Compact zoom lens system with a high zooming ratio

Claim 2

A compact zoom lens system with a high zooming ratio comprising, in order from the object side, a first lens group having a positive refracting power, a second lens group having a positive refracting power and a third lens group having a negative refracting power, and being arranged to be zoomed by varying the space between said first lens group and said second lens group and the space between said second lens group and said third lens group, in which at least one graded refractive index lens having the distribution of the refractive index thereof in the direction of the optical axis is arranged in at least one lens group.

Claim 3

A compact zoom lens system with a high zooming ratio according to claim 1, in which said third lens group satisfies the following conditions (1) and (2): 0.4<|f.sub.3 /f.sub.W 51 <2 (1) 1<β.sub.3T /β.sub.3W <3 (2) wherein reference symbol f W represents the focal length of said zoom lens system as a whole in the wide-angle position, reference symbol f 3 represents the focal length of said third lens group, reference symbol β 3W represents the lateral magnification of said third lens group in the wide-angle position, reference symbol β 3T represents the lateral magnification of said third lens group in the telephoto position.

Claim 4

A compact zoom lens system with a high zooming ratio according to claim 1 or 2, in which said second lens group comprises a front lens group and a rear lens group, and the refracting powers of said front lens group and said rear lens group satisfy the following condition (3): 0.3<|f.sub.22 /f.sub.21 |<1.5 (3) wherein reference symbol f 21 represents the focal length of said front lens group of said second lens group and reference symbol f 22 represents the focal length of said rear lens group of said second lens group.

Claim 5

A compact zoom lens system with a high zooming ratio according to claim 3, in which said graded refractive index lens has the distribution of the refractive index expressed by the following formula: n(x)=n.sub.0 +n.sub.1 x+n.sub.2 x.sup.2 +n.sub.3 x.sup.3 + . . . wherein reference symbol x represents the distance in the optical direction from the origin which is set on the vertex of the object side surface of said graded refractive index lens, reference symbol n 0 represents the refractive index at the vertex of the object side surface of said graded refractive index lens and reference symbols n 1 , n 2 , n 3 , . . . respectively represent the 1st-, 2nd-, 3rd-, . . . order coefficients relating to x.

Claim 6

A compact zoom lens system with a high zooming ratio according to claim 4, in which said graded refractive index lens satisfies the following conditions (4) and (5): Δn.sub.A <0.15 (4) |n.sub.1 ·f.sub.W |<3.0 (5) wherein reference symbol Δn A represents the maximum difference of the refractive index on the optical axis from the object side surface of said graded refractive index lens to the image side surface thereof and reference symbol f W represents the focal length of said zoom lens system as a whole in the wide-angle position.

Claim 7

A compact zoom lens system with a high zooming ratio according to claim 5, in which said first lens group comprises a doublet cemented with a negative lens and a positive lens, and a positive lens, said second lens group comprises said front lens group involving at least a negative lens and a positive lens and said rear lens group having two positive lenses, a negative lens and a positive lens, and said third lens group comprises a positive meniscus lens and a negative lens.

Claim 8

A compact zoom lens system with a high zooming ratio according to claim 5, in which said first lens group comprises a negative lens, a positive lens and a positive lens, said second lens group comprises said front lens group involving at least a negative lens and a positive lens and said rear lens group having two positive lenses, a negative lens and a positive lens, and said third lens group comprises a positive meniscus lens and a negative lens.

