Zoom lens

Claim 2

A zoom lens comprising a front negative grouping and a rear positive grouping, said groupings being axially movable at predetermined rates to vary the equivalent focal length while maintaining the position of the focal plane, said front grouping consisting of a front positive group including a positive front element, a rear positive group and a negative group therebetween.

Claim 3

The lens of claim 1 wherein said negative group comprises two menisci concave to the image.

Claim 4

The lens of claim 1 wherein said negative group comprises three menisci concave to the image.

Claim 5

The lens of claim 1 wherein said rear grouping comprises a first positive group and a second positive group, said first positive group having convex object and image side surfaces and including a bi-convex doublet.

Claim 6

The lens of claim 4 wherein the axial distance between the object and image side surfaces of said first group of said rear grouping is 0.25 to 0.75 of the shorter equivalent focal length of said lens.

Claim 7

The lens of claim 1 wherein said front positive group comprises a positive element convex to the object, said rear positive group comprising an element convex to the object, and said negative group having a front side convex to the object and a rear side concave to the image.

Claim 8

The lens of claim 1 wherein the ratio of the equivalent focal length of said first positive group of said front grouping to the equivalent focal length of the rear positive group of said front grouping is 2.0 to 5.0.

Claim 9

The lens of claim 1 wherein the equivalent focal length of the first positive group of the first grouping is at least five times the lower equivalent focal length of said lens.

Claim 10

The lens of claim 1 wherein the foremost negative element on the object end of said first grouping has an equivalent focal length whose absolute value is from one to two times the lower limit equivalent focal length of said lens.

Claim 11

The lens of claim 1 wherein the axial spacing between said rear positive group of said front grouping and the preceding negative element is between 0.1 and 0.25 of the lower limit equivalent focal length of said lens.

Claim 12

The lens of claim 2 as scaled to an equivalent focal length of 24.5 to 47.0 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 138.914 L1 4.311 1.723 38.0 R2 5555.863 .100 R3 81.344 L2 3.494 1.743 49.2 R4 19.449 9.955 R5 243.412 L3 2.500 1.620 60.3 R6 28.774 3.383 R7 28.163 L4 4.000 1.757 31.8 R8 59.412 25.302 R9 45.909 L5 11.122 1.582 42.0 R10 -19.127 L6 2.100 1.785 25.7 R11 -45.507 2.000 R12 19.705 L7 3.500 1.593 35.5 R13 144.587 1.814 R14 -226.943 L8 4.305 1.785 26.9 R15 19.181 2.922 R16 158.438 L9 2.193 1.804 46.5 R17 -35.460 ______________________________________ where L1-L9 are lens elements with surfaces defined on radii R1-R7, N d and V d are the indexes of refraction and Abbe numbers, respectively, as determined from the glass identification number, and where the axial distance between surfaces R8 and R9 varies with equivalent focal length.

Claim 13

The lens of claim 2 as scaled to an equivalent focal length of 24.5 to 47.5 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 78.741 L1 4.311 1.621 62.4 R2 423.928 0.100 R3 74.864 L2 3.444 1.804 46.5 R4 20.421 8.562 R5 351.059 L3 2.500 1.627 59.1 R6 26.808 5.218 R7 29.438 L4 4.000 1.762 28.6 R8 66.197 26.357 R9 51.010 L5 15.146 1.599 39.8 R10 -19.747 L6 2.100 1.790 25.5 R11 -41.271 2.000 R12 18.823 L7 3.500 1.603 37.7 R13 123.648 1.062 R14 -105.973 L8 5.319 1.798 25.5 R15 19.915 2.213 R16 -482.108 L9 2.193 1.844 45.6 R17 -30.111 ______________________________________ where L1-L9 are lens elements with surfaces defined on radii R1-R17, N d and V d are the indexes of refraction and Abbe numbers, respectively, of lens elements L1-L9 as determined from the glass identification number, and where the axial distance between surfaces R8 and R9 varies with equivalent focal length.

