| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens whose Petzval sum is excellent, and which can be constituted to be compact while excellently adjusting aberration performance. SOLUTION: Assuming that the synthetic focal distances of a 1st lens group 11, a 2nd lens group 12, a 3rd lens group 13 and a 4th lens group 14 are f1, f2, f3 and f4 respectively, the synthetic focal distance of an entire system at a wide end is (fw), and the refractive indexes on a d-line of the second, the third and the fourth lenses counted from an object side are n2, n3 and n4 respectively, relations of 4.0<¾f1/fw¾<5.0, 0.75<¾f2/fw¾<0.85, 2.5<¾f3/fw¾<3.0, 2.0<¾f4/fw¾<3.0, n2>1.7, 1.65<n3<1.76 and n4>1.85 are satisfied. COPYRIGHT: (C)2004,JPO |
