Zoom lens including a wide angle of view

Claim 2

A zoom lens including a wide angle of view and consisting of, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small.

Claim 3

A zoom lens according to claim 1, which satisfies the following condition: 0.5<V.sub.2 /V<0.9 where V is the zoom ratio by the entire lens system and V 2 is the ratio of the magnification at the wide angle end by said second lens group alone to the magnification at the telephoto end.

Claim 4

A zoom lens according to claim 1 which further comprises cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means.

Claim 5

A zoom lens according to claim 3, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group has substantially the same positions at the wide angle end and the telephoto end relative to the image plane and is smoothly moved so as to lie most adjacent to the object side at the intermediate position, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection.

Claim 6

A zoom lens according to claim 3, wherein when magnification change is effected from the wide angle end to the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group is monotonously moved toward the object side while depicting a non-linear locus and lies more adjacent to the object side at the telephoto end than at the wide angle end, and said third lens group is rectilinearly moved toward the object side at the same velocity as said first lens group.

Claim 7

A zoom lens according to claim 3, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group is monotonously moved toward the object side while depicting a non-linear locus and lies more adjacent to the object side at the telephoto end than at the wide angle end, said third lens group has a forward group of positive refractive power and a rearward group of positive refractive power, and said forward group and said rearward group are rectilinearly moved toward the object side at different velocities.

Claim 8

A zoom lens according to claim 6, wherein the movement velocity of said forward group in said third lens group is less than that of said rearward group and the ratio of the two velocities is in the range of 0.5:1.0-0.9:1.0.

Claim 9

A zoom lens according to claim 7, wherein said forward group in said third lens group has, in succession from the object side, a biconvex positive lens (L 9 ) having its surface of sharper curvature facing the image side, a negative meniscus lens (L 10 ) having its convex surface facing the image side, and a positive meniscus lens (L 11 ) having its convex surface facing the object side.

Claim 10

A zoom lens according to claim 8, wherein when the shape factors of the successive lenses of said forward group in said third lens group are q 10 , q 11 and g 12 , the following conditions are satisified: 0.3<|q.sub.9 <1.0 2.0<q.sub.10 <5.0 3.0<q.sub.11 <8.0 where the shaper factor q is defined as ##EQU8## where R 1 is the radius of curvature of the surface of each lens which is adjacent to the object side and R 2 is the radius of curvature of the surface of each lens which is adjacent to the image side.

Claim 11

A zoom lens according to claim 9, wherein said rearward group in said third lens group has, in succession from the object side, a biconvex positive lens (L 12 ), a biconcave lens (L 13 ), a positive lens (L 14 ) having its surface of shaper curvature facing the image side, a positive lens (L 15 ), and a negative meniscus lens (L 16 ) having its convex surface facing the image side.

