US3748022A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reverse telephoto type lens prevented from the deterioration of image at the time of close shot
Assignee: Canon Inc
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Filing: 1972-03-03
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Granted: 1973-07-24
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Expires: 1992-03-03
Abstract
Abstract A reverse telephoto type lens adapted for preventing the deterioration of image at the time of close shot, comprising a front lens group having negative refractive power and a back lens group having positive refractive power, wherein the latter lens group is further divided into two positive lens groups, which are spaced by a variable air interval, and whole lens system may be shifted approximately in proportion to the variation of said interval.
Inventors
- 👤 A Tajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:52
CPC Classifications
G; G02; G02B; G02B13/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
309 words
A reverse telephoto lens, comprising a front lens group I having a negative refractive power and a back lens group II having a positive refractive power, said lens group II being divided into two positive lens groups II 1 and II 2 spaced from each other by an air interval, said air interval being variable, said two groups together being shiftable along the axis, the distance between the lens groups II1 and II2 being variable during shift of said groups so as to change the air interval approximately in proportion to the amount of shift so as to prevent deterioration of the image, said groups having a plurality of individual lenses, the following conditions being satisfied for the lenses: R1 -5.776 d1 0.0975 R2 -3.231 d2 0.0028 N1 1.697 V1 48.5 R3 1.816 d3 0.0418 R4 0.4944 d4 0.3462 N2 1.51633 V2 64.0 R5 -0.9749 d5 0.0972 R6 -1.082 d6 0.0029 N2 1.70154 V3 41.1 R7 1.072 d7 0.0960 R8 15.83 d8 0.0419 N4 1.7 V4 48.0 R9 1.333 d9 0.2890 R10 124.1 d10 variable* Variable air interval D10 is 0.1541 at the object distance of infinity and is 0.1345 at the time of close shot with a magnification of 0.118 N5 1.7737 V5 49.2 R11 -3.877 d11 0.0279 R12 0.8554 d12 0.0905 N6 1.76182 V6 26.5 R13 -1.170 d13 0.028 R14 13.96 d14 0.1226 N7 1.80518 V7 25.4 R15 -0.6989 d15 0.0029 N8 1.7737 V8 49.2 R16 1.970 d16 0.0827 N9 1.8061 V9 40.8 R17 -3.278 f 1 1 : 2 2 omega 64* back focus 1.1066 wherein, R : radius of curvature of each refraction surface, in order of numerals. d : thickness of each lens on axis or air interval, in order of numerals. N : refractive index of each lens, in order of numerals. V : Abbe''s number of each lens, in order of numerals.
Claim 2
Dependent Claim
309 words
A reverse telephoto lens, comprising a front lens group I having a negative refractive power and a back lens group II having a positive refractive power, said lens group II being divided into two positive lens groups II 1 and II 2 spaced from each other by an air interval, said air interval being variable, said two groups together being shiftable along the axis, the distance between the lens groups II1 and II2 being variable during shift of said groups so as to change the air interval approximately in proportion to the amount of shift so as to prevent deterioration of the image, said groups having a plurality of individual lenses, the following conditions being satisfied for the lenses: R1 -5.776 d1 0.0975 R2 -3.231 d2 0.0028 N1 1.697 V1 48.5 R3 1.816 d3 0.0418 R4 0.4944 d4 0.3462 N2 1.51633 V2 64.0 R5 -0.9749 d5 0.0972 R6 -1.082 d6 0.0029 N2 1.70154 V3 41.1 R7 1.072 d7 0.0960 R8 15.83 d8 0.0419 N4 1.7 V4 48.0 R9 1.333 d9 0.2890 R10 124.1 d10 variable* Variable air interval D10 is 0.1541 at the object distance of infinity and is 0.1345 at the time of close shot with a magnification of 0.118 N5 1.7737 V5 49.2 R11 -3.877 d11 0.0279 R12 0.8554 d12 0.0905 N6 1.76182 V6 26.5 R13 -1.170 d13 0.028 R14 13.96 d14 0.1226 N7 1.80518 V7 25.4 R15 -0.6989 d15 0.0029 N8 1.7737 V8 49.2 R16 1.970 d16 0.0827 N9 1.8061 V9 40.8 R17 -3.278 f 1 1 : 2 2 omega 64* back focus 1.1066 wherein, R : radius of curvature of each refraction surface, in order of numerals. d : thickness of each lens on axis or air interval, in order of numerals. N : refractive index of each lens, in order of numerals. V : Abbe''s number of each lens, in order of numerals.
