| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens in which image formation performance is improved, the size is reduced and the manufacturing is made easy and to provide an image pickup unit using the lens. SOLUTION: The zoom lens consists of a negative first lens group G1, a positive second lens group G2 and a positive third lens group G3 in that order from an object side and zooming is conducted by moving at least the groups G1 and G2. The group G2 is constituted of at least one positive lens 21, a cemented lens which is made of a negative lens 22 having a convex face on the object side and a positive lens 23 and a negative lens 24 having a concave face on the image surface side and satisfies the following conditional equations (1) 10<νd23≡νd22, (2) 0.05<Nd22-Nd23 and (3) 0.2<R27/f2<1. COPYRIGHT: (C)2004,JPO |
