Zoom lens system

Claim 2

A zoom lens system comprising a front lens group having negative refractive power and a rear lens group having positive refractive power, said rear lens group consisting of a positive lens component, a positive meniscus lens component having a convex surface on the object side, a positive meniscus cemented doublet composed of a biconvex lens element and a biconcave lens element, a negative lens component and a positive lens component, said zoom lens system being so adapted as to perform zooming by varying the airspace reserved between said front and rear lens groups, and to satisfy the following conditions (1) and (2): 0.47<r.sub.15 /f.sub.R <0.53 (1) 0.1<n.sub.7 -n.sub.6 ( 2) wherein the reference symbol r 15 represents radius of curvature on the image side surface of the negative lens element arranged in said rear lens group, the reference symbols n 6 and n 7 designate refractive indices of both the lens elements respectively of the positive meniscus cemented doublet arranged in said rear lens group and the reference symbol f R denotes focal length of said rear lens group.

Claim 3

A zoom lens system according to claim 1 satisfying the following additional conditions (3) through (7): 1.1<|f.sub.F |/f.sub.T <1.24 (3) 2.15<f.sub.6 /f.sub.R <3.2 (4) 0.3<D/f.sub.R <0.6 (5) 10<ν.sub.6 -ν.sub.7 <25 (6) 50<ν.sub.4, ν.sub.5, ν.sub.6 ( 7) wherein the reference symbol D represents distance as measured from the object side surface of the positive meniscus cemented doublet to the image side surface of the positive lens component arranged on the extreme image side, the reference symbols ν 4 , ν 5 , ν 6 and ν 7 denote Abbe's numbers of the object side positive lens component, positive meniscus lens component and both the lens elements of the positive meniscus cemented doublet respectively arranged in said rear lens group, the reference symbol f 6 represents focal length of the positive meniscus cemented doublet arranged in said rear lens group, the reference symbol f F designates focal length of said front lens group and the reference symbol f T denotes focal length of said zoom lens system as a whole at its tele position.

Claim 4

A zoom lens system according to claim 2 wherein said front lens group consists of a negative meniscus lens component, a negative lens component and a positive lens component.

Claim 5

A zoom lens system according to claim 3 having the following numerical data: ______________________________________ f = 36˜67.9 F/2.8 ______________________________________ r.sub.1 = 94.018 d.sub.1 = 2.5 n.sub.1 = 1.72 ν.sub.1 = 50.25 r.sub.2 = 29.091 d.sub.2 = 9.8 r.sub.3 = -90.085 d.sub.3 = 1.8 n.sub.2 = 1.757 ν.sub.2 = 47.87 r.sub.4 = 76.554 d.sub.4 = 2.46 r.sub.5 = 59.156 d.sub.5 = 6.0 n.sub.3 = 1.8061 ν.sub.3 = 40.95 r.sub.6 = -124.841 d.sub.6 = 56.288˜1.116 r.sub.7 = 43.763 d.sub.7 = 6.0 n.sub.4 = 1.62041 ν.sub.4 = 60.27 r.sub.8 = 624.786 d.sub.8 = 0.1 r.sub.9 = 48.749 d.sub.9 = 4.0 n.sub.5 = 1.62041 ν.sub.5 = 60.27 r.sub.10 = 122.376 d.sub.10 = 3.5 r.sub.11 = 37.221 d.sub.11 = 7.5 n.sub.6 = 1.62041 ν.sub.6 = 60.27 r.sub.12 = -42.933 d.sub.12 = 1.55 n.sub.7 = 1.757 ν.sub.7 = 47.87 r.sub.13 = 93.708 d.sub.13 = 2.83 r.sub.14 = -160.760 d.sub.14 = 1.53 n.sub.8 = 1.7552 ν.sub.8 = 27.51 r.sub.15 = 26.176 d.sub.15 = 4.81 r.sub.16 = 239.203 d.sub.16 = 4.5 n.sub.9 = 1.7859 ν.sub.9 = 44.18 r.sub.17 = -42.526 f.sub.F = -82.398 f.sub.R = 51.535 f.sub.6 = 156.856 ______________________________________ wherein the reference symbol f represents focal length of said zoom lens system as a whole, the reference symbols r 1 through r 17 designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 16 denote thicknesses og the respective lens elements and airspaces reserved therebetween, the reference symbols n 1 through n 9 represent refractive indices of the respective lens elements and the reference symbols ν 1 through ν 9 designate Abbe's numbers of the respective lens elements.

Claim 6

A zoom lens system according to claim 3 having the following numerical data: ______________________________________ f = 36˜67.9 F/2.8 ______________________________________ r.sub.1 = 78.466 d.sub.1 = 2.5 n.sub.1 = 1.713 ν.sub.1 = 53.84 r.sub.2 = 28.534 d.sub.2 = 9.8 r.sub.3 = -98.909 d.sub.3 = 1.8 n.sub.2 = 1.757 ν.sub.2 = 47.87 r.sub.4 = 71.192 d.sub.4 = 2.47 r.sub.5 = 56.254 d.sub.5 = 6.0 n.sub.3 = 1.8044 ν.sub.3 = 39.58 r.sub.6 = -166.469 d.sub.6 = 55.874˜2.543 r.sub.7 = 41.962 d.sub.7 = 4.0 n.sub.4 = 1.6228 ν.sub.4 = 57.06 r.sub.8 = 390.264 d.sub.8 = 0.1 r.sub.9 = 47.444 d.sub.9 = 4.0 n.sub.5 = 1.62041 ν.sub.5 = 60.27 r.sub.10 = 131.106 d.sub.10 = 3.5 r.sub.11 = 38.063 d.sub.11 = 7.5 n.sub.6 = 1.6223 ν.sub.6 = 53.2 r.sub.12 = -54.587 d.sub.12 = 1.55 n.sub.7 = 1.7495 ν.sub.7 = 35.27 r.sub.13 = 92.907 d.sub.13 = 2.86 r.sub.14 = -103.514 d.sub.14 = 1.53 n.sub.8 = 1.7552 ν.sub.8 = 27.51 r.sub.15 = 25.836 d.sub.15 = 4.76 r.sub.16 = 188.291 d.sub.16 = 4.5 n.sub.9 = 1.834 ν.sub.9 = 37.16 r.sub.17 = -44.375 f.sub.F = -80.917 f.sub.R = 50.589 f.sub.6 = 146.215 ______________________________________ wherein the reference symbol f represents focal length of said zoom lens system as a whole, the reference symbols r 1 through r 17 designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 16 denote thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n 1 through n 9 represent refractive indices of the respective lens elements and the reference symbols ν 1 through ν 9 designate Abbe's numbers of the respective lens elements.

