| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a zoom lens able to satisfactorily correct various aberrations while achieving reductions in size and weight, a wider angle and a higher magnification. <P>SOLUTION: The zoom lens comprises, in order from an object side, a first group that has a positive refractive power and does not move for varying power, a second group that has a negative refractive power and moves for varying power, a third group that has a positive refractive power and moves for varying power, and a fourth group that has a positive refractive power and does not move for varying power. The first group has a 1a-th group that does not move for focusing, and a 1b-group that has a positive refractive power and moves for focusing. The 1a-th group is composed of three lenses that have negative, positive, and positive refractive powers. If the curvature radius of the image-side face of the negative lens of the 1a-th group is R12, the curvature radius of the object-side face of the object-side positive lens of the 1a-th group is R21, the focal distance of the first group is f1, and the focal distance of the tele-photo end of the zoom lens is ft, all of them are appropriately set. <P>COPYRIGHT: (C)2013,JPO&INPIT |
