| 摘要 |
A zoom lens system includes, in order from the object side to the image side, first, second, third, fourth lens units respectively having positive, negative, positive, and positive refractive powers. The lens units move from a wide-angle end to a telephoto end such that intervals between adjacent lens units vary during zooming. The first lens unit consists of first-a and first-b lens elements respectively having negative and positive refractive powers, and the second lens unit consists of second-a, second-b, and second-c lens elements respectively having negative, negative, and positive refractive powers. n12 and &ngr;12 respectively represent the refractive index and the Abbe number of the first-b lens element, and fw and ft respectively present the focal length at the wide-angle end and the telephoto end of the zoom lens system. Values for at least n12, &ngr;12, fw and ft are appropriately set based on predetermined conditions. |
