| 摘要 |
A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. Upon zooming from the short focal length extremity to the long focal length extremity, each of the first to third lens groups move along the optical axis. The first lens group includes a negative first sub-lens element, a second sub-lens element having a weak negative refractive power and at least one aspherical surface, and a positive third sub-lens element. The zoom lens system satisfies the condition, 0.5<(ra−rb)/(ra +rb)<1.2  (1), where ra designates the radius of curvature of the object-side surface of the second sub-lens element and rb designates the radius of curvature of the image-side surface of the second sub-lens element.
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