Claim 12

A zoom lens according to claim 10, wherein numerical data are as follows: __________________________________________________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.5, Image height y = 21.6 Radius of Center thickness Refractive curvature and air space index Abbe number __________________________________________________________________________ r.sub.1 163.84 d.sub.1 1.3 n.sub.1 1.805 ν.sub.1 25.3 L.sub.1 r.sub.2 60.38 d.sub.2 0.6 r.sub.3 69.92 d.sub.3 6.2 n.sub.2 1.603 ν.sub.2 60.6 L.sub.2 G.sub.1 r.sub.4 -124.35 d.sub.4 0.1 r.sub.5 32.82 d.sub.5 3.9 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.6 67.73 d.sub.6 variable r.sub.7 58.60 d.sub.7 1.0 n.sub.4 1.796 ν.sub.4 45.5 L.sub.4 r.sub.8 17.03 d.sub.8 3.0 r.sub.9 -207.96 d.sub.9 3.5 n.sub.5 1.805 ν.sub.5 25.3 L.sub.5 r.sub.10 - 20.31 d.sub.10 1.0 n.sub.6 1.796 ν.sub.6 45.5 L.sub.6 G.sub.2 r.sub.11 -187.13 d.sub.11 2.7 r.sub.12 -21.24 d.sub.12 1.0 n.sub.7 1.713 ν.sub.7 53.9 L.sub.7 r.sub.13 17.22 d.sub.13 3.3 n.sub.8 1.796 ν.sub.8 40.9 L.sub.8 r.sub.14 -1098.84 d.sub.14 variable r.sub.15 76.43 d.sub.15 4.0 n.sub.9 1.713 ν.sub.9 53.9 L.sub.9 r.sub.16 -25.73 d.sub.16 0.5 r.sub.17 -21.84 d.sub.17 1.0 n.sub.10 1.805 ν.sub.10 25.3 L.sub.10 G.sub.31 r.sub.18 -39.02 d.sub.18 0.1 r.sub.19 34.55 d.sub.19 2.0 n.sub.11 1.568 ν.sub.11 56.0 L.sub.11 r.sub.20 53.69 d.sub.20 variable r.sub.21 29.35 d.sub.21 4.5 n.sub.12 1.563 ν.sub.12 60.8 L.sub.12 G.sub.3 r.sub.22 -45.83 d.sub.22 1.9 r.sub.23 -41.49 d.sub.23 1.5 n.sub.13 1.796 ν.sub.13 45.5 L.sub.13 r.sub.24 29.65 d.sub.24 2.0 r.sub.25 994.65 d.sub. 25 2.5 n.sub.14 1.516 ν.sub.14 64.1 L.sub.14 G.sub.32 r.sub.26 -38.85 d.sub.26 0.1 r.sub.27 857.81 d.sub.27 5.0 n.sub.15 1.516 ν.sub.15 64.1 L.sub.15 r.sub.28 -25.42 d.sub.28 0.6 r.sub.29 -21.42 d.sub.29 1.4 n.sub.16 1.749 ν.sub.16 35.1 L.sub.16 r.sub.30 -29.0 __________________________________________________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 103 __________________________________________________________________________ d.sub.6 1.28 10.99 20.32 d.sub.14 13.0 7.17 1.72 d.sub.20 9.66 5.79 1.91 Step, ahead of L.sub.9 0.8 0.8 0.8 Bf 52.04 64.97 77.87 v.sub.2 = 1.817 __________________________________________________________________________