Claim 3
Dependent Claim
34 words
A lens as in claim 1, wherein the groups are shifted forward for close-up shots and the air interval is changed approximately in proportion to the amount of forward shift for a close-up shot.
Claim 4
Dependent Claim
134 words
A lens system, comprising front lens means having a negative refractive power, back lens means having a positive refractive power, said front lens means and said back lens means togther forming an inverted telephoto type lens, said back lens means having two positive lens groups spaced from each other by an air interval, said lens groups being movable relative to each other so as to vary the air interval, said first lens means and said second lens means being shiftable along the axis for focusing, said groups being movable relative to each other so as to change the interval approximately in proportion to the shift of said first and second lens means for at least a portion of the movement range of said lens means and thereby prevent deterioration of an image being formed.
Claim 5
Dependent Claim
134 words
A lens system, comprising front lens means having a negative refractive power, back lens means having a positive refractive power, said front lens means and said back lens means togther forming an inverted telephoto type lens, said back lens means having two positive lens groups spaced from each other by an air interval, said lens groups being movable relative to each other so as to vary the air interval, said first lens means and said second lens means being shiftable along the axis for focusing, said groups being movable relative to each other so as to change the interval approximately in proportion to the shift of said first and second lens means for at least a portion of the movement range of said lens means and thereby prevent deterioration of an image being formed.
Claim 6
Dependent Claim
56 words
A system as in claim 3, wherein said first and second lens means may be moved forward together for focusing on a close-up object, said groups being movable relative to each other so as to change the air interval proportional to the shift of said lens means in the range of focusing for a close-up shot.
Claim 7
Dependent Claim
37 words
A lens system as in claim 3, wherein said front lens means has a forward element, said forward element having a forward surface facing an object whose image is to be formed, said forward surface being concave.
Claim 8
Dependent Claim
56 words
A system as in claim 5, wherein said first and second lens means may be moved forward together for focusing on a close-up object, said groups being movable relative to each other so as to change the air interval proportional to the shift of said lens means in the range of focusing for a close-up shot.
Claim 9
Dependent Claim
84 words
A system as in claim 3, wherein said first and second lens means satisfy a condition 0.35< phi 1+ phi 2-D1 phi 1 phi 2<1.0 when the refractive power of said front lens means and said back lens means together are 1 and the refractive power of the front lens means is phi 1, the refractive power of said back lens means is 1002, and the interval between the principal point of said front lens means and 1 of said lens groups is D.
Claim 10
Dependent Claim
45 words
A lens system as in claim 3, wherein when the magnification of the front lens means and the back lens means together is less than 0.2 the corrected air interval is less than 5 percent of the focal distance of said inverted telephoto lens together.
Claim 11
Dependent Claim
84 words
A system as in claim 8, wherein said first and second lens means satisfy a condition 0.35< phi 1+ phi 2-D1 phi 1 phi 2<1.0 the refractive power of said front lens means and said back lens means together are 1 and lthe refractive power of the front lens means is phi 1, the refractive power of said back lens means being phi 2, and the interval between the principal point of said front lens means and 1 of said lens groups is D.
Claim 12
Dependent Claim
85 words
A system as in claim 3, wherein said first and second lens means satisfy a condition, 0.35< phi 1+ phi 2-D phi 1 phi 2<1.0 when the refractive power of said front lens means and said back lens means together are 1 and the refractive power of the front lens means is phi 1, the refractive power of said back lens means being phi 2, and the interval between the principal point of said front lens means and 1 of said lens groups is D.
Claim 13
Dependent Claim
44 words
A system as in claim 10, wherein when the magnification of the front lens means and the back lens means together is less than 0.2 the corrected air interval is less than 5 percent of the focal distance of said inverted telephoto lens together.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |