Zoom lens

Claim 2

A zoom lens comprising from the object end to the image end a first positive group, said first group comprising a doublet component and a singlet component, said first group being axially movable to focus the lens, a second negative group, said first and second groups being axially movable in predetermined relation to vary the equivalent focal length of the lens; and a third stationary positive group, the zoom lens satisfying the following relations, 0.2<F.sub.1 /F.sub.L <0.6 0.2<K.sub.D /K.sub.S <1.6 where F 1 is the equivalent focal length of the first groups, F L is the longest equivalent focal length of the zoom lens, K D is the optical power of the doublet component of the first group, and K S is the optical power of the singlet component of the first group.

Claim 3

A lens according to claim 1, wherein said second group consists of a negative singlet followed by a negative doublet.

Claim 4

A lens according to claim 1 wherein said second group consists of a negative doublet followed by a negative singlet.

Claim 5

A lens according to claim 1 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a singlet followed by a doublet.

Claim 6

A lens according to claim 1 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a doublet followed by a singlet.

Claim 7

A lens according to claim 1 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a singlet followed by a doublet followed by a singlet.

Claim 8

A lens according to claim 1 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of two singlets.

Claim 9

A lens according to claim 1 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a doublet.

Claim 10

A lens according to claim 1 scaled to an EFL of 72.0 mm to 195.8 mm substantially as described: ______________________________________ Axial Distance Index of Between Refrac- Abbe Ele- Radius of Surfaces tion No. ment Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 100.61 L1 6.50 1.500 66.4 R2 = -208.00 .20 R3 = 108.10 L2 8.10 1.534 62.0 R4 = -130.00 L3 3.50 1.797 25.8 R5 = 965.06 Z1 R6 = -608.86 L4 2.30 1.794 48.2 R7 = 21.02 L5 5.10 1.847 23.9 R8 = 47.40 3.81 R9 = -61.93 L6 2.00 1.815 44.9 R10 = -717.67 Z2 R11 = 58.55 L7 3.70 1.742 49.1 R12 = -206.21 .20 R13 = 27.13 L8 6.80 1.487 68.4 R14 = -73.05 .59 R15 = -74.44 L9 3.00 R16 = 83.46 36.59 R17 = -16.48 L10 2.00 1.843 38.7 R18 = -31.29 .20 R19 = 144.41 L11 3.40 1.796 25.5 R20 = -79.57 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 72.0 1.50 41.00 169.47 134.9 25.84 21.49 174.25 195.8 34.46 2.55 163.89 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R20, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 11

A lens according to claim 1 scaled to an EFL of 70.0 mm to 199.9 mm substantially as described: ______________________________________ Axial Index of Distance Refrac- Abbe Ele- Radius of Between Sur- tion No. ment Curvature (mm) faces (mm) N.sub.d V.sub.d ______________________________________ R1 = 78.89 L1 3.50 1.805 25.5 R2 = 42.10 L2 9.00 1.665 51.7 R3 = 6349.49 .35 R4 = 74.28 L3 6.00 1.482 71.1 R5 = -2197.53 Z1 R6 = -277.73 L4 2.00 1.785 48.5 R7 = 48.38 4.80 R8 = -100.61 L5 2.00 1.745 48.5 R9 = 28.54 L6 4.00 1.817 25.0 R10 = 201.69 Z2 R11 = 80.69 L7 3.50 1.487 70.4 R12 = -195.77 .20 R13 = 32.44 L8 6.50 1.487 70.4 R14 = -90.94 L9 1.50 1.793 26.0 R15 = 212.82 32.94 R16 = 225.23 L10 5.00 1.805 25.5 R17 = -131.05 8.02 R18 = -24.27 L11 2.00 1.809 40.4 R19 = -55.49 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 70.0 .50 71.45 212.94 135.0 15.31 35.97 192.27 199.9 20.50 .50 161.95 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R19, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 12

