| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens having high optical performance all over the object distance. SOLUTION: The zoom lens includes, in order from an object side to an image side, a first lens group that does not move during zooming and has positive refractive power, a second lens group that performs variable power and has negative refractive power, a third lens group that corrects image plane variation caused by variable power and has negative refractive power, and a fourth lens group that does not move during zooming and has positive refractive power. The first lens group has an eleventh lens group that does not move during focusing and has negative refractive power, a twelfth lens group that moves along an optical axis during focusing and has positive refractive power, and a thirteenth lens group that does not move during focusing and has positive refractive power, and at least one lens surface AS12 in the twelfth lens group is aspherical. As for the aspherical shape, positive refractive power becomes weaker toward the periphery part of the lens from the center of the lens when the lens surface AS12 is a positive refractive surface, and negative refractive power becomes stronger toward the periphery part of the lens from the center of the lens when the lens surface AS12 is a negative refractive surface. COPYRIGHT: (C)2009,JPO&INPIT
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