PROBLEM TO BE SOLVED: To obtain a soft focus effect in photographing from distant view photographing such as a landscape to portrait photographing by satisfying a specified conditional expression in a lens system performing zooming by changing the axial distances of a front group, a middle group and a rear group. ;SOLUTION: Zooming is performed by moving all the lens groups, that is, the front group I, the middle group II and the rear group III while changing the axial distances between the front group I and the middle group II and between the middle group II and the rear group III in the case of zooming. The lens system satisfies a conditional expression I: SAU/fw-0.10, a conditional expression II: 0.30D23w/fw and a conditional expression III: 0.25D12t/ft. Provided that SAU is spherical aberration value at a focal distance where the spherical aberration is restrained to be minimum at an open aperture S, (fw) is the focal distance of an entire lens system at a short focal distance end, D23w is the axial distance between the surface of the middle group on an image side and the surface of the rear group on an object side at the short focal distance end, D12t is the axial distance between the surface of the front group on the image side and the surface of the middle group on the object side at a long focal distance end and (ft) is the focal distance of the entire lens system at the long focal distance end.;COPYRIGHT: (C)2000,JPO
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