A lens according to claim 1 scaled to an EFL of 72.2 mm to 193.7 mm substantially as described: ______________________________________ Axial Distance Index of Between Refrac- Abbe Ele- Radius of Surfaces tion No. ment Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 117.60 L1 3.00 1.785 26.1 R2 = 60.14 L2 8.10 1.517 64.2 R3 = -343.26 .10 R4 = 75.57 L3 6.00 1.517 64.2 R5 = -960.00 Z1 R6 = -773.48 L4 2.00 1.720 50.3 R7 = 55.15 3.85 R8 = -78.38 L5 2.00 1.743 49.2 R9 = 32.58 L6 5.05 1.805 25.5 R10 = 219.88 Z2 R11 = 45.80 L7 5.10 1.667 48.3 R12 = -160.00 .20 R13 = 36.25 L8 5.40 1.517 64.2 R14 = -188.96 L9 1.50 1.805 25.5 R15 = 101.76 3.22 R16 = -169.64 L10 2.00 1.805 25.5 R17 = 270.68 42.53 R18 = -18.37 L11 2.00 1.743 49.2 R19 = -38.30 .20 R20 = 117.60 L12 3.90 1.626 35.7 R21 = -76.42 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 72.2 1.46 59.14 195.79 135.2 21.38 29.25 185.81 193.7 28.26 1.45 164.89 ______________________________________ where the lens comprises lens elements L1 to L12 having surfaces R1 to R21, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), the FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 13

A lens according to claim 1 scaled to an EFL of 70.0 mm to 199.9 mm substantially as described: ______________________________________ Axial Index of Distance Refrac- Abbe Ele- Radius of Between Sur- tion No. ment Curvature (mm) faces (mm) N.sub.d V.sub.d ______________________________________ R1 = 60.78 L1 3.50 1.837 23.6 R2 = 35.72 L2 9.00 15.54 59.5 R3 = -1501.55 .35 R4 = 37.45 L3 7.00 1.485 68.5 R5 = -807.56 Z1 R6 = -260.37 L4 2.00 1.728 54.7 R7 = 28.81 4.00 R8 = -61.32 L5 1.80 1.788 43.4 R9 = 21.60 L6 4.50 1.854 23.1 R10 = 151.89 Z2 R11 = 50.66 L7 8.50 1.492 65.4 R12 = -27.43 L8 1.50 1.849 23.1 R13 = -66.89 9.99 R14 = 91.86 L9 5.00 1.794 34.7 R15 = -84.59 25.25 R16 = -29.20 L10 2.00 1.860 42.5 R17 = 42.78 L11 4.00 1.634 49.8 R18 = -34.10 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 70.0 .88 46.23 202.87 135.0 10.12 23.36 189.23 199.9 13.36 .50 169.56 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R18, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 14

A lens according to claim 1 scaled to an EFL of 71.0 mm to 197.0 mm substantially as described: ______________________________________ Axial Distance Index of Between Refrac- Abbe Ele- Radius of Surfaces tion No. ment Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 81.68 L1 3.50 1.805 25.5 R2 = 42.51 L2 9.50 1.658 50.9 R3 = -676.67 .35 R4 = 77.45 L3 5.50 1.487 70.4 R5 = 1302.78 Z1 R6 = -470.54 L4 2.00 1.743 49.2 R7 = 47.24 4.80 R8 = -80.37 L5 2.00 1.743 49.2 R9 = 28.12 L6 5.00 1.805 25.5 R10 = 186.79 Z2 R11 = 60.07 L7 3.50 1.487 70.4 R12 = -184.06 .20 R13 = 34.35 L8 6.50 1.487 70.4 R14 = -75.82 L9 1.50 1.728 28.3 R15 = 192.84 48.78 R16 = -19.45 L10 2.00 1.806 40.7 R17 = -42.98 .30 R18 = 186.54 L11 4.00 1.717 29.5 R19 = -75.15 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 71.0 1.50 66.39 207.32 135.0 15.96 33.69 189.08 197.97 21.07 1.50 161.98 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R19, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 15