Claim 13

A zoom lens according to claim 10, wherein numerical data are as follows: __________________________________________________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.5, Image height y = 21.6 Radius of Center thickness Refractive curvature and air space index Abbe number __________________________________________________________________________ r.sub.1 146.56 d.sub.1 1.3 n.sub.1 1.805 ν.sub.1 25.3 L.sub.1 r.sub.2 58.02 d.sub.2 0.8 r.sub.3 63.36 d.sub.3 6.2 n.sub.2 1.603 ν.sub.2 60.6 L.sub.2 G.sub.1 r.sub.4 -138.23 d.sub.4 0.1 r.sub.5 33.60 d.sub.5 3.9 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.6 67.70 d.sub.6 variable r.sub.7 62.53 d.sub.7 1.0 n.sub.4 1.796 ν.sub.4 45.5 L.sub.4 r.sub.8 17.12 d.sub.8 3.0 r.sub.9 -208.23 d.sub.9 3.5 n.sub.5 1.805 ν.sub.5 25.3 L.sub.5 r.sub.10 -20.51 d.sub.10 1.0 n.sub.6 1.796 ν.sub.6 45.5 L.sub.6 G.sub.2 r.sub.11 -177.01 d.sub.11 2.7 r.sub.12 -21.42 d.sub.12 1.0 n.sub.7 1.713 ν.sub.7 53.9 L.sub.7 r.sub.13 17.19 d.sub.13 3.3 n.sub.8 1.796 ν.sub.8 40.9 L.sub.8 r.sub.14 -975.69 d.sub.14 variable r.sub.15 87.95 d.sub.15 4.0 n.sub.9 1.713 ν.sub.9 53.9 L.sub.9 r.sub.16 -23.88 d.sub.16 1.11 r.sub.17 -20.25 d.sub.17 1.0 n.sub.10 1.805 ν.sub.10 25.3 L.sub.10 G.sub.31 r.sub.18 -35.29 d.sub.18 1.04 r.sub.19 28.82 d.sub.19 2.0 n.sub.11 1.568 ν.sub.11 56.0 L.sub.11 r.sub.20 39.06 d.sub.20 variable r.sub.21 25.36 d.sub.21 4.0 n.sub.12 1.563 ν.sub.12 60.8 L.sub.12 G.sub.3 r.sub.22 -62.61 d.sub.22 1.87 r.sub.23 -52.01 d.sub.23 1.0 n.sub.13 1.796 ν.sub.13 45.5 L.sub.13 r.sub.24 26.06 d.sub.24 2.73 G.sub.32 r.sub.25 -77.80 d.sub.25 2.0 n.sub.14 1.518 ν.sub.14 60.3 L.sub.14 r.sub.26 -26.94 d.sub.26 0.1 r.sub.27 86.70 d.sub.27 4.5 n.sub.15 1.563 ν.sub.15 60.8 L.sub.15 r.sub.28 -25.30 d.sub.28 1.0 n.sub.16 1.796 ν.sub.16 40.9 L.sub.16 r.sub.29 -51.69 __________________________________________________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 103 __________________________________________________________________________ d.sub.6 1.20 10.91 20.23 d.sub.14 13.06 7.22 1.77 d.sub.20 9.18 5.30 1.43 Stop, ahead of L.sub.9 0.8 0.8 0.8 Bf 52.77 65.70 78.60 v.sub.2 = 1.817 __________________________________________________________________________

Claim 14

A zoom lens according to claim 9, wherein said rearward group in said third lens group has, in succession from the object side, a positive meniscus lens (L 12 ) having its convex surface facing the object side, a negative miniscus lens (L 13 ) cemented thereto and having its convex surface facing the object side, a positive lens (L 14 ) having its surface of sharper curvature facing the image side, a positive lens (L 15 ) having its surface of sharper curvature facing the image side, and a negative meniscus lens L 16 cemented thereto or separated therefrom and having its convex surface facing the image side.

Claim 15

A zoom lens according to claim 13, which satisfies the following conditions: 0.2<r.sub.a /f.sub.32 <0.4 0.2<r.sub.b /f.sub.32 <0.4 where f 32 is the focal length of said rearward group in said third lens group, r a is the radius of curvature of the surface of said positive meniscus lens (L 12 ) which is adjacent to the object side, and r b is the radius of curvature of the surface of said negative meniscus lens (L 13 ) which is adjacent to the image side, said positive meniscus lens (L 12 ) and said negative meniscus lens (L 13 ) being cemented together.

