| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a zoom lens which has a variable power ratio of 4 times or more even though a half angle of view at the wide angle end is 38 degrees or more and is sufficiently wide, has aberrations sufficiently corrected, and has a resolving power adapted to a small-sized image pickup device having a high resolution. <P>SOLUTION: The zoom lens includes, in order from an object side to an image side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. During zooming from the wide angle end to the telephoto end, the first lens group G1 moves along a locus convex toward the image side, the second lens group G2 moves toward the object side, and the third lens group G3 moves. The zoom lens satisfies the following conditional expressions (1), (2), and (3): (1) 2.2<F1p/¾F1¾<2.8, (2) Ft/Fw>4, and (3)ωw>38°, where F1p is a focal length of a positive lens L2 in the first lens group G1, F1 is a composite focal length of the first lens group G1, Fw is a focal length at the wide angle end, Ft is a focal length at the telephoto end, andωw is a half angle of view at the wide angle end. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
