| 摘要 |
A zoom lens system includes a first to a third lens groups. Upon zooming, the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases. Each lens group is positioned closest to the object at the long focal length extremity. The third lens group includes first and second sub-lens groups. The first sub-lens group with at least one aspherical surface is positioned at the object-side end a reference distance, and the negative second sub-lens group is positioned at the image-side end thereof. The zoom lens system satisfies the following conditions: 1.7<fw/f3<2.5 . . . (1); -0.5<fw/f3b<-0.2 . . . (2); -45<DeltaIasp<-20 . . . (3); wherein, fw: the focal length of the entire zoom lens system at the short focal length extremity; f3: the focal length of the third lens group at the short focal length extremity; f3b: the focal length of the first sub-lens group at the short focal length extremity; and DeltaIasp: the aberration coefficients of the for the aspherical-surface terms with respect to the third-order aberration coefficients of the aspherical surface under the condition that the focal length of the entire lens system at the short focal length extremity is converted to 1.0.
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