Claim 9

A compact zoom lens system with a high zooming ratio according to claim 6, in which said compact zoom lens system with a high zooming ratio has the following numerical data: ______________________________________ f = 39.49-100.53, F/4.60-5.90 ______________________________________ r.sub.1 = 8331.050 d.sub.1 = 1.500 n.sub.01 = 1.80518 ν.sub.01 = 25.43 r.sub.2 = 19.240 d.sub.2 = 4.548 n.sub.02 Graded Refractive Index Lens r.sub.3 = 140.928 d.sub.3 = 0.049 r.sub.4 = 25.392 d.sub.4 = 3.894 n.sub.03 = 1.54072 ν.sub.03 = 47.20 r.sub.5 = -125.502 d.sub.5 = D1 (variable) r.sub.6 = -39.854 d.sub.6 = 1.235 n.sub.04 = 1.77250 ν.sub.04 = 49.66 r.sub.7 = 16.677 d.sub.7 = 1.867 r.sub.8 = 30.625 d.sub.8 = 3.000 n.sub.05 = 1.80518 ν.sub.05 = 25.43 r.sub.9 = -30.160 d.sub.9 = 1.102 r.sub.10 = -26.204 d.sub.10 = 1.193 n.sub.06 = 1.80440 ν.sub.06 = 39.58 r.sub.11 = -105.340 d.sub.11 = 5.900 r.sub.12 = ∞ (diaphragm) d.sub.12 = 2.123 r.sub.13 = 232.415 d.sub.13 = 3.500 n.sub.07 = 1.54771 ν.sub.07 = 62.83 r.sub.14 = -18.611 d.sub.14 = 0.060 r.sub.15 = 31.073 d.sub.15 = 4.391 n.sub.08 = 1.56965 ν.sub.08 = 49.33 r.sub.16 = -44.022 d.sub.16 = 0.750 r.sub.17 = -23.523 d.sub.17 = 2.599 n.sub.09 = 1.84666 ν.sub.09 = 23.88 r.sub.18 = 30.171 d.sub.18 = 2.860 r.sub.19 = 58.530 d.sub.19 = 3.200 n.sub.010 = 1.60342 ν.sub.010 = 38.01 r.sub.20 = -20.126 d.sub.20 = D2 (variable) r.sub.21 = -26.741 d.sub.21 = 2.800 n.sub.011 = 1.78472 ν.sub.011 = 25.68 r.sub.22 = -17.489 d.sub.22 = 1.902 r.sub.23 = -17.166 d.sub.23 = 1.750 n.sub.012 = 1.77250 ν.sub.012 =49.66 r.sub.24 = 117.152 ______________________________________ f 39.49 63.08 100.53 ______________________________________ D1 1.251 7.865 11.909 D2 17.796 10.257 4.679 ______________________________________ n(x) = n.sub.0 + n.sub.1 x + n.sub.2 x.sup.2 + n.sub.3 x.sup.3 n.sub.0 n.sub.1 ______________________________________ n(x) d 1.69957 -0.22036 × 10.sup.-3 g 1.72998 -0.23386 × 10.sup.-3 ______________________________________ n.sub.2 n.sub.3 ______________________________________ d -0.27717 × 10.sup.-4 0.10158 × 10.sup.-4 g -0.29993 × 10.sup.-4 0.10992 × 10.sup.-4 ______________________________________ |f.sub.3 /f.sub.W | = 0.727 β.sub.3.sbsb.T /β.sub.3.sbsb.W = 2.1460 |f.sub.22 /f.sub.21 | = 0.823 Δn.sub.A = 0.0006 |n.sub.1 · f.sub.W | = 0.0087 ______________________________________ 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 01 , n 02 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 01 , ν 02 , . . . respectively represent Abbe's numbers of respective lenses, and the coefficients of the refractive index distribution are for d- and g-rays.

Claim 10

A compact zoom lens system with a high zooming ratio according to claim 7, in which said compact zoom lens system with a high zooming ratio has the following numerical data: ______________________________________ f = 39.52-100.80, F/4.66-6.38 ______________________________________ r.sub.1 = 348.884 d.sub.1 = 1.500 n.sub.01 = 1.84666 ν.sub.01 = 23.88 r.sub.2 = 45.104 d.sub.2 = 0.880 r.sub.3 = 68.824 d.sub.3 = 3.479 n.sub.02 = 1.65100 ν.sub.02 = 56.15 r.sub.4 = 451.324 d.sub.4 = 0.200 r.sub.5 = 35.144 d.sub.5 = 4.500 n.sub.03 = 1.51602 ν.sub.03 = 56.80 r.sub.6 = -61.676 d.sub.6 = D1 (variable) r.sub.7 = -40.245 d.sub.7 = 1.300 n.sub.04 = 1.72916 ν.sub.04 = 54.68 r.sub.8 = 22.905 d.sub.8 = 0.800 r.sub.9 = 23.093 d.sub.9 = 2.506 n.sub.05 = 1.80518 ν.sub.05 = 25.43 r.sub.10 = 366.246 d.sub.10 = 1.900 r.sub.11 = -23.252 d.sub.11 = 1.300 n.sub.06 = 1.77250 ν.sub.06 = 49.66 r.sub.12 = -30.419 d.sub.12 = 8.863 r.sub.13 = ∞ (diaphragm) d.sub.13 = 1.913 r.sub.14 = -85.767 d.sub.14 = 2.800 n.sub.07 = 1.61293 ν.sub.07 = 37.00 r.sub.15 = -26.666 d.sub.15 = 0.100 r.sub.16 = 28.014 d.sub.16 = 3.285 n.sub.08 = 1.58913 ν.sub.08 = 60.97 r.sub.17 = -33.501 d.sub.17 = 1.159 r.sub.18 = -20.032 d.sub.18 = 1.618 n.sub.09 Graded Refractive Index Lens r.sub.19 = 36.370 d.sub.19 = 2.362 r.sub.20 = 62.364 d.sub.20 = 3.286 n.sub.010 = 1.56873 ν.sub.010 = 63.16 r.sub.21 = -20.778 d.sub.21 = D2 (variable) r.sub.22 = -33.699 d.sub.22 = 3.297 n.sub.011 = 1.78472 ν.sub.011 = 25.68 r.sub.23 = -18.888 d.sub.23 = 2.207 r.sub.24 = -17.065 d.sub.24 = 1.601 n.sub.012 = 1.78590 ν.sub.012 = 44.18 r.sub.25 = 102.469 ______________________________________ f 39.52 63.11 100.80 ______________________________________ D1 2.037 5.521 9.611 D2 16.310 8.204 2.500 ______________________________________ n(x) = n.sub.0 + n.sub.1 x n.sub.0 n.sub.1 ______________________________________ n(x) d 1.70545 -0.5 × 10.sup.-2 g 1.73626 -0.533 × 10.sup.-2 ______________________________________ |f.sub.3 /f.sub.W | = 0.749 β.sub.3.sbsb.T /β.sub.3.sbsb.W = 2.2699 |f.sub.22 /f.sub.21 | = 0.650 Δn.sub.A = 0.0081 |n.sub.1 · f.sub.W | = 0.1976 ______________________________________ 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 01 , n 02 , . . . respectively represent refractive indices of respective lenses reference symbols ν 01 , ν 02 , . . . respectively represent Abbe's numbers of respective lenses, and the coefficients of the refractive index distribution are for d- and g-rays.

