| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens system with superior optical performance which offers quick and quiet focusing with a more compact and lighter focusing lens group and good correction for aberrations such as axial chromatic aberration and lateral chromatic aberration.SOLUTION: The zoom lens system comprises a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group arranged in order from the object side, where at least the second lens group and the third lens group move when zooming. The first lens group comprises a positive 1a lens group which is stationary while focusing and a positive 1b lens group which is a focusing lens group that moves while focusing arranged in order from the object side. The 1a lens group having at least one negative lens and the 1b lens group comprising a single positive lens satisfy conditional expressions (1) and (2): (1) 60<&ngr;d1b<75, (2) &ngr;d1a<24; where &ngr;d1b represents an Abbe number of the single positive lens of the 1b lens group, and &ngr;d1a represents an Abbe number(s) of the at least one negative lens of the 1a lens group. |
