Invention Grant
US09001433B2 Zoom lens and imaging apparatus 有权
变焦镜头和成像设备

Zoom lens and imaging apparatus
Abstract:
A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes a first lens subgroup having a negative power, which is fixed while focusing, a second lens subgroup having a positive power, which moves while focusing, and a third lens subgroup having a positive power, which is fixed while focusing. The second lens subgroup includes a positive lens having a surface having a radius of curvature with a smaller absolute value toward the image side; and a cemented lens constituted by a negative lens toward the object side and a positive lens toward the image side, cemented together at a joint surface having a convex surface toward the object side. The focal distance f12 of the second lens subgroup and the focal length fw of the entire system at the wide angle end satisfy the relationship: 3.0
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