US3856385A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide-angle lens assembly of retrofocus type
Assignee: Pentax Corp
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Filing: 1973-04-25
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Granted: 1974-12-24
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Expires: 1993-04-25
Abstract
Abstract A wide-angle retrofocus type of objective composed of eight lenses, wherein the third and fourth lenses are cemented together, the objective having a back focus which is at least 1.25 times the focal distance of the entire objective. The front lens is of a relatively small diameter while the parameters of the various lenses are chosen in such a way that an exceedingly effective performance is achieved with aberrations being reduced to a minimum with the group of lenses situated in front of the diaphragm prolonging the back focus while reducing the incident angle on the following group, without undesirably increasing the Petzval sum.
Inventors
- 👤 Y Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:44
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
44 words
In a wide-angle retrofocus type of objective having eight lenses I-VIII wherein lenses III and IV are cemented together and have a common surface whose radius of curvature is r6, said objective having for a focal length F of 100 mm, the following data:
Claim 2
Dependent Claim
44 words
In a wide-angle retrofocus type of objective having eight lenses I-VIII wherein lenses III and IV are cemented together and have a common surface whose radius of curvature is r6, said objective having for a focal length F of 100 mm, the following 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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |