| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens which is easy to assemble and compact, and has a wide viewing angle and a high variable power ratio, and whose aberration is satisfactorily corrected. <P>SOLUTION: The zoom lens includes: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power, and the movement of the four lens group varies power. The first lens group includes a negative lens and a positive lens. The second lens group includes a negative lens, a negative lens and positive lens. The third lens group includes a third a lens group having one positive lens and a third b lens group having a three-piece cemented lens having a positive lens, a negative lens and a positive lens. And, the following conditional expressions are satisfied; 0.1<n3b2-n3b1<0.7,0.1<n3b2-n3b3<0.7 where: n3b1 denotes the refractive power of the lens nearest to the object side in the third b lens group, corresponding to d-rays; n3b2 denotes the refractive power of the lens in the middle of the third b lens group, corresponding to d-rays; and n3b3 denotes the refractive power of the lens nearest to the image side in the third b lens group, corresponding to d-rays. <P>COPYRIGHT: (C)2012,JPO&INPIT |
