| 摘要 |
In a zoom lens system having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power and a fourth lens group of positive refractive power and including a wide angle of view of 70 DEG or more and having a wide magnification change range of a zoom ratio of four times or more, when zooming is effected from the wide angle end to the telephoto end, the first lens group and the fourth lens group are moved linearly on the optic axis toward the object side, and the second lens group is moved nonlinearly on the optic axis in response to the movement of the first and fourth lens groups to maintain the image point constant, and relative to a linear movement locus passing through the position at the wide angle end of the magnification change range and the position at the telephoto end, the second lens group has a movement locus near to the image side from the wide angle end to the vicinity of the intermediate focal length state and has a nonlinear movement locus near to the object side from the vicinity of the intermediate focal length state to the telephoto end.
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