| 摘要 |
The improved zoom lens system comprises, in order from the object side, a negative first lens group to maintain a constant focal position, a positive second lens group to control zooming, and a negative third lens group to operate as a relay lens unit. The third lens group moves towards the object during zooming from the wide-angle position to the middle-angle position and towards the image plane during zooming from the middle-angle position to the narrow-angle position. This three-group lens system is compact in overall size and can suppress the aberrational variations associated with zooming.
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