| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain a zoom lens having a wide field angle, a high zoom ratio, and high optical performance over the entire zoom range. <P>SOLUTION: The zoom lens includes, in order from an object side to an image side, a first lens group having positive refractive power which is immovable for zooming, a second lens group for variable power having negative refractive power, a third lens group for variable power having negative refractive power, a fourth lens group having positive refractive power which corrects variation of an image plane associated with variable power, and a fifth lens group having positive refractive power which is immovable for zooming. The second lens group moves to the image side during zooming from a wide angle end to a telephoto end, while the third lens group moves to draw a convex trajectory toward the object side. A focal length fw of the entire system at the wide angle end, a zoom ratio Z, and a focal length fz of the entire system at a zoom position where the third lens group is located closest to the object side are each properly set. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
