| 摘要 |
PROBLEM TO BE SOLVED: To realize miniaturization, to obtain a high power variation range up to variable power ratio exceeding 6 and to make optical performance excellent all over the power variation area. SOLUTION: This zoom lens system is constituted of a 1st positive lens group, a 2nd negative lens group, a 3rd positive lens group, and a 4th positive lens group. The 2nd lens group consists of a 1st negative lens component, a 2nd negative lens component, a 3rd positive lens component and a 4th negative lens component; the 3rd lens group consists of a positive lens component nearest to an object side and a negative lens nearest to an image side; and the 4th lens group consists of a positive front group and a rear group having a positive lens and a negative lens forming a convex meniscus air lens in between. The lens system satisfies following conditions. (1) 0.16<|f2|/f1<0.23 (2) 5<h×z/ΔD34<27. Provided that f1 is the focal length of the 1st lens group, f2 is the focal length of the 2nd lens group, (h) is maximum image height on an image-formation surface, (z) is the variable power ratio from a wide-angle end to a telephoto end, andΔD34 is a difference between a distance between the 3rd lens group and the 4th lens group at the wide-angle end and that at the telephoto end.
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