# US 5,703,726 A · Reverse telephoto lens > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,726 A - Document ID: US5703726A - Status: Granted - Kind: A - Application number: 08/631,500 - Filed: 1996-04-12 - Granted: 1997-12-30 - Earliest claimed: 1996-04-12 - Assignees: Eastman Kodak Company - Inventors: John D. Griffith - Web page: https://patentgrep.com/patent/US5703726A ## CPC - G02B 13/04: Reversed telephoto objectives - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A reverse telephoto lens includes a front negative group of lens components having a front component with greater than normal separation from a rear positive group of lens elements. Preferably, the front negative group also includes a rear positive component that is meniscus concave to the front. ## Claims ### Claim 1 A reverse telephoto lens comprising, in order from a front, object side of the lens to a rear, image side of the lens: a front negative group of lens components including a front negative component and a rear positive component, separated by a first airspace A1; a rear positive group of lens elements separated from the front negative group by a second airspace A2; said rear positive group of lens elements including at least two positive lens elements and a negative lens element located therebetween and a stop located in the second airspace, wherein the distance between the front negative component and the rear positive group is at least 2.5 times the focal length of the lens, and wherein A1.ltoreq.A2. ### Claim 2 (depends on 1) A reverse telephoto lens according to claim 1 wherein said distance is at least four times the focal length of the lens. ### Claim 3 (depends on 1) A reverse telephoto lens according to claim 1 wherein said distance is between four and five times the focal length of the lens. ### Claim 4 (depends on 1) A reverse telephoto lens according to claim 1 wherein the first airspace is between one and two times the focal length of the lens and is biconvex. ### Claim 5 (depends on 1) A reverse telephoto lens according to claim 1 wherein the second airspace is between 1.5 and three times the focal length of the lens. ### Claim 6 (depends on 1) A reverse telephoto lens according to claim 1 wherein the rear positive component is meniscus concave to the object. ### Claim 7 (depends on 1) A reverse telephoto lens according to claim 1 wherein the front negative component and the rear positive component are single elements and the first airspace is biconvex. ### Claim 8 (depends on 1) A lens according to claim 1, having the following numerical values: ______________________________________ efl = 6.83 F number = 2.84 Full field = 64.degree. Back focal length = 8.15 object distance = 2400 mm ______________________________________ R1 = -329.68 D1 = 1.50 N1 = 1.71300 V1 = 53.8 R2 = 9.26 D2 = 10.90 R3 = -116.45 D3 = 3.68 N3 = 1.71300 V3 = 53.8 R4 = -14.00 D4 = 10.24 R5 = 0.00 D5 = 1.75 R6 = 5.03 D6 = 2.60 N6 = 1.69350 V6 = 53.3 R7 = -4.23 D7 = 1.52 N7 = 1.78179 V7 = 37.1 R8 = 4.23 D8 = 0.60 R9 = 16.98 D9 = 1.86 N9 = 1.51680 V9 = 64.2 R10 = -6.36 D10 = 1.03 R11 = 0.00 D11 = 3.56 N11 = 1.54430 V11 = 70.2 R12 = 0.00 D12 = 3.00 R13 = 0.00 D13 = 0.76 N13 = 1.53338 V13 = 61.3 R14 = 0.00 D14 = 1.33 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.11 -R.sub.14 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 9 A reverse telephoto lens comprising, in order from the object side, a negative meniscus element with a convex side toward the object, a positive meniscus element with a concave side toward the object, the aperture stop, a positive biconvex element, a negative biconcave element, and a positive biconvex element, said lens system satisfying the following conditions: ##EQU7## where V.sub.i is the Abbe number of element i, efi.sub.i is the focal length of element i, efl is the focal length of the lens, X.sub.i is the bending of element i, d.sub.2 is the air space between the first and second element, d.sub.4 is the air space between the second element and the aperture stop, d.sub.5 is the air space between the aperture stop and the third element, and distances are in millimeters. ### Claim 10 (depends on 9) A lens according to claim 9 having the following numerical values, ______________________________________ efl = 6.84 F number = 2.84 Full field = 64.degree. Back focal length = 8.15 object distance = 2400 mm ______________________________________ R1 = 13.43 D1 = 1.75 N1 = 1.77250 V1 = 49.6 R2 = 6.49 D2 = 7.23 R3 = -12.19 D3 = 3.68 N3 = 1.58215 V3 = 42.1 R4 = -9.51 D4 = 10.06 R5 = 0.00 D5 = 1.75 R6 = 6.42 D6 = 2.60 N6 = 1.77250 V6 = 49.6 R7 = -10.05 D7 = 0.60 R8 = -5.89 D8 = 1.50 N8 = 1.72825 V8 = 28.4 R9 = 5.89 D9 = 0.70 R10 = 30.92 D10 = 1.86 N10 = 1.65113 V10 = 55.9 R11 = -6.56 D11 = 1.05 R12 = 0.00 D12 = 3.56 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 3.00 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 1.32 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 11 (depends on 9) A lens according to claim 9, having the following numerical values: ______________________________________ efl = 6.83 F number = 2.84 Full field = 64.degree. Back focal length = 8.15 object distance = 2400 mm ______________________________________ R1 = 15.54 D1 = 1.50 N1 = 1.72800 V1 = 50.6 R2 = 6.83 D2 = 10.29 R3 = -13.56 D3 = 3.68 N3 = 1.72800 V3 = 50.6 R4 = -10.18 D4 = 11.09 R5 = 0.00 D5 = 1.74 R6 = 5.75 D6 = 2.60 N6 = 1.72800 V6 = 50.6 R7 = -19.53 D7 = 0.57 R8 = -8.50 D8 = 1.50 N8 = 1.72595 V8 = 28.3 R9 = 5.02 D9 = 0.60 R10 = 16.14 D10 = 1.86 N10 = 1.64673 V10 = 55.5 R11 = -7.60 D11 = 1.05 R12 = 0.00 D12 = 3.56 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 3.00 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 1.32 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 12 A reverse telephoto lens comprising, in order from the object side, a negative meniscus element with convex side toward the object, a positive meniscus element with concave side toward the object, the aperture stop, a cemented doublet comprising a positive biconvex element and a negative biconcave element, and a positive biconvex element, said lens system satisfying the following conditions: 45.ltoreq.V.sub.1 .ltoreq.55 (1) 30.ltoreq.V.sub.2 .ltoreq.55 (2) 4.ltoreq. V.sub.3 .ltoreq.55 (3) 28.ltoreq.V.sub.4 .ltoreq.33 (4) 39.ltoreq.V.sub.5 .ltoreq.65 (5) where V.sub.i is the Abbe number of element i. ### Claim 13 A reverse telephoto lens comprising, in order from the object side, a negative element, a positive meniscus element with concave side toward the object, an aperture stop, a positive biconvex element having an aspheric rear surface with a sag ##EQU8## a negative biconcave element, and a positive element, where Y is the radius of the aspheric surface, k is the conic constant, and C is the curvature, and said lens system satisfying the following conditions: ##EQU9## where V.sub.i is the Abbe number of element i, efl.sub.i is the focal length of element i, efl is the focal length of the lens, X.sub.i is the bending of element i, d.sub.2 is the air space between the first and second element, d.sub.4 is the air space between the second element and the aperture stop, d.sub.5 is the air space between the aperture stop and the third element, k is the conic constant of the rear surface of the third element and all distances are in millimeters. ### Claim 14 (depends on 13) A lens according to claim 13 where the first element is negative meniscus with convex side toward the object and the fifth element is positive biconvex. ### Claim 15 (depends on 14) A lens according to claim 14 having the following numerical values: ______________________________________ efl = 5.36 F number 2.84 Full field = 59.degree. Back focal length = 7.99 object distance = 2400 mm ______________________________________ R1 = 31.76 D1 = 5.00 N1 = 1.69100 V1 = 54.7 R2 = 6.61 D2 = 5.65 R3 = -10.96 D3 = 4.00 N3 = 1.62004 V3 = 36.4 R4 = -8.99 D4 = 15.00 R5 = 0.00 D5 = 1.59 R6 = 6.91 D6 = 3.00 N6 = 1.72800 V6 = 50.6 C7 = -0.087589 D7 = 1.00 k7 = -3.447987 R8 = -6.33 D8 = 1.89 N8 = 1.78200 V8 = 26.0 R9 = 6.33 D9 = 0.84 R10 = 24.51 D10 = 2.35 N10 = 1.79980 V10 = 46.2 R11 = 6.51 D11 = 3.28 R12 = 0.00 D12 = 3.02 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 1.50 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 0.77 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 16 (depends on 13) A lens according to claim 13 where the first element is negative biconcave and the fifth element is positive biconvex. ### Claim 17 (depends on 16) A lens according to claim 16 having the following numerical values: ______________________________________ efl = 5.36 F number = 2.84 Full field = 59.5.degree. Back