| 摘要 |
A zoom lens includes, in order from the object side, a first lens group of negative refractive power, and second and third lens groups, each of positive refractive power. The second lens group includes a stop on its object side. Each of the first and second lens groups includes negative and positive refractive power elements and at least two aspheric surfaces. The third lens group is a single lens component. All but one lens component may be a single lens element. When zooming from the wide-angle end to the telephoto end, the first and second lens groups move closer together while the second lens group moves farther from the third lens group. The third lens group moves for focusing but not for zooming. The zoom lens satisfies specified conditions which insure compactness of the zoom lens when not in use, high-speed focusing, favorable correction of various aberrations, and bright images.
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