| 摘要 |
PROBLEM TO BE SOLVED: To provide a small zoom lens having a vibration control function, long back focusing suitable for a digital single-lens reflex camera, a zoom ratio of about 10X and a field angle of 70°or more in a wide angle end state. SOLUTION: The zoom lens has a positive first lens group G1, a negative second lens group G2, a positive third lens group G3 and a positive fourth lens group G4 in this order from the object side and changes mutual spacing of the lens groups to vary magnification. The third lens group comprises a positive front group G3F and a negative rear group G3R in this order from the object side, and the displacement of an imaging position is corrected by moving only the rear group G3R in a direction orthogonal to an optical axis. At least one lens surface in the rear group G3R is a non-spherical surface shaped to increase positive refractive power or reduce negative refractive power toward the circumference from the optical axis in comparison with a spherical surface having a paraxial curvature radius, and satisfies a predetermined conditional expression. COPYRIGHT: (C)2009,JPO&INPIT
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