Claim 14

The lens of claim 2 as scaled to an equivalent focal length of 24.5 to 47.0 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 138.914 L1 4.311 1.723 38.0 R2 -4499.984 0.200 R3 81.344 L2 3.494 1.743 49.2 R4 19.449 9.955 R5 243.411 L3 2.500 1.620 60.3 R6 28.774 4.278 R7 28.163 L4 4.000 1.757 31.8 R8 59.412 26.678 R9 70.251 L5 4.000 1.582 42.0 R10 405.396 1.000 R11 48.480 L6 2.500 1.757 26.9 R12 15.070 L7 3.400 1.584 41.6 R13 -385.591 1.700 R14 19.361 L8 3.500 1.593 35.5 R15 194.059 1.814 R16 872.546 L9 6.633 1.785 26.1 R17 19.239 2.922 R18 132.125 L10 2.193 1.804 46.5 R19 -36.867 ______________________________________ where L1-L10 are lens elements with surfaces defined on radii R1-R19, N d and V d are the indexes of refraction and Abbe numbers, respectively, of lens elements L1-L9 as determined from the glass identification number, and where the axial distance between surfaces R8 and R9 varies with equivalent focal length.

Claim 15

The lens of claim 2 as scaled to an equivalent focal length of 24.5 to 47.5 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 138.914 L1 4.31 1.723 38.0 R2 1344.100 .20 R3 81.344 L2 3.49 1.743 49.2 R4 23.258 9.96 R5 243.411 L3 2.50 1.773 49.6 R6 24.659 3.98 R7 28.163 L4 4.00 1.699 30.1 R8 115.448 28.03 R9 57.556 L5 5.00 1.589 42.0 R10 -17.206 L6 1.80 1.805 25.5 R11 -31.637 1.00 R12 19.584 L7 3.50 1.673 32.2 R13 158.949 .61 R14 -133.809 L8 4.57 1.805 25.5 R15 23.426 1.65 R16 57.142 1.805 25.5 L9 2.97 R17 25.594 1.67 R18 504.434 L10 3.70 1.670 47.2 R19 -25.540 ______________________________________ where L1-L10 are lens elements with surfaces defined on radii R1-R19, N d and V d are the indexes of refraction and Abbe numbers, respectively, of lens elements L1-L9 as determined from the glass identification number, and where the axial distance between surfaces R8 and R9 varies with equivalent focal length.

Claim 16

The lens of claim 2 as scaled to an equivalent focal length of 24.5 to 47.0 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 138.914 L1 4.311 1.723 38.0 R2 990.767 0.200 R3 81.344 L2 3.494 1.743 49.2 R4 20.721 9.955 R5 243.411 L3 2.500 1.773 49.6 R6 27.546 2.991 R7 28.163 L4 4.000 1.699 30.1 R8 135.640 29.281 R9 53.061 L5 4.500 1.589 41.0 R10 -17.264 L6 1.800 1.805 25.5 R11 -31.658 1.004 R12 19.357 L7 3.500 1.673 32.2 R13 161.010 0.613 R14 -128.704 L8 4.567 1.805 25.5 R15 23.528 1.853 R16 61.099 L9 2.000 1.805 25.5 R17 24.798 1.705 R18 838.558 L10 3.700 1.670 47.2 R19 -24.833 ______________________________________ where L1-L10 are lens elements with surfaces defined on radii R1-R9, N d and V d are the indexes of refraction and Abbe numbers, respectively, of lens elements L1-L9 as determined from the glass identification number, and where the axial distance between surfaces R8 and R9 varies with equivalent focal length.

Claim 17

The lens of claim 3 as scaled to an equivalent focal length of 24.5 to 47.5 mm for a 24×36 mm image frame, substantially as described below: ______________________________________ Surface Axial Distance Radius (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 56.156 L1 7.293 1.517 64.2 R2 320.266 .100 R3 83.131 L2 3.444 1.804 46.5 R4 25.469 5.142 R5 75.186 L3 2.000 1.804 46.5 R6 28.026 2.864 R7 63.621 L4 2.500 1.643 48.0 R8 26.621 4.844 R9 30.017 L5 4.000 1.805 25.5 R10 75.243 28.258 R11 55.230 L6 14.150 1.603 38.0 R12 -18.062 L7 2.100 1.805 25.5 R13 -38.684 2.000 R14 18.81 L8 3.500 1.596 39.2 R15 116.243 1.062 R16 -102.385 L9 5.319 1.785 25.7 R17 20.230 2.213 R18 -232.898 L10 2.193 1.786 43.9 R19 -26.201 ______________________________________ where L1-L10 are lens elements with surfaces R1-R19, Nd and Vd are the indexes of refraction and Abbe numbers, respectively, of lens elements L1-L10 as determined from the glass identification number, and where the axial distance between surfaces R10 and R11 varies with equivalent focal length.