Claim 16

A zoom lens according to claim 14, wherein numerical data are as follows: __________________________________________________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.5, Image height y = 21.6 Radius of Center thickness Refractive curvature and air space index Abbe number __________________________________________________________________________ r.sub.1 157.33 d.sub.1 1.3 n.sub.1 1.805 ν.sub.1 25.3 L.sub.1 r.sub.2 59.72 d.sub.2 0.6 r.sub.3 67.46 d.sub.3 6.2 n.sub.2 1.603 ν.sub.2 60.6 L.sub.2 G.sub.1 r.sub.4 -130.89 d.sub.4 0.1 r.sub.5 33.37 d.sub.5 3.9 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.6 69.37 d.sub.6 variable r.sub.7 63.56 d.sub.7 1.0 n.sub.4 1.796 ν.sub.4 45.5 L.sub.4 r.sub.8 17.11 d.sub.8 3.0 r.sub.9 -204.46 d.sub.9 3.5 n.sub.5 1.805 ν.sub.5 25.3 L.sub.5 r.sub. 10 -20.33 d.sub.10 1.0 n.sub.6 1.796 ν.sub.6 45.5 L.sub.6 G.sub.2 r.sub.11 -192.0 d.sub.11 2.7 r.sub.12 -21.45 d.sub.12 1.0 n.sub.7 1.713 ν.sub.7 53.9 L.sub.7 r.sub.13 17.47 d.sub.13 3.3 n.sub.8 1.796 ν.sub.8 40.9 L.sub.8 r.sub.14 -568.20 d.sub.14 variable r.sub.15 88.81 d.sub.15 4.0 n.sub.9 1.713 ν.sub.9 53.9 L.sub.9 r.sub.16 -25.60 d.sub.16 0.5 r.sub.17 -21.70 d.sub.17 1.0 n.sub.10 1.805 ν.sub.10 25.3 L.sub.10 G.sub.31 r.sub.18 -38.63 d.sub.18 0.1 r.sub.19 35.59 d.sub.19 2.0 n.sub.11 1.568 ν.sub.11 56.0 L.sub.11 r.sub.20 64.42 d.sub.20 variable r.sub.21 23.62 d.sub.21 5.0 n.sub.12 1.563 ν.sub.12 60.8 L.sub.12 G.sub.3 r.sub.22 94.99 d.sub.22 1.5 n.sub.13 1.796 ν.sub.13 45.5 L.sub.13 r.sub.23 22.35 d.sub.23 2.0 r.sub.24 91.31 d.sub.24 3.0 n.sub.14 1.516 ν.sub.14 64.1 L.sub.14 G.sub.32 r.sub.25 -36.06 d.sub.25 0.1 r.sub.26 -132.82 d.sub.26 5.0 n.sub.15 1.518 ν.sub.15 60.3 L.sub.15 r.sub.27 -24.13 d.sub.27 0.6 r.sub.28 -21.25 d.sub.28 1.4 n.sub.16 1.749 ν.sub.16 35.1 L.sub.16 r.sub.29 -39.27 __________________________________________________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 103 __________________________________________________________________________ d.sub.6 1.51 11.04 20.26 d.sub.14 12.49 6.75 1.38 d.sub.20 10.11 6.3 2.46 Stop, ahead of L.sub.9 0.8 0.8 0.8 Bf 51.01 63.68 76.50 v.sub.2 = 1.817 __________________________________________________________________________

