| 主权项 |
1. A zoom lens comprising, in an order from an object side to an image surface side:
a first lens group having positive refractive power and comprising a negative lens and a positive lens; a second lens group having negative refractive power and comprising a negative lens having a meniscus shape concave toward the image surface side; a third lens group having positive refractive power and comprising an aspherical lens having at least one aspherical surface; and a fourth lens group having positive refractive power, wherein, during zooming from a wide angle position to a telephoto position, the first through fourth lens groups all move, the third lens group moves from the image surface side to the object side and then back to the image surface side, and the zoom lens satisfies the following conditions:
60≦Vd3; and2.9≦f4/fw≦5.6, wherein Vd3 denotes an Abbe's number of the aspherical lens of the third lens group, f4 denotes a focal length of the fourth lens group, and fw denotes a total focal length of the zoom lens in the wide angle position. |
