US3868174A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephoto type objective of large relative aperture ratio
Assignee: Canon Inc
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Filing: 1973-07-24
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Granted: 1975-02-25
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Expires: 1993-07-24
Abstract
Abstract A telephoto type objective having a large relative aperture ratio comprising a three-component positive front lens group and a two-component negative rear lens group, which is spherically and chromatically corrected and which also is corrected for coma and astigmatism, to thereby provide high grade imaging performance over the entire field of the picture frame, particularly regarding reduced secondary color.
Inventors
- 👤 Hideo Yakota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:01
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
84 words
A telephoto type objective lens, having a large relative aperture ratio, comprising a front lens group of positive refractive power and a rear lens group of negative refractive power; said front lens group including, in sequence from front to rear and in spaced relation to each other, a biconvex single lens, a biconcave single lens and a positive single lens; said biconvex single lens being a fluorspar; said rear lens group including in sequence and in alternation a negative lens and a positive lens.
Claim 2
Dependent Claim
84 words
A telephoto type objective lens, having a large relative aperture ratio, comprising a front lens group of positive refractive power and a rear lens group of negative refractive power; said front lens group including, in sequence from front to rear and in spaced relation to each other, a biconvex single lens, a biconcave single lens and a positive single lens; said biconvex single lens being a fluorspar; said rear lens group including in sequence and in alternation a negative lens and a positive lens.
Claim 3
Dependent Claim
50 words
A telephoto type objective lens having a large relative aperture ratio, as claimed in claim 1, in which said positive single lens of said front lens group is a biconvex lens; said rear lens group including a negative singlet and a positive singlet cemented together with a forwardly facing concavity.
Claim 4
Dependent Claim
26 words
A telephoto type objective lens having a large relative aperture ratio, as claimed in claim 2, in which said objective lens satisfies the following constructional data:
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) | 1978-02-24 | 1978-08-26 | 1979-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-24 | 1982-08-26 | 1983-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-24 | 1986-08-26 | 1987-02-25 | $7700.00 | Window Closed / Lapsed |