Claim 17

A zoom lens according to claim 14, wherein numerical data are as follows: __________________________________________________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.5, Image height y = 21.6 Radius of Center thickness Refractive curvature and air space index Abbe number __________________________________________________________________________ r.sub.1 150.69 d.sub.1 1.3 n.sub.1 1.805 ν.sub.1 25.3 L.sub.1 r.sub.2 58.13 d.sub.2 0.4 r.sub.3 66.23 d.sub.3 6.2 n.sub.2 1.603 ν.sub.2 60.6 L.sub.2 G.sub.1 r.sub.4 -128.09 d.sub.4 0.1 r.sub.5 33.14 d.sub.5 3.9 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.6 67.54 d.sub.6 variable r.sub.7 62.79 d.sub.7 1.0 n.sub.4 1.796 ν.sub.4 45.5 L.sub.4 r.sub.8 17.07 d.sub.8 3.0 r.sub.9 -213.87 d.sub.9 1.0 n.sub.5 1.805 ν.sub.5 25.3 L.sub.5 r.sub.10 -20.49 d.sub.10 1.0 n.sub.6 1.796 ν.sub.6 45.5 L.sub.6 G.sub.2 r.sub.11 -194.15 d.sub.11 2.7 r.sub.12 -21.48 d.sub.12 1.0 n.sub.7 1.713 ν.sub.7 53.9 L.sub.7 r.sub.13 17.23 d.sub.13 3.5 n.sub.8 1.796 ν.sub.8 40.9 L.sub.8 r.sub.14 -696058 d.sub.14 variable r.sub.15 122.05 d.sub.15 4.0 n.sub.9 1.713 ν.sub.9 53.9 L.sub.8 r.sub.16 -24.80 d.sub.16 0.4 r.sub.17 -21.54 d.sub.17 1.0 n.sub.10 1.805 ν.sub.10 25.3 L.sub.10 G.sub.31 r.sub.18 -38.91 d.sub.18 0.1 r.sub.19 35.07 d.sub.19 2.0 n.sub.11 1.568 ν.sub.11 56.0 L.sub.11 r.sub.20 72.08 d.sub.20 variable r.sub.21 21.96 d.sub.21 4.0 n.sub.12 1.563 ν.sub.12 60.8 L.sub.12 G.sub.3 r.sub.22 34.58 d.sub.22 1.5 n.sub.13 1.796 ν.sub.13 45.5 L.sub.13 r.sub.23 20.50 d.sub.23 2.0 r.sub.24 104.25 d.sub.24 4.0 n.sub.14 1.518 ν.sub.14 60.3 L.sub.14 G.sub.32 r.sub.25 -31.38 d.sub.25 0.1 r.sub.26 -95.95 d.sub.26 5.5 n.sub.15 1.563 ν.sub.15 60.8 L.sub.15 r.sub.27 -16.37 d.sub.27 1.4 n.sub.16 1.796 ν.sub.16 40.9 L.sub.16 r.sub.28 -45.88 __________________________________________________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 103 __________________________________________________________________________ d.sub.6 0.98 10.62 19.77 d.sub.14 12.52 6.77 1.49 d.sub.20 10.84 6.96 3.08 Stop, ahead of L.sub.9 0.8 0.8 0.8 Bf 52.36 65.30 78.24 v.sub.2 = 1.817 __________________________________________________________________________

Claim 18

A zoom lens including a wide angle of view and consisting of, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, and wherein, when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group depicts a curve convex toward the object side and lies most adjacent to the object side at a position between the wide angle end and the telephoto end, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection.

Claim 19

A zoom lens including a wide angle of view and consisting of, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, and wherein, when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group depicts a curve convex toward the object side and lies most adjacent to the object side at a position between the wide angle end and the telephoto end, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection.

Claim 20

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group depicts a curve convex toward the object side and lies most adjacent to the object side at a position between the wide angle end and the telephoto end, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.

Claim 21

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group depicts a curve convex toward the object side and lies most adjacent to the object side at a position between the wide angle end and the telephoto end, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.

Claim 22

A zoom lens according to claim 18, wherein said third lens group (G 3 ) has, in succession from the object side, a positive lens (L 9 ) having its surface of sharper curvature facing the image side, a negative meniscus lens (L 10 ) cemented thereto and having its convex surface facing the image side, a positive lens (L 11 ) having its surface of sharper curvature facing the object side, a negative lens (L 12 ) having its surface of sharper curvature facing the image side, a positive lens (L 13 ) having its surface of sharper curvature facing the image side, a positive lens (L 14 ) having its surface of sharper curvature facing the image side, and a negative lens (L 15 ) cemented thereto and having its surface of sharper curvature facing the object side.

Claim 23

A zoom lens according to claim 19, wherein, when the shape factors of the positive lens (L 11 ) in said third lens group (G 3 ) having its surface of sharper curvature facing the object side and the negative lens (L 12 ) having its surface of sharper curvature facing the image side are q 11 and q 12 , respectively, the following conditions are satisfied: 0.8<q.sub.11 <1.2 0.7<|q.sub.12 |<2.0 where the shape factor q is defined as ##EQU9## where R 1 is the radius of curvature of the surface of each lens which is adjacent to the object side and R 2 is the radius of curvature of the surface of each lens which is adjacent to the image side.

