| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens system having a three-group structure of a negative lens-lead type and a zoom ratio of approximately 3 to 4 with suitably corrected aberrations, and covering a zooming range from the wide-angle extremity to the telephoto extremity. SOLUTION: In the zoom lens system including a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power, from an object-side in order, wherein the entire lens groups are moved, the first lens group includes three lenses, i.e. a first-1 lens having negative refractive power, a first-2 lens having negative and weak refractive power and at least one aspherical surface, and a first-3 lens having positive refractive power, from the object-side in order, wherein the zoom lens system satisfies the following condition (1): 0.5<(ra-rb)/(ra+rb)<1.2 where ra designates the radius of curvature of the object-side surface of the first-2 lens in the first lens group; and rb designates the radius of curvature of the image-side surface of the first-2 lens in the first lens group. COPYRIGHT: (C)2010,JPO&INPIT |
