| 摘要 |
A compact, light-weight vari-focal lens system having a high vari-focal ratio, a high aperture ratio and comprising a small number of lens components. Said vari-focal lens system comprises a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power and a fourth lens unit having positive refractive power, said second and third lens units being shifted along the optical axis for varying focal length while varying the airspace reserved therebetween, said second lens unit consisting of a single concave lens component having an aspherical surface and said third lens unit consisting of a single positive lens component.
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