| 摘要 |
The invention relates to a zoom lens system having stable performance and a high magnification, which comprises a first lens group G1 having positive refracting power, a second lens group G2 having negative refracting power, a third lens group G3 having positive refracting power and a fourth lens group G4 having negative refracting power. For zooming from a wide-angle end to a telephoto end of a zooming area having a continuous zooming action, an intergroup space of each lens group is varied. At least one group of the four lens groups is moved to define an extended wide-angle point SW that is a discontinuous zooming point at a position where a focal length thereof becomes shorter than the wide-angle end of the zooming area. At least one lens group of the four lens groups is moved to define an extended telephoto point ST that is a discontinuous zooming point at a position where a focal length thereof becomes longer than the telephoto end of the zooming area.
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