Wide angle lens

Claim 2

A wide angle lens of the retrofocus type comprising from the object end to the image end a first negative group, a second negative group, a third positive group, a fourth negative group, a fifth positive group, a sixth negative group, a seventh positive group, an eighth positive group and a ninth positive group, said eighth and ninth groups having a combined equivalent focal length opposite in sign to and having an absolute value within 10 percent of the combined equivalent focal lengths of said first and second groups.

Claim 3

A wide angle lens as defined in claim 1 wherein each of said fifth group, said sixth group, said seventh group and said eighth group comprises a doublet.

Claim 4

A wide angle lens as defined in claim 2 wherein said fifth group has a lens element on the image side thereof having a thickness greater than seven-tenths the equivalent focal length of said element.

Claim 5

A wide angle lens as defined in claim 2 wherein the lens elements comprising the doublet of said sixth lens group have indices of refraction that are substantially the same, and Abbe numbers having a large difference.

Claim 6

A wide angle lens as defined in claim 1 further comprising an aperture-determining means situated between said sixth group and said seventh group.

Claim 7

A wide angle lens as defined in claim 1 wherein the first group and the second group have equivalent focal lengths having the relationship 0.95 |F L1 | ≦ |F L2 | ≦ 1.05 |F L1 |, wherein |F L1 | is the absolute value of the equivalent focal length of the first group and |F L2 | is the absolute value of the equivalent focal length of the second group.

Claim 8

A wide angle lens as defined in claim 1 wherein the third group and the fourth group have equivalent focal lengths that differ in sign and have the relationship 0.85 |F L3 | ≦ |F L4 | ≦ 1.15 |F L3 |, wherein |F L3 | is the absolute value of the equivalent focal length of the third group and |F L4 | is the absolute value of the equivalent focal length of the fourth group.

Claim 9

A wide angle lens as defined in claim 1 wherein the eighth and ninth groups have a combined equivalent focal length of between 1.4 and 1.7 times the equivalent focal length of said lens.

Claim 10

A wide angle lens as defined in claim 1 wherein said lens has a field angle of substantially 100°, a relative aperture of F/2.8 and a ratio of back focal length to equivalent focal length of greater than two.

Claim 11

A wide angle lens as defined in claim 1 wherein said lens moves as a whole during focusing travel, said lens further having an axial spacing between groups seven and eight, said spacing varying during focusing travel to permit close focusing.

Claim 12

A wide angle lens as defined in claim 10 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame: ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 38.166 mm L1 2.30 mm 1.804 46.5 R2 = 20.917 6.27 R3 = 44.249 L2 2.20 1.804 46.5 R4 = 22.445 7.87 R5 = 44.082 L3 6.21 1.834 37.3 R6 = -92.683 0.10 R7 = 29.496 L4 1.50 1.620 60.3 R8 = 11.914 3.51 R9 = 101.696 L5 1.20 1.804 46.5 R10 = 15.113 L6 13.20 1.487 70.4 R11 = -15.113 1.51 R12 = -20.223 L7 1.20 1.640 60.2 R13 = 11.526 L8 4.40 1.620 36.3 R14 = -46.994 1.50 R15 = 21.805 L9 7.24 1.613 37.0 R16 = -49.501 L10 4.77 1.805 25.5 R17 = 33,405 R18 = 186.360 2.00 L11 1.20 1.805 25.5 R19 = 23.403 L12 5.06 1.569 63.1 R20 = -19.553 0.10 R21 = 674.33 L13 2.86 1.804 46.5 R22 = -42.191 ______________________________________ BFL = 39.6 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further having an aperture stop situated between said elements L8 and L9.

Claim 13

A wide angle lens as defined in claim 10 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame. ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 34.666 mm L1 2.50 mm 1.804 46.5 R2 = 19.851 6.18 R3 = 40.109 L2 2.50 1.804 46.5 R4 = 21.320 6.14 R5 = 40.941 L3 5.53 1.834 37.3 R6 = -114.274 0.10 R7 = 28.479 L4 1.50 1.620 60.3 R8 = 11.576 3.46 R9 = 124.245 L5 1.20 1.804 46.5 R10 = 15.670 L6 12.61 1.487 70.4 R11 = -14.946 1.12 R12 = -23.332 L7 1.20 1.640 60.2 R13 = 11.206 L8 4.27 1.620 36.3 R14 = -74.899 1.86 R15 = 24.760 L9 7.978 1.613 37.0 R16 = -51.619 L10 6.797 1.805 25.5 R17 = 45.297 1.755 R18 = -69.165 L11 1.20 1.805 25.5 R19 = 27.831 L12 4.90 1.569 63.1 R20 = -19.614 0.10 R21 = 125.497 L13 3.29 1.804 46.5 R22 = -45.886 ______________________________________ BFL = 39.62 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces and according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further having an aperture stop between said elements L8 and L9.