Claim 24

A zoom lens according to the claim 20, wherein numerical data are as follows: __________________________________________________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5, Image height y = 21.6 Radius of Center thickness curvature and air space Refractive index Abbe number __________________________________________________________________________ r.sub.1 130.39 d.sub.1 1.3 n.sub.1 1.784 ν.sub.1 26.0 L.sub.1 r.sub.2 51.24 d.sub.2 7.7 n.sub.2 1.563 ν.sub.2 60.8 L.sub.2 r.sub.3 -135.31 d.sub.3 0.1 G.sub.1 r.sub.4 34.94 d.sub.4 4.5 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.5 79.56 d.sub.5 variable r.sub.6 51.99 d.sub.6 1.0 n.sub.4 1.772 ν.sub.4 49.4 L.sub.4 r.sub.7 16.04 d.sub.7 4.0 r.sub.8 -31.09 d.sub.8 2.0 n.sub.5 1.756 ν.sub.5 31.7 L.sub.5 r.sub.9 -25.98 d.sub.9 0.8 r.sub.10 -43.98 d.sub.10 1.3 n.sub.6 1.713 ν.sub.6 53.9 L.sub.6 r.sub.11 -251.47 d.sub.11 3.0 r.sub.12 -16.14 d.sub.12 1.0 n.sub.7 1.620 ν.sub.7 60.2 L.sub.7 r.sub.13 32.55 d.sub.13 4.5 n.sub.8 1.756 ν.sub.8 31.7 L.sub.8 r.sub.14 -42.44 d.sub.14 variable r.sub.15 58.50 d.sub.15 6.5 n.sub.9 1.501 ν.sub.9 56.4 L.sub.9 r.sub.16 -21.24 d.sub.16 1.2 n.sub.10 1.796 ν.sub.10 45.5 L.sub.10 r.sub.17 -57.27 d.sub.17 0.1 r.sub.18 28.31 d.sub.18 5.0 n.sub.11 1.514 ν.sub.11 54.6 L.sub.11 r.sub.19 -1023.03 d.sub.19 6.3 r.sub.20 128.42 d.sub.20 1.5 n.sub.12 1.755 ν.sub.12 27.6 L.sub.12 G.sub.3 r.sub.21 32.68 d.sub.21 3.4 r.sub.22 -157.59 d.sub.22 3.4 n.sub.13 1.518 ν.sub.13 60.3 L.sub.13 r.sub.23 -33.35 d.sub.23 0.2 r.sub.24 36.88 d.sub.24 11.0 n.sub.14 1.516 ν.sub.14 64.1 L.sub.14 r.sub.25 - 19.33 d.sub.25 1.0 n.sub.15 1.796 ν.sub.15 45.5 L.sub.15 r.sub.26 -95.09 __________________________________________________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 103 __________________________________________________________________________ d.sub.5 1.12 10.22 21.60 d.sub.14 17.94 9.80 2.37 Stop, behind L.sub.8 14.6 3.2 1.6 Bf 57.67 69.12 70.72 v.sub.2 = 2.204 __________________________________________________________________________

