| 摘要 |
A zoom lens system comprising a first lens group having positive refractive power and having a focusing function, a second lens group having negative refractive power and having a vari-focal function, a third lens group having positive refractive power and having a vari-focal function, and a fourth lens group having positive refractive power and having a vari-focal function, wherein the second lens group comprises a negative lens having a surface with strong curvature on the image side, a cemented doublet consisting of a negative lens and a positive lens, a negative lens having a surface with strong curvature on the object side, and a positive meniscus lens having a surface with strong curvature on the object side, the zoom lens system having a large vari-focal ratio and a large aperture ratio and arranged compactly.
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