| 摘要 |
A zoom lens system including, 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 units, in which: 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×&ngr;d+0.693<&thetas;gF, 0.555<&thetas;gF<0.900, where &ngr;d and &thetas;gF indicate Abbe number and partial dispersion ratio of a lens included in the rear subunit, respectively; 0.8<(&ngr;fp/&ngr;fn)/(&ngr;rp/&ngr;rn)<4.0, 0.8<|{(&thetas;fn−&thetas;fp)/(&ngr;fp−&ngr;fn)}/{(&thetas;rn−&thetas;rp)/(&ngr;rp−&ngr;rn)}|, where &ngr;vp, &ngr;vp, &ngr;vn and &thetas;fn 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; &ngr;rp, &thetas;rp, &ngr;rn and &thetas;rn 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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