Claim 25

A zoom lens according to claim 20, wherein numerical data are as follows: ______________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.3, Image height y = 21.6 Center Refrac- Radius of thickness tive Abbe curvature air space index number ______________________________________ r.sub.1 178.48 d.sub.1 1.3 n.sub.1 1.755 ν.sub.1 27.6 L.sub.1 r.sub.2 46.12 d.sub.2 8.5 n.sub.2 1.547 ν.sub.2 53.6 L.sub.2 r.sub.3 -101.71 d.sub.3 0.1 G.sub.1 r.sub.4 32.61 d.sub.4 4.0 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.5 73.64 d.sub.5 vari- able r.sub.6 62.48 d.sub.6 1.0 n.sub.4 1.796 ν.sub.4 40.9 L.sub.4 r.sub.7 15.51 d.sub.7 4.1 r.sub.8 -172.67 d.sub.8 2.7 n.sub.5 1.795 ν.sub.5 28.5 L.sub.5 r.sub.9 -25.48 d.sub.9 1.3 n.sub.6 1.796 ν.sub.6 40.9 L.sub.6 G.sub.2 r.sub.10 272.88 d.sub.10 2.2 r.sub.11 -16.25 d.sub.11 1.0 n.sub.7 1.582 ν.sub.7 46.4 L.sub.7 r.sub.12 32.07 d.sub.12 3.7 n.sub.8 1.795 ν.sub.8 28.5 L.sub.8 r.sub.13 -40.23 d.sub.13 vari- able r.sub.14 62.70 d.sub.14 5.5 n.sub.9 1.501 ν.sub.9 56.4 L.sub.9 r.sub.15 -20.68 d.sub.15 1.2 n.sub.10 1.796 ν.sub.10 45.5 L.sub.10 r.sub.16 -55.81 d.sub.16 0.1 r.sub.17 25.11 d.sub.17 4.3 n.sub.11 1.514 ν.sub.11 54.6 L.sub.11 r.sub.18 1029.84 d.sub.18 6.2 r.sub.19 -611.14 d.sub.19 3.0 n.sub.12 1.795 ν.sub.12 28.5 L.sub.12 G.sub.3 r.sub.20 38.31 d.sub.20 2.5 r.sub.21 -247.30 d.sub.21 3.3 n.sub.13 1.620 ν.sub.13 60.2 L.sub.13 r.sub.22 -27.81 d.sub.22 0.1 r.sub.23 32.10 d.sub.23 8.2 n.sub.14 1.501 ν.sub. 14 56.4 L.sub.14 r.sub.24 -17.98 d.sub.24 1.0 n.sub.15 1.796 ν.sub.15 45.5 L.sub.15 r.sub.25 -373.38 ______________________________________ F.sub.W = 36 F.sub.M = 60 F.sub.T = 102.5 ______________________________________ d.sub.5 0.97 9.90 20.42 d.sub.13 20.57 11.73 3.44 Stop, behind L.sub.8 9.6 7.4 2.3 Bf 57.57 62.27 74.70 v.sub.2 = 2.024 ______________________________________

Claim 26

A zoom lens according to claim 20, wherein numerical data are as follows: ______________________________________ Focal length F = 35˜105, Zoom ratio 3, F-number 3.5˜4.3, Image height y = 21.6 Center thickness Refrac- Radius of and air tive Abbe curvature space index number ______________________________________ r.sub.1 130.66 d.sub.1 1.3 n.sub.1 1.795 ν.sub.1 28.5 L.sub.1 r.sub.2 46.67 d.sub.2 1.0 r.sub.3 46.51 d.sub.3 8.5 n.sub.2 1.563 ν.sub.2 60.8 L.sub.2 G.sub.1 r.sub.4 -112.14 d.sub.4 0.1 r.sub.5 31.47 d.sub.5 4.0 n.sub.3 1.603 ν.sub.3 60.6 L.sub.3 r.sub.6 58.68 d.sub.6 vari- able r.sub.7 62.48 d.sub.7 1.0 n.sub.4 1.796 ν.sub.4 40.9 L.sub.4 r.sub.8 15.51 d.sub.8 4.1 r.sub.9 -172.67 d.sub.9 2.75 n.sub.5 1.795 ν.sub.5 28.5 L.sub.5 r.sub.10 -25.48 d.sub.10 1.3 n.sub.6 1.796 ν.sub.6 40.9 L.sub.6 G.sub.2 r.sub.11 272.88 d.sub.11 2.29 r.sub.12 -16.25 d.sub.12 1.0 n.sub.7 1.582 ν.sub.7 46.4 L.sub.7 r.sub.13 32.07 d.sub.13 3.7 n.sub.8 1.795 ν.sub.8 28.5 L.sub.8 r.sub.14 -40.23 d.sub.14 vari- able r.sub.15 62.99 d.sub.15 5.5 n.sub.9 1.501 ν.sub.9 56.4 L.sub.9 r.sub.16 -20.77 d.sub.16 1.2 n.sub.10 1.796 ν.sub.10 45.5 L.sub.10 r.sub.17 -56.06 d.sub.17 0.1 r.sub.18 25.23 d.sub.18 4.3 n.sub.11 1.514 ν.sub.11 54.6 L.sub.11 r.sub.19 1034.62 d.sub.19 6.9 r.sub.20 -856.49 d.sub.20 1.5 n.sub.12 1.795 ν.sub.12 28.5 L.sub.12 G.sub.3 r.sub.21 38.01 d.sub.21 2.59 r.sub.22 -851.48 d.sub.22 4.0 n.sub.13 1.620 ν.sub.13 60.2 L.sub.13 r.sub.23 -29.36 d.sub.23 0.16 r.sub.24 32.76 d.sub.24 8.2 n.sub. 14 1.501 ν.sub.14 56.4 L.sub.14 r.sub.25 -18.36 d.sub.25 1.0 n.sub.15 1.796 ν.sub.15 45.5 L.sub.15 r.sub.26 -678.32 ______________________________________ F.sub.W = 36.2 F.sub.M = 60 F.sub.T = 102.5 ______________________________________ d.sub.6 1.04 9.96 18.64 d.sub.14 21.05 12.13 3.45 Stop, behind L.sub.8 10.0 6.1 2.1 Bf 57.37 68.90 79.79 v.sub.2 = 1.857 ______________________________________