Claim 11

A compact zoom lens system with a high zooming ratio according to claim 7, in which said compact zoom lens system with a high zooming ratio has the following numerical data: ______________________________________ f = 39.58-100.54, F/4.66-6.38 ______________________________________ r.sub.1 = 348.884 d.sub.1 = 1.500 n.sub.01 = 1.83400 ν.sub.01 =37.16 r.sub.2 = 35.222 d.sub.2 = 1.100 r.sub.3 = 73.527 d.sub.3 = 3.479 n.sub.02 = 1.65844 ν.sub.02 = 50.86 r.sub.4 = 4200.209 d.sub.4 = 0.200 r.sub.5 = 26.196 d.sub.5 = 5.200 n.sub.03 = 1.51821 ν.sub.03 = 65.04 r.sub.6 = -75.680 d.sub.6 = D1 (variable) r.sub.7 = -32.768 d.sub.7 = 1.300 n.sub.04 = 1.78590 ν.sub.04 = 44.18 r.sub.8 = 18.248 d.sub.8 = 0.800 r.sub.9 = 21.741 d.sub.9 = 2.506 n.sub.05 = 1.80518 ν.sub.05 = 25.43 r.sub.10 = -908.077 d.sub.10 = 9.823 r.sub.11 = ∞ (diaphragm) d.sub.11 = 1.913 r.sub.12 = -132.304 d.sub.12 = 2.800 n.sub.06 = 1.61484 ν.sub.06 = 51.17 r.sub.13 = -26.305 d.sub.13 = 0.100 r.sub.14 = 28.521 d.sub.14 = 4.000 n.sub.07 = 1.58913 ν.sub.07 = 60.97 r.sub.15 = -27.839 d.sub.15 = 1.159 r.sub.16 = -20.897 d.sub.16 = 1.618 n.sub.08 Graded Refractive Index Lens r.sub.17 = 39.246 d.sub.17 = 2.362 r.sub.18 = 178.074 d.sub.18 = 3.286 n.sub.09 = 1.57135 ν.sub.09 = 52.92 r.sub.19 = -21.364 d.sub.19 = D2 (variable) r.sub.20 = -35.509 d.sub.20 = 3.297 n.sub.010 = 1.78472 ν.sub.010 = 25.68 r.sub.21 = -18.181 d.sub.21 = 1.507 r.sub.22 = -17.065 d.sub.22 = 1.601 n.sub.011 = 1.78650 ν.sub.011 = 50.00 r.sub.23 = 124.801 ______________________________________ f 39.58 63.11 100.54 ______________________________________ D1 2.500 6.889 11.083 D2 18.382 9.092 2.500 ______________________________________ n(x) = n.sub.0 + n.sub.1 x n.sub.0 n.sub.1 ______________________________________ n(x) d 1.74077 -0.5 × 10.sup.-2 g 1.77589 -0.533 × 10.sup.-2 ______________________________________ |f.sub.3 /f.sub.W | = 0.841 β.sub.3.sbsb.T /β.sub.3.sbsb.W = 2.2376 |f.sub.22 /f.sub.21 | = 0.745 Δn.sub.A = 0.0081 |n.sub.1 · f.sub.W | = 0.1979 ______________________________________ 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 01 , n 02 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 01 , ν 02 , . . . respectively represent Abbe's numbers of respective lenses, and the coefficients of the refractive index distribution are for d- and g-rays.