Patent US3583791A successfully refreshed from Google Patents.
US3583791A
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US
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Retrofocus-type photographic lens
Assignee: Nikon Corp
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Filing: 1969-07-07
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Granted: 1971-06-08
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Expires: 1989-07-07
Abstract
Abstract This invention provides a retrofocus-type wide angle lens having a relative aperture of F/2.8, an angle of field of 75* and a back focus of more than 1.3 times the focal length and comprises seven lens elements, the first element is a negative meniscus lens convex to the object side, the second element is a negative meniscus lens convex to the object side, the third element is a biconvex positive lens, the fourth element is a positive meniscus lens concave to the object side, the fifth element is a biconcave negative lens and the sixth and seventh element are positive meniscus lenses concave to the object side, respectively.
Inventors
- 👤 Ikuo Mori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:08
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
219 words
An improved retrofocus-type photographic lens consisting of a diaphragm, a front group of spaced-apart lens elements positioned on the object side of said diaphragm and a rear group of spacedapart lens elements positioned on the image side of said diaphragm, the front group consisting of two negative meniscus lens elements with their concave surfaces facing the diaphragm and the rear group consisting of a biconcave lens element followed by two positive meniscus lens elements, wherein the convex surfaces of said two positive meniscus lens elements are on the image side of the diaphragm and wherein the improvement consists of a middle group of spaced-apart lens elements positioned on the object side of said diaphragm and consisting of a biconvex lens element followed by a positive meniscus lens element with its convex side facing the diaphragm and wherein the following relationships apply: R6 >R5 d6<d5 R7>R8wherein R5 and R6 are the radii of curvature of the first and second surfaces respectively of the biconvex lens element, wherein the axial thickness of the biconvex lens is d5, wherein the spacing between the biconvex lens and the positive meniscus lens immediately following it is d6, and wherein R7 and R8 are the radii of curvature of the first and second surfaces respectively of the positive meniscus lens immediately following the biconvex lens.
Claim 2
Dependent Claim
219 words
An improved retrofocus-type photographic lens consisting of a diaphragm, a front group of spaced-apart lens elements positioned on the object side of said diaphragm and a rear group of spacedapart lens elements positioned on the image side of said diaphragm, the front group consisting of two negative meniscus lens elements with their concave surfaces facing the diaphragm and the rear group consisting of a biconcave lens element followed by two positive meniscus lens elements, wherein the convex surfaces of said two positive meniscus lens elements are on the image side of the diaphragm and wherein the improvement consists of a middle group of spaced-apart lens elements positioned on the object side of said diaphragm and consisting of a biconvex lens element followed by a positive meniscus lens element with its convex side facing the diaphragm and wherein the following relationships apply: R6 >R5 d6<d5 R7>R8wherein R5 and R6 are the radii of curvature of the first and second surfaces respectively of the biconvex lens element, wherein the axial thickness of the biconvex lens is d5, wherein the spacing between the biconvex lens and the positive meniscus lens immediately following it is d6, and wherein R7 and R8 are the radii of curvature of the first and second surfaces respectively of the positive meniscus lens immediately following the biconvex lens.
Claim 3
Dependent Claim
26 words
A retrofocus-type photographic lens having numerical data substantially as set forth below: (relative aperture F/2.8, the angle of field 75* and the focal length f 100)
Claim 4
Dependent Claim
26 words
A retrofocus-type photographic lens having numerical data substantially as set forth below: (relative aperture F/2.8, the angle of field 75* and the focal length f 100)
Claim 5
Dependent Claim
26 words
A retrofocus-type photographic lens having numerical data substantially as set forth below: (relative aperture F/2.8, the angle of field 78*, and the focal length f 100)
Claim 6
Dependent Claim
26 words
A retrofocus-type photographic lens having numerical data substantially as set forth below: (relative aperture F/2.8, the angle of field 78*, and the focal length f 100)
References Cited (Backward Citations)
DE1250153B
Cited
FR1396907A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-07 | 1974-12-07 | 1975-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-07 | 1978-12-07 | 1979-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-07 | 1982-12-07 | 1983-06-08 | $7700.00 | Window Closed / Lapsed |