| 摘要 |
A zoom lens includes a first lens unit (positive), a second lens unit (negative), a third lens unit (positive), and a rear lens group having one or more lens units. During zooming from the wide-angle end to the telephoto end, the distance between the first and second lens units increases, the distance between the second and third lens units decreases, and the distance between the third lens unit and the rear lens group changes. The first lens unit consists of a positive lens and a negative lens. The following conditional expressions are satisfied: 8.0<f1/fW<30.0 and 2.0<&bgr;2T/&bgr;2W<10.0, where f1 is a focal length of the first lens unit, fW is a focal length of the entire system at the wide-angle end, and &bgr;2W and &bgr;2T are respectively lateral magnifications of the second lens unit at the wide-angle end and the telephoto end.
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