Wide-angle zoom lens system

Claim 2

A wide-angle zoom lens system comprising a front negative lens group and rear positive lens group, said front negative lens group comprising a first, second and third lens components, said rear positive lens group comprising a fourth, fifth, sixth, seventh and eighth lens components, said first lens component being a negative lens, said second lens component having negative refractive power, said third lens component being a positive lens, said fourth lens component being a positive lens, said fifth lens component being a positive lens, said sixth lens component being a positive cemented doublet, said seventh lens component being a negative lens, said eighth lens component being a positive lens, said wide-angle zoom lens system being arranged to be zoomed by varying the airspace between said front negative lens group and said rear positive lens group and to satisfy the following conditions: (1) -2.0≦f F /f R ≦-1.45 (2) 1.0≦a/f F ≦1.5 (3) -1.2≦b/f R ≦-1.05 (4) 0.5≦f 1 /f F ≦0.95 (5) 1.0≦r 6 /f F ≦10 (6) 0.65≦f 456 /f R ≦1.0 (7) 0.45≦r 15 /f R ≦1.0 (8) 0.5≦f 8 /f R ≦1.1 (9) 50≦ν 1 wherein reference symbol f F represents the focal length of the front lens group, reference symbol f R represents the focal length of the rear lens group, reference symbol f 1 represents the focal length of the first lens component, reference symbol f 456 represents the total focal length of the fourth, fifth and sixth lens components, reference symbol f 8 represents the focal length of the eighth lens component, reference symbol a represents the distance from the final surface of the front lens group to the back focal point of the front lens group, reference symbol b represents the distance from the front surface of the rear lens group to the front focal point of the rear lens group, reference symbol r 6 represents the radius of curvature of the surface on the image side of the third lens component, reference symbol r 15 represent the radius of curvature of the surface on the image side of the seventh lens component, and reference symbol ν 1 represents Abbe's number of the first lens component.

Claim 3

A wide-angle zoom lens system according to claim 1, in which said second lens component is a negative lens and said wide-angle zoom lens system has the following numerical data: ______________________________________ r.sub.1 = 1.7377 d.sub.1 = 0.0486 n.sub.1 = 1.6968 ν.sub.1 = 64.15 r.sub.2 = 0.679 d.sub.2 = 0.3506 r.sub.3 = -2.7157 d.sub.3 = 0.0539 n.sub.2 = 1.757 ν.sub.2 = 55.52 r.sub.4 = 2.0895 d.sub.4 = 0.0053 r.sub.5 = 1.2351 d.sub.5 = 0.1775 n.sub.3 = 1.66998 ν.sub.3 = 47.87 r.sub.6 = -3.8272 d.sub.6 = l (variable) r.sub.7 = 2.2116 d.sub.7 = 0.0833 n.sub.4 = 1.618 ν.sub.4 = 39.32 r.sub.8 = -6.1865 d.sub.8 = 0.0042 r.sub.9 = 1.0978 d.sub.9 = 0.0833 n.sub.5 = 1.618 ν.sub.5 = 63.38 r.sub.10 = 6.0994 d.sub.10 = 0.0833 r.sub.11 = 0.7667 d.sub.11 = 0.2083 n.sub.6 = 1.618 ν.sub.6 = 63.38 r.sub.12 = -1.5956 d.sub.12 = 0.0417 n.sub.7 = 1.62588 ν.sub.7 = 35.7 r.sub.13 = 0.8222 d.sub.13 = 0.1111 r.sub.14 = -2.1127 d.sub.14 = 0.0417 n.sub.8 = 1.7495 ν.sub.8 = 35.19 r.sub.15 = 0.6815 d.sub.15 = 0.0722 r.sub.16 = 2.0557 d.sub.16 = 0.0833 n.sub.9 = 1.60342 ν.sub.9 = 38.01 r.sub.17 = -0.8465 f back focal length l 1 1.1939 1.29136 1.3744 1.4291 0.58547 1.8889 1.7523 0.07186 ______________________________________ wherein reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, and reference symbol f represents the focal length of the lens system as a whole.

Claim 4

A wide-angle zoom lens system according to claim 1, in which said second lens component is a negative lens and said wide-angle zoom lens system has the following numerical data: ______________________________________ r.sub.1 = 1.8793 d.sub.1 = 0.05 n.sub.1 = 1.6583 ν.sub.1 = 57.33 r.sub.2 = 0.6982 d.sub.2 = 0.3611 r.sub.3 = -5.1364 d.sub.3 = 0.0556 n.sub.2 = 1.7725 ν.sub.2 = 49.6 r.sub.4 = 1.7429 d.sub.4 = 0.0053 r.sub.5 = 1.1355 d.sub.5 = 0.1828 n.sub.3 = 1.66998 ν.sub.3 = 39.32 r.sub.6 = -8.5441 d.sub.6 = l (variable) r.sub.7 = 2.2816 d.sub.7 = 0.0833 n.sub.4 = 1.6516 ν.sub.4 = 58.67 r.sub.8 = -6.4978 d.sub.8 = 0.0042 r.sub.9 = 1.0444 d.sub.9 = 0.0833 n.sub.5 = 1.618 ν.sub.5 = 63.38 r.sub.10 = 5.5636 d.sub.10 = 0.0042 r.sub.11 = 0.7455 d.sub.11 = 0.2083 n.sub.6 = 1.58913 ν.sub.6 = 61.11 r.sub.12 = -1.5988 d.sub.12 = 0.0417 n.sub.7 = 1.5927 ν.sub.7 = 35.29 r.sub.13 = 0.7992 d.sub.13 = 0.1389 r.sub.14 = -2.2505 d.sub.14 = 0.0417 n.sub.8 = 1.7495 ν.sub.8 = 35.19 r.sub.15 = 0.6741 d.sub.15 = 0.0722 r.sub.16 = 2.805 d.sub.16 = 0.0833 n.sub.9 = 1.60342 ν.sub.9 = 38.01 r.sub.17 = -0.8461 f back focal length l 1 1.1916 1.38205 1.38389 1.42563 0.64136 1.92547 1.7558 0.0986 ______________________________________ wherein reference symbols r 1 , r 2 m . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, and reference symbol f represents the focal length of the lens system as a whole.

