| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens system which obtains a sufficient brightness and has satisfactorily corrected various aberrations such as a coma aberration, a spherical aberration, and a distortion aberration, while utilizing the merit that a mechanical mechanism is simple, in a negative-positive two-group zoom lens system.SOLUTION: The zoom lens system comprises a negative first lens group and a positive second lens group. When varying power from a wide-angle end to a telephoto end, an interval between the first lens group and the second lens group is decreased. The second lens group comprises a positive second A lens group and a positive second B lens group. The second A lens group includes two or more positive lenses and one or more negative lenses. The second B lens group includes one or more positive lenses and two or more negative lenses. The zoom lens system satisfies the following conditional expressions (1) and (2): (1)-1.0<f1/f2<-0.7 and (2)0.25<f2A/f2B<1.0, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f2A is the focal length of the second A lens group, and f2B is the focal length of the second B lens group. |
