| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens suitable for a television camera having a large aperture, a wide angle and a high variable power ratio to such an extent that the variable power ratio is 12 to F-number is 1.7 by forming a lens surface so that it may be aspherical. SOLUTION: This zoom lens is provided with a lens V1 whose surface satisfying a condition 1.25<hw/ht and 1.32<hw/hz is formed to be aspherical. In the expressions, (ht) means the maximum incident height of axial luminous flux, (hw) means the maximum incident angle of off-axis luminous flux at the maximum angle of view at a wide-angle end, and (hz) means the maximum incident angle of the off-axis luminous flux at the maximum angle of view at zoom position in the variable power ratio of Z<1/4> . Besides, the zoom lens satisfies conditions 1.0<f21/f2<1.8, 1.8×10<3> <|Δ10/f2|<4.6×10<-2> , 7.7×10<-4> <|Δ9/f2<3.4×10<-2> and 1.0×10<-4> <|Δ7/f2|<1.7×10<-2> . In the expressions, f2 means the focal distance of a 2nd group V, f21 means the focal distance of the lens V1,Δ10,Δ9 andΔ7 mean the aspherical amount of 100%, 90% and 70% of the effective diameter of the lens, respectively.
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