Zoom lens

Claim 2

A zoom lens having upper and lower limit equivalent focal lengths comprising from the object end, a first negative group and a second positive group, said groups being movable axially relative to each other to vary the equivalent focal length of the lens, the absolute value of the equivalent focal length of said first group |F 1 | being greater than the lower limit equivalent focal length of said lens, and 3>|F.sub.1 |/F.sub.2 ≧1.6 where F 2 is the equivalent focal length of said second group, the lower limit equivalent focal length of said lens being greater than the diagonal of the image frame of said lens, said first group consists of two elements, one of which is biconcave.

Claim 3

A zoom lens according to claim 1 where said first group consists of said biconcave element and a biconvex element.

Claim 4

A zoom lens according to claim 1 where said first group from the object end consists of said biconcave element and a positive meniscus concave to the object.

Claim 5

A zoom lens according to claim 1 where said first group from the object end consists of said biconcave element and a positive meniscus.

Claim 6

The zoom lens as in claim 1 wherein said second group comprises from the object end four elements, the first two of said elements being of positive power, followed by a negative element and finally a widely spaced positive element.

Claim 7

The zoom lens as in claim 1 wherein said second group comprises from the object end a singlet, a positive doublet, a thick long focal length meniscus doublet concave to the film plane, a meniscus singlet concave to the film plane, and a negative group widely separated from said meniscus singlet.

Claim 8

A zoom lens according to claim 1 where said second group comprises from the object end a bi-concave element, a bi-convex doublet, a positive doublet in the form of a meniscus convex to the object, a negative meniscus concave to the object, and a bi-convex element.

Claim 9

A zoom lens according to claim 2 where said second group consists from the object end of a bi-concave element, a positive meniscus convex to the object, a negative meniscus concave to the image, and a positive element convex to the object.

Claim 10

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 70-145 mm substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -96.483 L1 3.80 1.815 43.2 R2 = 93.362 1.13 R3 = 94.885 L2 7.96 1.674 31.9 R4 = -225.454 2 R5 = 48.984 L3 6.08 1.700 54.7 R6 = -350.307 .30 R7 = 36.342 L4 5.31 1.675 48.4 R8 = 277.063 .76 R9 = -1107.411 L5 12.47 1.754 27.6 R10 = 22.283 8.31 R11 = 49.921 L6 6.82 1.802 25.6 R12 = 75.151 ______________________________________ GROUP SPACING EFL Z FVD f/No. ______________________________________ 70.0mm 75.92mm 190.6mm 2.8 92.0mm 41.09 165.9 3.2 145.0mm .50 149.8 4.0 ______________________________________ where L1-L6 are the lens elements from the object end to the image end, R1-R12 are the surfaces of elements L1-L6, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, Z is a variable lens spacing, EFL is the equivalent focal length of the lens, FVD is the front vertex distance of the lens, and f/No. is the relative aperture of the lens.

Claim 11

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 50-192 mm substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -81.235 L1 2.50 1.729 53.4 R2 = 64.727 .19 R3 = 64.688 L2 4.50 1.813 25.3 R4 = 230.458 Z1 R5 = 116.205 L3 6.50 1.560 61.4 R6 = -118.230 .15 R7 = 59.886 L4 12.50 1.489 70.2 R8 = -96.191 L5 2.00 1.813 25.3 R9 = 557.537 .15 R10 = 28.530 L6 15.40 1.489 70.2 R11 = 410.187 L7 3.20 1.633 48.6 R12 = 25.976 2.95 R13 = 37.520 L8 5.74 1.489 70.2 R14 = 105.944 Z2 R15 = -19.584 L9 2.33 1.614 59.5 R16 = -40.587 .20 R17 = 103.944 L10 3.76 1.792 25.5 R18 = -781.970 ______________________________________ GROUP SPACING EFL Z1 Z2 FVD f/No. ______________________________________ 50.0mm 67.831 22.834 172.1 4.0 75.0mm 39.358 21.846 158.8 4.0 135.0mm 12.593 22.208 167.0 4.0 192.0mm 2.696 22.925 190.0 4.0 ______________________________________ where L1-L10 are the lens elements from the object end to the image end, R1-R18 are the surfaces of elements L1-L10, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, Z1 and Z2 are the variable lens spacings, EFL is the equivalent focal length of the lens, FVD is the front vertex distance of the lens, and f/No. is the relative aperture of the lens.

