| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a zoom lens whose entire lens system is compact and in which high optical performance is obtained in the entire zoom range. <P>SOLUTION: The zoom lens is made up of 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 sequentially from an object side to an image side, in which each lens group moves such that a distance between the first lens group and the second lens group becomes smaller and a distance between the second lens group and the third lens group becomes larger in zooming from a wide angle end to a telephoto end. The conditional expressions below are satisfied when a focal length of the entire system in the telephoto end is ft, a focal length of the first lens group is f1, and an average value of the refractive index of material of all positive lenses included in the entire system is Npa: 0.35<¾f1¾/ft<0.55, and 1.80<Npa. <P>COPYRIGHT: (C)2012,JPO&INPIT |