A lens according to claim 1 scaled to an EFL of 72.0 mm to 196.1 mm substantially as described: ______________________________________ Axial Distance Index of Between Refrac- Abbe Ele- Radius of Surfaces tion No. ment Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 96.76 L1 6.50 1.517 64.2 R2 = -187.65 .20 R3 = 93.47 L2 8.10 1.517 64.2 R4 = -116.67 L3 3.50 1.755 27.5 R5 = 589.22 Z1 R6 = 557.43 L4 2.00 1.691 54.7 R7 = 41.20 4.00 R8 = -49.37 L5 2.00 1.640 60.2 R9 = 25.90 L6 5.35 1.679 30.8 R10 = 522.41 Z2 R11 = 52.43 L7 3.70 1.565 48.2 R12 = -126.28 .20 R13 = 32.66 L8 6.80 1.517 64.2 R14 = -71.33 L9 2.73 1.785 25.7 R15 = 99.30 43.53 R16 = -18.06 L10 2.00 1.744 44.9 R17 = -38.92 .20 R18 = 151.19 L11 3.40 1.663 32.8 R19 = -66.42 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 72.0 1.50 45.48 183.21 135.0 22.74 23.14 182.105 196.1 30.29 1.50 168.03 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R19, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 16

A lens according to claim 1 scaled to an EFL of 70.0 mm to 200.1 mm substantially as described: ______________________________________ Axial Index of Distance Refrac- Abbe Ele- Radius of Between Sur- tion No. ment Curvature (mm) faces (mm) N.sub.d V.sub.d ______________________________________ R1 = 62.78 L1 3.50 1.837 23.6 R2 = 39.20 L2 8.00 1.585 56.1 R3 = 1101.93 .35 R4 = 59.82 L3 5.00 1.469 71.0 R5 = -965.01 Z1 R6 = -1904.32 L4 4.50 1.849 23.2 R7 = -55.47 L5 1.80 1.697 63.2 R8 = 41.13 4.00 R9 = -52.09 L6 2.00 1.670 58.6 R10 = 121.67 Z2 R11 = 43.19 L7 8.50 1.492 65.4 R12 = -27.18 L8 1.50 1.849 23.1 R13 = -79.28 16.06 R14 = 112.81 L9 5.00 1.839 30.6 R15 = -63.60 17.00 R16 = -29.31 L10 2.00 1.744 48.8 R17 = 47.23 L11 4.00 1.491 76.1 R18 = -45.85 ______________________________________ EFL (mm) Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 70.0 .50 60.85 210.27 135.0 13.15 30.67 192.67 200.1 17.57 .50 167.05 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R18, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 17

A lens according to claim 1 scaled to an EFL of 60.0 mm to 172.0 mm substantially as described: ______________________________________ Axial Distance Radius of Between Surfaces Element Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 67.35 L1 2.18 1.785 26.1 R2 = 41.97 L2 4.79 1.487 70.4 R3 = -410.49 .07 R4 = 68.06 L3 3.63 1.487 70.4 R5 = -582.10 Z1 R6 = -459.30 L4 1.45 1.773 49.6 R7 = 59.03 3.30 R8 = -91.54 L5 Z2 R9 = 23.13 L6 2.97 1.805 25.5 R10 = 84.79 .15 R11 = 47.33 L7 3.63 1.521 49.0 R12 = -118.13 .15 R13 = 43.69 L8 3.63 1.486 68.2 R14 = -61.11 L9 1.09 1.805 25.5 R15 = 120.59 1.96 Aperture 42.21 R16 = -17.52 L10 1.45 1.773 49.6 R17 = -29.49 .08 R18 = 99.77 L11 2.18 1.706 30.6 R19 = -207.96 ______________________________________ Zoom Spacing 60.0 mm 100.0 mm 172.0 mm ______________________________________ Z1 1.8 mm 10.9 mm 16.5 mm Z2 47.3 mm 30.8 mm .96 mm FVD 162.5 mm 155.1 mm 130.9 mm ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R19, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL).

