Patent US3661445A successfully refreshed from Google Patents.
US3661445A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens system
Assignee: Canon Inc
•
Filing: 1970-06-29
•
Granted: 1972-05-09
•
Expires: 1990-06-29
Abstract
Abstract The zoom lens system of this invention is capable of extreme close-up photography, and consists mainly of a focusing lens group having positive refractive power and a negative refractive power variator. The variator is divided into a positive refractive power lens group and a negative refractive power lens group. In phototaking from the infinity to a normal distance, said focusing lens group is shifted for focusing and for focusing a subject located closer than said normal distance, the variator is held in telephoto position and then the positive refractive power lens group of the variator is shifted forward for focusing.
Inventors
- 👤 Atsushi Someya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:07
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/22
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
141 words
In a zoom lens system, a focusing lens component having a positive refractive power, a variator lens component having a negative refractive power, a compensator lens component for compensating focal point position, and a relay lens component, said variator lens component comprising a positive refractive power lens and a negative refractive power lens, the focusing lens component being shiftable toward an object to be photographed and the positive refractive power lens and the negative refractive power lens of the variator lens component being shiftable as a unit toward the object, while the distance between the positive and the negative lenses remains unchanged to provide focusing from infinity to a normal phototaking distance and said positive lens of the variator lens component being shiftable by itself further toward the object for focusing from said normal phototaking distance to an extreme close-up distance.
Claim 2
Dependent Claim
141 words
In a zoom lens system, a focusing lens component having a positive refractive power, a variator lens component having a negative refractive power, a compensator lens component for compensating focal point position, and a relay lens component, said variator lens component comprising a positive refractive power lens and a negative refractive power lens, the focusing lens component being shiftable toward an object to be photographed and the positive refractive power lens and the negative refractive power lens of the variator lens component being shiftable as a unit toward the object, while the distance between the positive and the negative lenses remains unchanged to provide focusing from infinity to a normal phototaking distance and said positive lens of the variator lens component being shiftable by itself further toward the object for focusing from said normal phototaking distance to an extreme close-up distance.
Claim 3
Dependent Claim
111 words
A zoom lens system according to claim 1, wherein there is maintained the following relationships: S1, S2 and S3 and S1'', S2'' and S3'' being the distances between the objects and images formed by the focusing lens (L1), the positive refractive power lens (L2) and the negative refractive power lens (L3), respectively, e being the distance between the principal points of the lens groups L2 and L3, l being the distance between the principal points of the lens groups L1 and L3, f1, f2 and f3 being the focal lengths of the lenses L1 L2 and L3, respectively, and M being the magnification obtained by the lenses L1, L2 and L3.
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) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |