| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a zoom lens which has a long back focus, locates the exit pupil away from an image surface, causes less white shading and obtains an image of high image quality. <P>SOLUTION: The zoom lens includes: a front group including a lens group which moves sequentially from the object side to the image side when zooming, an aperture diaphragm, and a rear group having positive refractive power fixed when zooming. The rear group includes a front lens group having the positive refractive power on the object side with the longest air space between the front lens group and a rear lens group, and the rear lens group having the positive refractive power on the image side, while the rear lens group includes a lens s1 having negative refractive power positioned closest to the object side, and a lens s3 having the negative refractive power positioned closest to the image side, and a focal distance frr of the rear lens group, and focal focuses fs1 and fs3 of the lenses s1 and s3 are respectively and appropriately set. <P>COPYRIGHT: (C)2012,JPO&INPIT |