Claim 5

A wide-angle zoom lens system according to claim 1, in which said second lens component is a negative cemented doublet and said wide-angle zoom lens system has the following numerical data: ______________________________________ r.sub.1 = 1.7267 d.sub.1 = 0.0489 n.sub.1 = 1.6425 ν.sub.1 = 58.37 r.sub.2 = 0.6651 d.sub.2 = 0.3047 r.sub.3 = -2.4734 d.sub.3 =0.0508 n.sub.2 = 1.713 ν.sub.2 = 53.89 r.sub.3 ' = 1.2372 d'.sub.3 = 0.1111 n.sub.2 ' = 1.62041 ν.sub.2 ' = 60.27 r.sub.4 = 2.7631 d.sub.4 = 0.0056 r.sub.5 = 1.2479 d.sub.5 = 0.1667 n.sub.3 = 1.58144 ν.sub.3 = 40.75 r.sub.6 = -3.7532 d.sub.6 = l (variable) r.sub.7 = 2.1897 d.sub.7 = 0.0833 n.sub.4 = 1.618 ν.sub.4 = 63.38 r.sub.8 = -5.2499 d.sub.8 = 0.0042 r.sub.9 = 1.1168 d.sub.9 = 0.0833 n.sub.5 = 1.618 ν.sub.5 = 63.38 r.sub.10 = 6.7112 d.sub.10 = 0.0833 r.sub.11 = 0.7705 d.sub.11 = 0.2083 n.sub.6 = 1.618 ν.sub.6 = 63.38 r.sub.12 = -1.5946 d.sub.12 = 0.0417 n.sub.7 = 1.64769 ν.sub.7 = 33.8 r.sub.13 = 0.815 d.sub.13 = 0.1111 r.sub.14 = -2.0153 d.sub.14 = 0.0417 n.sub.8 = 1.7495 ν.sub.8 = 35.19 r.sub.15 = 0.7062 d.sub.15 = 0.0722 r.sub.16 = 2.3254 d.sub.16 = 0.0833 n.sub.9 = 1.61659 ν.sub.9 = 36.63 r.sub.17 = 0.8274 f back focal length l 1 1.1926 1.23364 1.3744 1.42775 0.52775 1.889 1.75094 0.01414 ______________________________________ wherein reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, and reference symbol f represents the focal length of the lens system as a whole.

Claim 6

A wide-angle zoom lens system according to claim 1, in which said second lens components consists of a negative lens and positive meniscus lens arranged with a very small airspace therebetween and said wide-angle zoom lens system has the following numerical data: ______________________________________ r.sub.1 = 1.6037 d.sub.1 = 0.0489 n.sub.1 = 1.64 ν.sub.1 = 60.09 r.sub.2 = 0.6846 d.sub.2 = 0.3047 r.sub.3 =-2.6055 d.sub.3 = 0.0508 n.sub.2 = 1.713 ν.sub.2 = 53.89 r.sub.3 ' = 1.23024 d.sub.3 ' = 0.0131 r.sub.3 " = 1.2397 d.sub.3 " = 0,1389 n.sub.2 ' = 1.56873 ν.sub.2 ' = 63.16 r.sub.4 = 2.7442 d.sub.4 = 0.0056 r.sub.5 = 1.3295 d.sub.5 = 0.1389 n.sub.3 = 1.57309 ν.sub.3 = 42.57 r.sub.6 =-4.0628 d.sub.6 = l (variable) r.sub.7 = 2.2115 d.sub.7 = 0.0833 n.sub.4 = 1.618 ν.sub.4 = 63.38 r.sub.8 = -5.2482 d.sub.8 = 0.0042 r.sub.9 = 1.1218 d.sub.9 = 0.0833 n.sub.5 = 1.618 ν.sub.5 = 63.38 r.sub.10 = 6.4679 d.sub.10 = 0.0833 r.sub.11 = 0.7671 d.sub.11 = 0.2083 n.sub.6 = 1.618 ν.sub.6 = 63.38 r.sub.12 =-1.5886 d.sub.12 = 0.0417 n.sub.7 = 1.62588 ν.sub.7 = 35.7 r.sub.13 = 0.8184 d.sub.13 = 0.1111 r.sub.14 =-1.9825 d.sub.14 = 0.0417 n.sub.8 = 1.7495 ν.sub.8 = 35.19 r.sub.15 = 0.6921 d.sub.15 = 0.0722 r.sub.16 = 2.3291 d.sub.16 = 0.0833 n.sub.9 = 1.60342 ν.sub.9 = 38.01 r.sub.17 =-0.8231 f back focal length l 1 1.1884 1.24264 1.3743 1.4235 0.53675 1.8889 1.7467 0.02314 ______________________________________ wherein reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, and reference symbol f represents the focal length of the lens system as a whole.