| 摘要 |
PROBLEM TO BE SOLVED: To provide a macro lens which has compactness, excellent portability, and a wide focal length, is made shorter in the overall length of the lens and is prevented in the degradation in comatic aberrations by optimizing the focal length of a first lens group. SOLUTION: The macro lens comprises a front lens group of a retrofocus type composed, successively from an object side, of a first lens of a negative meniscus lens turning its convex face to the object side, a second lens and a third lens of a positive lens turning its surface of stronger curvature to the object side, a fourth lens of a negative lens having a concave surface of stronger curvature on an image plane side, further a fifth lens and sixth lens which are cemented lenses of a negative lens and positive lens turning their faces of the stronger curvature to the object side via an air spacing having a diaphragm, and a seventh lens of a positive lens turning its face of the stronger curvature to the image plane side and a rear lens group composed of an eighth lens of a negative lens and a ninth lens of a positive lens, wherein (1): 1.0< ¾F<SB>l</SB>¾/F<SB>t</SB><1.3, (2): 4.0<¾F<SB>r</SB>¾/F<SB>t</SB><6.0, where F<SB>1</SB>: the focal length of the first lens, F<SB>2</SB>: the focal length of the second lens, F<SB>t</SB>: the focal length of the entire system of the lens. COPYRIGHT: (C)2005,JPO&NCIPI
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