Claim 12

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 76.5-192.1 mm substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -88.100 L1 2.50 1.642 59.9 R2 = 67.104 .19 R3 = 64.014 L2 4.50 1.812 25.2 R4 = 136.313 Z R5 = 134.983 L3 6.50 1.609 56.4 R6 = -159.956 .15 R7 = 58.708 L4 12.50 1.489 70.2 R8 = -98.315 L5 2.0 1.812 25.2 R9 = 573.019 .15 R10 = 28.413 L6 15.40 1.489 70.2 R11 = 335.947 L7 3.20 1.646 47.6 R12 = 25.535 2.95 R13 = 35.799 L8 5.74 1.489 70.2 R14 = 110.481 6.02 Aperture 15.80 R15 = -20.282 L9 2.33 1.605 60.4 R16 = -40.780 .20 R17 = 142.976 L10 3.76 1.791 25.4 R18 = -296.675 105.69 ______________________________________ GROUP SPACING EFL Z FVD f/No. ______________________________________ 76.5mm 44.107mm 166.5m 4.0 129.2mm 15.649 168.6 4.0 192.0mm 2.100 191.7 4.0 ______________________________________ where L1-L10 are the lens elements from the object end to the image end, R1-R18 are the surfaces of elements L1-L10, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, Z1 is a variable lens spacing, EFL is the equivalent focal length of the lens, FVD is the front vertex distance of the lens, and f/No. is the relative aperture of the lens.

Claim 13

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 50-120 mm substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -65.1214 L1 2.5000 1.633 53.5 R2 = 49.9779 .2000 R3 = 49.7071 L2 4.4988 1.803 26.0 R4 = 123.0426 Z = 30.0 to 1.0 R5 = 95.5044 L3 5.6086 1.720 50.4 R6 = -89.8393 .2000 R7 = 51.9336 L4 10.1667 1.487 70.4 R8 = -56.2006 L5 2.0000 1.805 25.5 R9 = 242.1799 .2000 R10 = 35.4902 L6 9.9112 1.505 60.6 R11 = -63.9444 L7 2.0000 1.720 50.4 R12 = 67.8449 9.7716 R13 = 89.2652 L8 3.6997 1.531 51.3 R14 = -75.4657 2.000 Aperture 24.2395 R15 = -19.5383 L9 1.5811 1.720 50.4 R16 = 211.1908 .2000 R17 = 72.5994 L10 8.000 1.805 25.5 R18 = -198.3869 ______________________________________ BFL = 40.0mm where L1-L10 are lens elements from the object end to the image end, R1-R18 are the surfaces of elements L1-L10, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, and Z denotes a space which varies with change in equivalent focal length.

Claim 14

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 70 to 145 substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -96.5620 L1 2.2900 1.847 23.8 R2 = -67.5590 3.7200 R3 = -64.8290 L2 2.1500 1.697 55.5 R4 = 2317.6220 Z = 65.56 to .5 R5 = 70.8430 L3 4.2600 1.518 59.0 R6 = -258.1480 .5000 R7 = 48.0200 L4 3.9000 1.517 64.2 R8 = 204.8770 3.3500 Aperture .5000 R9 = 37.4330 L5 9.2300 1.583 46.4 R10 = 200.0540 1.0900 R11 = 639.6840 L6 12.0000 1.847 23.8 R12 = 23.1000 21.7800 R13 = 56.0900 L7 2.2300 1.847 23.8 R14 = 138.5020 ______________________________________ where L1-L7 are lens elements from the object end to the image end, R1-R14 are the surfaces of elements L1-L10, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, and Z denotes a space which varies with change in equivalent focal length.

Claim 15

A lens according to claim 1 scaled to an image frame of 24×36 mm and an EFL of 77-145 mm substantially as follows: ______________________________________ Ele- Radius of Axial Distance ment Curvature (mm) Between Surfaces (mm) N.sub.d V.sub.d ______________________________________ R1 = -246.583 L1 3.000 1.806 40.7 R2 = 47.217 2.199 R3 = 49.870 L2 4.110 1.728 28.3 R4 = 295.575 Z R5 = 46.962 L3 6.376 1.658 50.9 R6 = -299.223 0.200 R7 = 32.687 L4 6.539 1.720 50.3 R8 = 98.647 4.738 R9 = plano L5 2.500 1.805 25.5 R10 = 23.887 4.000 Aperture 26.177 R11 = 91.566 L6 3.000 1.603 38.0 R12 = -276.325 ______________________________________ GROUP SPACING EFL Z FVD f/No. ______________________________________ 77.25mm 62.39mm 199.0 3.4 105.0 28.17 181.4 3.9 145.0 1.88 179.0 4.6 ______________________________________ where L1-L7 are lens elements from the object end to the image end, R1-R14 are the surfaces of elements L1-L7, N d is the index of refraction of the lens elements, V d is the dispersion of the lens elements as measured by the Abbe number, and Z denotes a space which varies with change in equivalent focal length.