Claim 18

A lens according to claim 1 scaled to an EFL of 80.27 mm to 230.1 mm. substantially as described: ______________________________________ Surface Radius Axial Distance Lens (mm) Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 67.35 L1 3.00 1.785 26.1 R2 = 41.97 L2 6.60 1.487 70.4 R3 = -410.49 .10 R4 = 68.06 L3 5.00 1.487 70.4 R5 = -582.10 Z1 R6 = -459.30 L4 2.00 1.773 49.6 R7 = 59.03 2.47 R8 = -91.54 L5 2.00 R9 = 23.13 L6 4.55 1.743 49.2 R10 = 84.79 Z2 1.805 25.5 R11 = 47.33 L7 4.10 1.633 47.4 R12 = -118.13 .20 R13 = 43.69 L8 5.00 1.517 64.2 R14 = -611.11 L9 1.50 1.486 68.2 R15 = 120.59 2.69 Aperture 56.01 R16 = -21.05 L10 2.00 1.773 49.6 R17 = -46.95 .12 R18 = 87.94 L11 3.00 1.766 27.3 R19 = -590.13 ______________________________________ Zoom Spacing EFL mm Z.sub.1 (mm) Z.sub.2 (mm) FVD (mm) ______________________________________ 82.7 2.95 64.29 206.62 135.0 14.35 41.93 195.66 230.1 21.79 1.32 162.51 ______________________________________ where the lens comprises lens elements L1 to L11 having surfaces R1 to R19, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated focal length (EFL), and FVD is the front vertex distance, the distance between the front surface of L1 and the image plane, and all distances are given in millimeters (mm).

Claim 19

A lens according to claim 1 scaled to an EFL of 82.7 mm to 193.7 mm substantially as described: ______________________________________ Axial Distance Radius of Between Surfaces Element Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 66.44 L1 3.00 1.785 26.1 R2 = 43.22 L2 8.10 1.517 64.2 R3 = 203.20 .10 R4 = 80.51 L3 6.00 1.517 64.2 R5 = -580.67 Z1 R6 = 114.92 L4 2.00 1.773 49.6 R7 = 58.85 3.02 R8 = -78.60 L5 2.00 R9 = 23.35 L6 5.05 1.805 25.5 R10 = 66.13 Z2 R11 = 29.27 L7 8.50 1.569 56.0 R12 = -27.35 L8 1.50 1.785 25.7 R13 = -205.30 1.00 Aperture 14.40 R14 = 225.27 1.805 25.5 L9 3.60 R15 = -36.08 4.93 R16 = -21.59 L10 1.50 1.699 30.1 R17 = -313.89 ______________________________________ Zoom Spacing 82.7 mm 135.2 mm 193.7 mm ______________________________________ Z1 8.26 22.7 29.6 Z2 53.4 28.5 .687 FVD 196.2 185.8 164.8 ______________________________________ wherein the lens comprises lens elements L1 to L10 having surfaces R1 to R7, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL).

Claim 20

A lens according to claim 1 scaled to an EFL of 82.7 to 193.7 substantially as described: TABLE XI ______________________________________ Axial Distance Radius of Between Surfaces Element Curvature (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 61.9 L1 3.00 1.785 26.1 R2 = 39.40 L2 8.10 1.517 64.2 R3 = 143.15 .10 R4 = 69.85 L3 6.00 1.517 64.2 R5 = -366.91 Z1 R6 = 125.63 L4 2.00 1.834 37.3 R7 = 65.49 3.85 R8 = -79.89 L5 2.00 1.756 48.3 R9 = 22.26 L6 5.05 R10 = 66.31 Z2 Aperture .50 R11 = 27.73 L7 5.00 1.537 61.1 R12 = -78.71 .15 R13 = 23.40 L8 3.90 1.489 74.9 R14 = 67.23 1.30 R15 = -98.07 L9 2.40 1.660 33.4 R16 = 20.17 4.50 R17 = 222.67 L10 3.50 1.796 25.6 R18 = -134.85 ______________________________________ Zoom Spacing 82.6 mm 135.1 mm 193.6 mm ______________________________________ Z1 2.2 16.6 23.5 Z2 53.4 28.4 .7 FVD 196.2 185.7 164.8 ______________________________________ wherein the lens comprises lens elements L1 to L10 having surfaces R1 to R18, the index of refraction is given by N d , the dispersion is measured by the Abbe No. as given by V d , Z 1 and Z 2 are the variable air spacings at the indicated equivalent focal length (EFL).

