| 摘要 |
A zoom lens comprises first and fourth units which don't move for zooming, and second and third units moved during zooming. The first unit includes a front side partial unit which don't move for focusing, a movable partial unit moved for focusing, and a rear side partial unit which don't move for focusing, the rear side partial unit includes positive lenses and one or more negative lenses, and the following conditions are satisfied: −1.2×10−3<(&thetas;pa−&thetas;n)/(&ngr;pa−&ngr;n), and &ngr;n<30, where &ngr;n is the smallest Abbe number of the material of the negative lenses, &thetas;n is the partial dispersion ratio of the material of the negative lens of the smallest Abbe number, &ngr;pa is the average of the Abbe numbers &ngr; of the materials of positive lenses, and &thetas;pa is the average of the partial dispersion ratio &thetas; of the materials of the positive lenses. |
