lens group Gr3. The first lens group Gr1 comprises one or more negative lenses and one or more positive lenses. The second lens group Gr2 comprises one negative lens and one positive lens. The third lens group Gr3 comprises one negative lens. An aperture diaphragm AD is provided in the first lens group Gr1. The second lens group Gr2 serves as a focusing lens, and a focusing operation from an infinity side to a short distance side is performed by moving the second lens group Gr2 from the image plane side to the object side. |
