| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact zoom lens having a half field angle of 38°or more at a wide angle end, a variable power ratio of 6.5 times or more, a small number of lenses and a resolution corresponding to an imaging element of 10 to 15 million pixels. SOLUTION: The zoom lens includes, in order from an object side: a first positive lens group G1; a second negative lens group G2; a third positive lens group G3; and a fourth positive lens group G4. Accompanying variable power from a wide-angle end to a telephoto end, a distance between the first lens group G1 and the second lens group G2 increases, a distance between the second lens group G2 and the third lens group G3 decreases and a distance between the third lens group G3 and the fourth lens group G4 increases. In order from the object side, the first lens group G1 has a negative lens, a positive lens and a positive lens, the second lens group has a negative lens, a positive lens and a negative lens, the third lens group has a positive lens, a positive lens and a negative lens, and the fourth lens group has a positive lens, arranged respectively in order. The refractive index, Abbe's number and partial dispersion ratio of the positive lens composed of optical glass included in the first lens group G1 satisfy predetermined conditional expressions. COPYRIGHT: (C)2011,JPO&INPIT |
