| 摘要 |
A zoom lens includes, in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. During change of magnification from a short focal end to a long focal end, the first lens group is fixed, the second lens group is moved to an image side, the third lens group is moved, and the fourth lens group is fixed. The first lens group and the fourth lens group include diffraction surfaces and satisfy the Condition Expressions 50<f1doe/f1<200 (1) and 100<f4doe/f4<300 (2). |
| 主权项 |
1. A zoom lens comprising, in order from an object side:
a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a negative refractive power; and a fourth lens group having a positive refractive power, wherein, during change of magnification from a short focal end to a long focal end, the first lens group is fixed, the second lens group is moved to an image side, the third lens group is moved, and the fourth lens group is fixed, wherein the first lens group and the fourth lens group include diffraction surfaces and satisfy the following Condition Expressions (1) and (2),
50<f1doe/f1<200 (1)100<f4doe/f4<300 (2) where f1doe denotes a focal length of the diffraction surface of the first lens group, f1 denotes a focal length of the first lens group, f4doe denotes a focal length of the diffraction surface of the fourth lens group, and f4 denotes a focal length of the fourth lens group. |