Claim 18

A zoom lens comprising a forward negative grouping and a rear positive grouping, said groupings being simultaneously movable at predetermined rates to vary the equivalent focal length of the lens, said forward grouping comprising from the object side a first positive element, a rear positive element convex to the object, and a negative group between said first and rear positive elements.

Claim 19

A zoom lens comprising a forward negative grouping and a rear positive grouping, said groupings being simultaneously movable at predetermined rates to vary the equivalent focal length of the lens, said forward grouping comprising from the object side a first positive element, a rear positive element convex to the object, and a negative group between said first and rear positive elements.

Claim 20

The lens of claim 17 where the equivalent focal length of the first positive element is about twice the lower limit equivalent focal length of the overall lens.

Claim 21

The lens of claim 17 where the ratio of equivalent focal length of said first positive element to the rear positive element is 2.0 to 5.0.

Claim 22

The lens of claim 17 where the equivalent focal length of said first positive element is 5.0 to 10.0 of the lower limit equivalent focal length of the lens.

Claim 23

The lens of claim 17 wherein the foremost negative element on the object end of said first grouping has an equivalent focal length whose absolute value is from one to two times the lower limit equivalent focal length of said lens.

Claim 24

The lens of claim 17 where the axial spacing between said rear positive element and the preceding negative element is 0.1 to 0.25 of the lower limit equivalent focal length of the lens.

Claim 25

The lens of claim 17 where said first positive element has an axial thickness of 0.15 to 0.35 of the lower limit equivalent focal length of the lens.

Claim 26

The lens of claim 17 where said first and rear positive elements are convex to the object and said negative group has a convex object side and a concave image side.

Claim 27

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front group comprising a front positive group having front positive elements, a rear positive group and a negative group therebetween, said rear grouping comprising a first positive group and a second positive group, said first positive group having convex object and image surfaces and including a bi-convex doublet, the axial distance between the object and image side surfaces of said first positive group being 0.25 to 0.75 of the lower limit equivalent focal length of said lens.

Claim 28

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front group comprising a front positive group having front positive elements, a rear positive group and a negative group therebetween, said rear grouping comprising a first positive group and a second positive group, said first positive group having convex object and image surfaces and including a bi-convex doublet, the axial distance between the object and image side surfaces of said first positive group being 0.25 to 0.75 of the lower limit equivalent focal length of said lens.

Claim 29

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the equivalent focal length of said rear positive group being about twice the lower limit equivalent focal length of the lens.

Claim 30

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the equivalent focal length of said rear positive group being about twice the lower limit equivalent focal length of the lens.

Claim 31

The lens of claim 26 where the equivalent focal length (F R ) of said rear positive group is 2.8F.sub.o > F.sub.R > 2F.sub.o where F o is the equivalent focal length of said lens.

Claim 32

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the ratio of the equivalent focal lengths of said front positive group to said rear positive group being 2.0 to 5.0.

Claim 33

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the ratio of the equivalent focal lengths of said front positive group to said rear positive group being 2.0 to 5.0.

Claim 34

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the ratio of the equivalent focal lengths of said front group to the lower limit equivalent focal length of the lens being 5.0 to 10.0.

Claim 35

A zoom lens comprising a front grouping of overall negative power and a rear grouping of overall positive power, said groups being axially movable at predetermined rates to vary the equivalent focal length of said lens while maintaining the position of the focal plane, said front grouping comprising a front positive group, a rear positive group and a negative group therebetween, the ratio of the equivalent focal lengths of said front group to the lower limit equivalent focal length of the lens being 5.0 to 10.0.