| 摘要 |
A zoom lens system includes, in order from object-side to image-side a positive first lens unit, a second negative lens unit, a third lens unit, and a fourth positive lens unit. The fourth unit includes a front subunit having positive power and a rear subunit having positive power. The following conditions are satisfied: -2.100×10-3×nud+0.693<thetagF; 0.555<thetagF<0.900; 0.8<(nufp/nufn)/(nurp/nurn)<4.0; 0.8<|{(thetafn-thetafp)/(nufp-nufn)}/{(thetarn-thetarp)/(nurp-nurn)}|, where vd and thetagF indicate Abbe number and partial dispersion ratio of a lens included in the rear subunit, respectively, and where nufp, thetafp, nufn and thetafn indicate averages of Abbe number and partial dispersion ratio of positive lenses and averages of Abbe number and partial dispersion ratio of negative lenses included in the front subunit, respectively; nurp, thetarp, nurn and thetarn indicate averages of Abbe number and partial dispersion ratio of positive lenses and averages of Abbe number and partial dispersion ratio of negative lenses included in the rear subunit, respectively.
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