Claim 27

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group has substantially the same positions at the wide angle end and the telephoto end relative to the image plane and is smoothly moved so as to lie most adjacent to the object side at the intermediate position, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.

Claim 28

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magnification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, said zoom lens comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end toward the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group has substantially the same positions at the wide angle end and the telephoto end relative to the image plane and is smoothly moved so as to lie most adjacent to the object side at the intermediate position, and said third lens group has the image plane correcting function and is monotonously moved toward the object side while depicting a non-linear locus having a point of inflection, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.

Claim 29

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end to the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group is monotonously moved toward the object side while depicting a non-linear locus and lies more adjacent to the object side at the telephoto end than at the wide angle end, and said third lens group is rectilinearly moved toward the object side at the same velocity as said first lens group, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.

Claim 30

A zoom lens including a wide angle of view and having, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power and capable of effecting magification change by the second lens group being moved relative to the first and third lens groups, characterized in that when zooming is effected from the wide angle end to the telephoto end, said first lens group and said third lens group are monotonously moved toward the object side and said second lens group is moved toward the object side at least near the wide angle end so that the position at which the principal light ray of a maximum angle of view cuts said first lens group is nearer to the optical axis, whereby the aperture of said first lens group can be kept small, further comprising cam means rotatable to effect magnification change, said first, second and third lens groups being moved in accordance with the angle of the rotation of said cam means, wherein when magnification change is effected from the wide angle end to the telephoto end by the rotation of said cam means, said first lens group is rectilinearly moved toward the object side, said second lens group is monotonously moved toward the object side while depicting a non-linear locus and lies more adjacent to the object side at the telephoto end than at the wide angle end, and said third lens group is rectilinearly moved toward the object side at the same velocity as said first lens group, and wherein said first lens group has, in succession from the object side, a negative meniscus lens (L 1 ) having its convex surface facing the object side, a biconvex positive lens (L 2 ) cemented thereto or separated therefrom, and a positive meniscus lens (L 3 ) having its convex surface facing the object side, and said second lens group has, in succession from the object side, a negative meniscus lens (L 4 ) having its convex surface facing the object side, a positive lens (L 5 ) having its surface of sharper curvature facing the image side, a negative lens (L 6 ) separated therefrom or cemented thereto and having its surface of sharper curvature facing the object side, a biconcave lens (L 7 ) and a biconvex lens (L 8 ) cemented thereto.