Claim 21

A zoom lens comprising from the object end a first positive group, a second negative group and a third positive group, said first and second groups being axially movable in predetermined relation to vary the equivalent focal length of said lens, said first group being axially movable for focusing, said third group being stationary during change in equivalent focal length, and 2.0>K.sub.1 /K.sub.M >1.0 -6.0>K.sub.2 /K.sub.M >-3.0 3.0>K.sub.3 /K.sub.M >2.0 where K 1 , K 2 , and K 3 are the optical powers expressed as the reciprocal of the equivalent focal lengths in millimeters of the first, second and third groups, respectively, and K M is the geometric mean power of the lens.

Claim 22

A zoom lens comprising from the object end a first positive group, a second negative group and a third positive group, said first and second groups being axially movable in predetermined relation to vary the equivalent focal length of said lens, said first group being axially movable for focusing, said third group being stationary during change in equivalent focal length, and 2.0>K.sub.1 /K.sub.M >1.0 -6.0>K.sub.2 /K.sub.M >-3.0 3.0>K.sub.3 /K.sub.M >2.0 where K 1 , K 2 , and K 3 are the optical powers expressed as the reciprocal of the equivalent focal lengths in millimeters of the first, second and third groups, respectively, and K M is the geometric mean power of the lens.

Claim 23

The lens of claim 20 where said first group comprises a positive doublet and a positive singlet and 0.6>F.sub.1 /F.sub.L >0.2 1.6>K.sub.D /K.sub.S >0.2 where F 1 is the equivalent focal length of the first group; F L is the maximum equivalent focal length of the lens; K D is the optical power of the doublet; and K S is the optical power of the singlet.

Claim 24

The lens of claim 20 where the telephoto ratio of the third group is less than 1.4.

Claim 25

A zoom lens comprising from the object end a first positive group, a second negative group, and a third positive group, said first group being axially movable to focus the lens, said first and second groups being axially movable in predetermined relationship to vary the equivalent focal length of the lens, said third lens group being stationary, said first, second, and third groups having optical powers K 1 , K 2 , and K 3 , respectively, and 2.0>K.sub.1 /K.sub.M >1.0 -6.0>K.sub.2 /K.sub.M >-3.0 3.0>K.sub.3 /K.sub.M >2.0 where K M is the geometrical means of the extreme equivalent focal lengths of the lens, and 0.6>F.sub.1 /F.sub.L >0.2 where F 1 is the equivalent focal length of the first group, and F L is the longest equivalent focal length of the lens.

Claim 26

A zoom lens comprising from the object end a first positive group, a second negative group, and a third positive group, said first group being axially movable to focus the lens, said first and second groups being axially movable in predetermined relationship to vary the equivalent focal length of the lens, said third lens group being stationary, said first, second, and third groups having optical powers K 1 , K 2 , and K 3 , respectively, and 2.0>K.sub.1 /K.sub.M >1.0 -6.0>K.sub.2 /K.sub.M >-3.0 3.0>K.sub.3 /K.sub.M >2.0 where K M is the geometrical means of the extreme equivalent focal lengths of the lens, and 0.6>F.sub.1 /F.sub.L >0.2 where F 1 is the equivalent focal length of the first group, and F L is the longest equivalent focal length of the lens.

Claim 27

The lens of claims 1, 20, or 23, where the telephoto ratio of the third group of said lens is less than 1.3.

Claim 28

The lens of claim 23 wherein the first group consists of a positive doublet and a positive singlet, and 1.6>K.sub.D /K.sub.S >0.2 where K D is the optical power of the doublet and K S is the optical power of the singlet.

Claim 29

A lens according to claim 23 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a singlet followed by a doublet.

Claim 30

A lens according to claim 23 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a doublet followed by a singlet.

Claim 31

A lens according to claim 23 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a singlet followed by a doublet followed by a singlet.

Claim 32

A lens according to claim 23 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of two singlets.

Claim 33

A lens according to claim 23 wherein said third group comprises a positive subgroup at the object side widely spaced from a negative subgroup and the positive subgroup consists of a doublet.