| 摘要 |
PROBLEM TO BE SOLVED: To make a zoom lens which is used for a digital video camera and a digital still camera and has a variable power ratio of 2 to 3, small in size and low in cost without deteriorating image forming performance. SOLUTION: In the zoom lens of a three-group configuration, a 2nd lens group GR2 is composed of at least one lens L3 having positive refractive power and at least one doublet obtained by joining three lenses L4, L5 and L6 having negative, positive and negative refractive power respectively. When n(L4) is the refractive index of the lens L4 on a d-line, n(L5) is the refractive index of the lens L5 on the d-line, n(L6) is the refractive index of the lens L6 on the d-line andν(L6) is the Abbe number of the lens L6 on the d-line, they satisfy respective conditions -0.1<n(L4)-n(L5)<0.2, 1.45<n(L6)<1.60, and 55<ν(L6).
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