Claim 14

A wide angle lens as defined in claim 10 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame: ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 37.687 mm L1 2.50 mm 1.804 46.5 R2 = 20.590 6.32 R3 = 44.147 L2 2.50 1.804 46.5 R4 = 22.138 7.47 R5 = 41.270 L3 5.10 1.834 37.3 R6 = -99.692 0.10 R7 = 29.488 L4 1.50 1.620 60.3 R8 = 11.914 3.59 R9 = 121.772 L5 1.20 1.804 46.5 R10 = 15.490 L6 13.27 1.487 70.4 R11 = -15.184 1.65 R12 = -20.452 L7 1.20 1.640 60.2 R13 = 11.716 L8 4.1 1.620 36.3 R14 = -50.477 1.50 R15 = 22.659 L9 7.38 1.613 37.0 R16 = -43.247 L10 6.13 1.805 25.5 R17 = 36.689 1.57 R18 = -212.451 L11 1.20 1.805 25.5 R19 = 23.915 L12 4.86 1.569 63.1 R20 = -20.039 0.10 R21 = 422.791 L13 2.95 1.804 46.5 R22 = -41.575 ______________________________________ BFL = 39.62 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further comprising an aperture stop situated between elements L8 and L9.

Claim 15

A wide angle lens as defined in claim 10 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame: ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 37.743 mm L1 2.50 mm 1.804 46.5 R2 = 20.766 6.00 R3 = 41.809 L2 2.50 1.804 46.5 R4 = 21.723 7.79 R5 = 41.399 L3 5.04 1.834 37.3 R6 = -101.957 0.10 R7 = 29.194 L4 1.50 1.620 60.3 R8 = 11.671 3.58 R9 = 118.52 L5 1.20 1.804 46.5 R10 = 15.540 L6 12.80 1.487 70.4 R11 = -15.075 1.37 R12 = -20.838 L7 1.20 1.640 60.2 R13 = 11.454 L8 5.18 1.620 36.3 R14 = -55.089 0.80 R15 = 22.705 L9 7.17 1.613 37.0 R16 = -43.192 L10 6.82 1.805 25.5 R17 = 37.393 1.57 R18 = -194.603 L11 1.20 1.805 25.5 R19 = 24.209 L12 4.84 1.569 63.1 R20 = -19.91 0.10 R21 = 371.888 L13 2.95 1.804 46.5 R22 = -41.912 ______________________________________ BFL = 39.62 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further comprising an aperture stop situated between said elements L8 and L9.

Claim 16

A wide angle lens as defined in claim 1 wherein said lens moves as a whole during focusing travel, said lens further having an axial spacing between groups four and five, said spacing varying during focusing travel to permit close focusing.

Claim 17

A wide angle lens as defined in claim 15 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame: ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 35.090 mm L1 2.50 mm 1.804 46.5 R2 = 19.740 6.21 R3 = 39.676 L2 2.50 1.804 46.5 R4 = 21.457 5.21 R5 = 41.114 L3 5.53 1.834 37.3 R6 = -118.448 0.10 R7 = 28.578 L4 1.50 1.620 60.3 R8 = 11.690 4.00 R9 = 161.824 L5 1.20 1.804 46.5 R10 = 16.025 L6 12.61 1.487 70.4 R11 = -14.996 1.39 R12 = -23.292 L7 1.20 1.640 60.2 R13 = 11.348 L8 4.27 1.620 36.3 R14 = -63.269 2.64 R15 = 24.967 L9 7.98 1.613 37.0 R16 = -54.338 L10 6.80 1.805 25.5 R17 = 43.169 1.07 R18 = -76.151 L11 1.20 1.805 25.5 R19 = 27.065 L12 4.90 1.569 63.1 R20 = -20.264 0.10 R21 = 142.684 L13 3.29 1.804 46.5 R22 = -40.880 ______________________________________ BFL = 39.62 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further having an aperture stop situated between said elements L8 and L9.

Claim 18

A wide angle lens as defined in claim 1 wherein said lens moves as a whole during focusing travel, said lens further having an axial spacing between groups six and seven, said spacing varying during focusing travel to permit close focusing.

Claim 19

A wide angle lens as defined in claim 17 defined substantially by the following data as scaled to an equivalent focal length of substantially 17mm for a 24 × 36mm image frame: ______________________________________ Axial Distance Lens Radius Between Surfaces N.sub.d V.sub.d ______________________________________ R1 = 35.647 mm L1 2.50 mm 1.804 46.5 R2 = 20.288 6.11 R3 = 41.245 L2 2.50 1.804 46.5 R4 = 20.880 5.94 R5 = 39.486 L3 5.53 1.834 37.3 R6 = -105.466 0.10 R7 = 29.517 L4 1.50 1.620 60.3 R8 = 11.158 3.63 R9 = 97.566 L5 1.20 1.804 46.5 R10 = 19.393 L6 12.61 1.487 70.4 R11 = -14.625 1.02 R12 = -20.310 L7 1.20 1.640 60.2 R13 = 13.872 L8 4.27 1.620 36.3 R14 = -48.039 2.73 R15 = 31.169 L9 7.98 1.613 37.0 R16 = -52.351 L10 6.80 1.805 25.5 R17 = 52.273 1.10 R18 = -56.801 L11 1.20 1.805 25.5 R19 = 32.257 L12 4.90 1.569 63.1 R20 = -19.412 0.10 R21 = 167.539 L13 3.29 1.804 46.5 R22 = -39.382 ______________________________________ BFL = 39.62 mm Where L1-L13 are successive lens elements arranged in nine groups as follows: L1; L2; L3; L4; L5, L6; L7, L8; L9, L10; L11, L12; L13; R1-R22 are the radii of curvature of the successive lens surfaces according to the sequence of surfaces in the lens system, and N d and V d are the indices of refraction and Abbe numbers, respectively, of the individual lens elements, said lens further having an aperture stop situated between said elements L8 and L9.