| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephotographic lens which is made compact in the overall length of the lens. SOLUTION: The telephotographic lens 1 consists of a first lens group G1 of positive refracting power, a second lens group G2 of negative refracting power and a third lens group G3. The lens group G1 comprises meniscus positive lenses 11 to 13 of≥70 in Abbe number with their convex surfaces directed toward an object side. The second lens group G2 comprises two sets of cemented lenses. When the focal length of the first lens group G1 is defined as f<SB>1</SB>, the focal length of the second lens group G2 as f<SB>2</SB>, and the focal length of the entire system as f, the telephotographic lens 1 satisfies the condition equations 1) 1.0<f<SB>1</SB>/|f<SB>2</SB>|<2.0 and 2) 3.5<f/|f<SB>2</SB>|<10. COPYRIGHT: (C)2003,JPO
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