| 摘要 |
The invention discloses a macro lens that takes a retrofocusing function for the purpose of downsizing. The macro lens employs a floating mechanism to cover a wide photographing range from the equi-magnification to the infinity, and especially, attains a great imaging performance by appropriately compensating for spherical aberration, comatic aberration, and chromatic aberration of magnification. The macro lens comprised of first to fifth lenses in the order closer to the object; that is, the first lens serving as a negative meniscus lens with a convex surface oriented to the object, the fourth lens as a negative lens with a concave surface of great curvature oriented to the image plane, and the fifth lens as a negative lens with a surface of great curvature oriented to the object. The macro lens satisfies conditions as expressed in the following formulae: <?in-line-formulae description="In-line Formulae" end="lead"?>0.6<=F1/F<=1.3 (1)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>0.9<=F4/F5<=1.5 (2)<?in-line-formulae description="In-line Formulae" end="tail"?> where F is a focal length of the entire lens system, F1 is a focal length of the first lens, F4 is a focal length of the fourth lens, and F5 is a focal length of the fifth lens.
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