| 摘要 |
The present invention is directed to providing a large aperture telephotographing zoom lens that employs an inner-focusing system to enable quick focusing and avoid a great aberration when the zoom lens renders the close object in focus. The zoom lens comprises at least five groups of lens pieces arranged in series, namely, the foremost or first lens group of positive refractivity positioned the closest to the object, the succeeding second lens group of negative refractivity, the third lens group of negative refractivity, the fourth lens group of positive refractivity, and the rearmost or fifth lens group of positive refractivity. During varying the magnification for zooming in a transition from the wide-angle end to the telephoto end, all the lens pieces of the second, third, and fourth lens groups are moved toward the image plane, and the third lens group alone is displaced for focusing.
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