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Document Number
US Patent 7031080
Issued Date
April 18, 2006
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Inventors
Koike; Kazumi (Minami-Ashigara,JP)
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Abstract
A photographic lens has a first and second positive lens. The first lens is a meniscus lens having a convex object side surface. The second lens is a double-convex lens. The photographic lens satisfies the following conditions: 5.6.ltoreq.f<8; F1>F2; 0.39<F/F1.ltoreq.0.5; 0.15<R1/F<0.19; 1.4<(F/R3)f.ltoreq.3.0; and R3>|R4| wherein F is an overall focal length, F1 is a focal length of the first lens, F2 is a focal length of the second lens, f is a ratio of the overall focal length F to an effective aperture size defined by the first stop, R1 is a radius of curvature of the object side surface of the first lens, R3 and R4 are radii of curvature of the object side spherical surface and of an average spherical surface of the image side aspherical surface of the second lens.
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Number of Claims:
4
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Published
April 18, 2006
Application Number
10/921,919
Filed
August 20, 2004
US Classification
359/794   359/717 359/740
Int'l Classification
G02B   9/06   (20060101)  
Attorney/Law Firm
Priority Data
Aug 20, 2003 [JP] 2003-208052
USPTO Field of Search
359/793   359/794   359/740   359/717  
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