| 摘要 |
In the compact zoom lens disclosed, a first lens group of positive power includes a negative lens and two positive lenses movable for focusing, a second lens group has a negative refractive power, a positive third lens group has a positive lens and a negative lens, with the image magnification variation being effected by the second and third lens groups, a positive fourth lens group constitutes an image forming section. The relations 72< nu 23<95.1 1x10-3<( theta 1- theta 23)/( nu 23- nu 1)<2x10-3 0.9x10-3<( theta 9- theta 8)/( nu 8- nu 9)<2.3x10-3 are satisfied for correcting chromatic aberration in the telephoto position. Here, nu 23 is the average value of the Abbe numbers of the two positive lenses in the first lens group nu 1 of the negative lens in the first lens groups, theta 23 the average value of the partial dispersion ratios of two positive lenses in the first lens groups, theta 1 the partial dispersion ratio of the negative lens in the first lens group, and nu 8, nu 9, theta 8, and theta 9 the Abbe numbers and partial dispersion ratios of the positive and negative lenses in the third lens group.
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