Claim 7

A zoom lens system according to claim 3 having the following numerical data: ______________________________________ f = 36˜67.9 F/2.8 ______________________________________ r.sub.1 = 84.606 d.sub.1 = 2.4 n.sub.1 = 1.72 ν.sub.1 = 41.98 r.sub.2 = 28.958 d.sub.2 = 10.3 r.sub.3 = -99.294 d.sub.3 = 1.5 n.sub.2 = 1.713 ν.sub.2 = 53.84 r.sub.4 = 77.358 d.sub.4 = 2.50 r.sub.5 = 6.0 d.sub.5 = 6.0 n.sub.3 = 1.8044 ν.sub.3 = 39.58 r.sub.6 = -202.633 d.sub.6 = 55.037˜0.950 r.sub.7 = 89.584 d.sub.7 = 4.0 n.sub.4 = 1.62041 ν.sub.4 = 60.27 r.sub.8 = -199.000 d.sub.8 = 0.1 r.sub.9 = 34.003 d.sub.9 = 4.0 n.sub.5 = 1.617 ν.sub.5 = 62.79 r.sub.10 = 94.166 d.sub.10 = 5.0 r.sub.11 = 40.259 d.sub.11 = 7.5 n.sub.6 = 1.62041 ν.sub.6 = 60.27 r.sub.12 = -50.000 d.sub.12 = 1.36 n.sub.7 = 1.757 ν.sub.7 = 47.87 r.sub.13 = 109.866 d.sub.13 = 2.51 r.sub.14 = -197.478 d.sub.14 = 1.30 n.sub.8 = 1.7552 ν.sub.8 = 27.51 r.sub.15 = 25.877 d.sub.15 = 4.50 r.sub.16 = 800.289 d.sub.16 = 4.83 n.sub.9 = 1.7859 ν.sub.9 = 44.18 r.sub.17 = -40.588 f.sub.F = -82.196 f.sub.R = 50.421 f.sub.6 = 152.821 ______________________________________ wherein the reference symbol f represents focal length of said zoom lens system as a whole, the reference symbols r 1 through r 17 designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 16 denote thickneeses of the respective lens elements and airspaces reserved therebetween, the reference symbols n 1 through n 9 represent refractive indices of the respective lens elements and the reference symbols ν 1 through ν 9 designate Abbe's numbers of the respective lens elements.

Claim 8

A zoom lens system according to claim 3 having the following numerical data: ______________________________________ f = 36˜67.9 F/2.8 ______________________________________ r.sub.1 = 85.032 d.sub.1 = 2.37 n.sub.1 = 1.72 ν.sub.1 = 50.25 r.sub.2 = 28.635 d.sub.2 = 9.8 r.sub.3 = -123.743 d.sub.3 = 1.71 n.sub.2 = 1.757 ν.sub.2 = 47.87 r.sub.4 = 70.097 d.sub.4 = 2.91 r.sub.5 = 55.979 d.sub.5 = 6.0 n.sub.3 = 1.8044 ν.sub.3 = 39.58 r.sub.6 = -230.909 d.sub.6 = 50.771˜1.057 r.sub.7 = 156.575 d.sub.7 = 5.5 n.sub.4 = 1.62041 ν.sub.4 = 60.27 r.sub.8 = -207.315 d.sub.8 = 0.1 r.sub.9 = 36.804 d.sub.9 = 3.86 n.sub.5 = 1.62041 ν.sub.5 = 60.27 r.sub.10 = 213.479 d.sub.10 = 3.38 r.sub.11 = 36.804 d.sub.11 = 7.5 n.sub.6 = 1.62041 ν.sub.6 = 60.27 r.sub.12 = -45.120 d.sub.12 = 1.51 n.sub.7 = 1.757 ν.sub.7 = 47.87 r.sub.13 = 129.016 d.sub.13 = 3.62 r.sub.14 = 3329.514 d.sub.14 = 1.48 n.sub.8 = 1.7847 ν.sub.8 = 26.22 r.sub.15 = 24.486 d.sub.15 = 5.00 r.sub.16 = -612.618 d.sub.16 = 4.34 n.sub.9 = 1.8044 ν.sub.9 = 39.58 r.sub.17 = -42.041 f.sub.F = -76.541 f.sub.R = 49.586 f.sub.6 = 114.580 ______________________________________ wherein the reference symbol f represents focal length of said zoom lens system as a whole, the reference symbols r 1 through r 17 designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 16 denote thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n 1 through n 9 represent refractive indices of the respective lens elements and the reference symbols ν 1 through ν 9 designate Abbe's numbers of the respective lens elements.