focal length = 8.10 object distance = 2400 mm ______________________________________ R1 = -100.00 D1 = 5.00 N1 = 1.69100 V1 = 54.7 R2 = 8.17 D2 = 3.99 R3 = -15.71 D3 = 4.00 N3 = 1.62004 V3 = 36.4 R4 = -9.41 D4 = 15.00 R5 = 0.00 D5 = 1.59 R6 = 7.03 D6 = 3.00 N6 = 1.72800 V6 = 50.6 c7 = -0.093853 D7 = 1.00 k7 = -1.692032 R8 = -6.15 D8 = 1.89 N8 = 1.78200 V8 = 26.0 R9 = 6.15 D9 = 0.84 R10 = 27.13 D10 = 2.35 N10 = 1.79980 V10 = 46.2 R11 = -6.25 D11 = 3.28 R12 = 0.00 D12 = 3.02 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 1.50 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 0.87 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 18 (depends on 13) A lens according to claim 13 where the first element is negative meniscus with convex side toward the object and the fifth element is positive meniscus with concave side toward the object. ### Claim 19 (depends on 18) A lens according to claim 18 having the following numerical values: ______________________________________ efl = 5.37 F number = 2.84 Full field = 58.6.degree. Back focal length = 8.01 object distance = 2400 mm ______________________________________ R1 = 16.05 D1 = 5.00 N1 = 1.69100 V1 = 54.7 R2 = 5.80 D2 = 5.65 R3 = -8.20 D3 = 4.00 N3 = 1.62004 V3 = 36.4 R4 = -8.09 D4 = 15.00 R5 = 0.00 D5 = 1.59 R6 = 8.09 D6 = 3.00 N6 = 1.72800 V6 = 50.6 c7 = -0.106097 D7 = 1.00 k7 = -6.680424 R8 = -6.82 D8 = 1.89 N8 = 1.78200 V8 = 26.0 R9 = 6.82 D9 = 0.84 R10 = -96.45 D10 = 2.35 N10 = 1.79980 V10 = 46.2 R11 = -5.10 D11 = 3.28 R12 = 0.00 D12 = 3.02 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 1.50 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 0.78 ______________________________________ said lens being followed by a birefringent blur filter and army photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 20 A reverse telephoto lens comprising, in order from the object side, a negative meniscus element with convex side towards the object, a positive meniscus element with concave side toward the stop, the aperture stop, a positive biconvex element having an aspheric rear surface with a sag ##EQU10## a negative biconcave element, and a positive biconvex element, where Y is the radius, k is the conic constant, and C is the curvature of the aspheric surface, and the lens having the following numerical values: ______________________________________ efl = 5.40 F number = 2.84 Full field = 58.8.degree. Back focal length = 6.29 object distance = 2400 mm ______________________________________ R1 = 18.73 D1 = 1.50 N1 = 1.51680 V1 = 64.2 R2 = 5.29 D2 = 3.72 R3 = -8.77 D3 = 4.00 N3 = 1.69680 V3 = 55.5 R4 = -8.50 D4 = 11.85 R5 = 0.00 D5 = 1.55 R6 = 6.25 D6 = 3.00 N6 = 1.72800 V6 = 50.6 c7 = -0.107813 D7 = 1.00 k7 = -5.385944 R8 = -5.94 D8 = 1.76 N8 = 1.80518 V8 = 25.4 R9 = 5.94 D9 = 0.85 R10 = 19.70 D10 = 1.93 N10 = 1.77250 V10 = 49.6 R11 = -6.20 D11 = 1.61 R12 = 0.00 D12 = 3.02 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 1.50 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 0.74 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant. ### Claim 21 A reverse telephoto lens comprising, in order from the object side, a negative meniscus element with convex side towards the object, a positive meniscus element with concave side toward the stop, the aperture stop, a positive biconvex element, a negative biconcave element, and a positive biconvex element, the lens having the following numerical values: ______________________________________ efl = 5.40 F number = 2.84 Full field = 60.degree. Back focal length = 6.28 object distance = 2400 mm ______________________________________ R1 = 91.28 D1 = 1.50 N1 = 1.56384 V1 = 60.8 R2 = 4.70 D2 = 4.20 R3 = -22.94 D3 = 4.00 N3 = 1.69680 V3 = 55.5 R4 = -7.68 D4 = 6.77 R5 = 0.00 D5 = 2.72 R6 = 6.62 D6 = 2.05 N6 = 1.69680 V6 = 55.5 R7 = -35.09 D7 = 0.75 R8 =-20.53 D8 = 1.50 N8 = 1.80518 V8 = 25.4 R9 = 4.41 D9 = 0.74 R10 = 7.92 D10 = 2.00 N10 = 1.77250 V10 = 49.6 R11 = -7.92 D11 = 1.56 R12 = 0.00 D12 = 3.02 N12 = 1.54430 V12 = 70.2 R13 = 0.00 D13 = 1.50 R14 = 0.00 D14 = 0.76 N14 = 1.53338 V14 = 61.3 R15 = 0.00 D15 = 0.78 ______________________________________ said lens being followed by a birefringent blur filter and array photodetector cover glass, as indicated by R.sub.12 -R.sub.15 in the table, and being focusable by adjusting D5 and D11 such that their sum is constant.