US4991945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens
Assignee: Eastman Kodak Co
•
Filing: 1989-07-05
•
Granted: 1991-02-12
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Expires: 2009-07-05
Abstract
Abstract A zoomable telephoto lens, comprising only five elements. The first three elements form a positive group and the last two elements form a negative group. The airspace between the two groups is made variable to effect zooming.
Inventors
- 👤 Lee R. Estelle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:57
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/142; G02B15/1425
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
84 words
A lens system capable of operation in wide angle and telephoto modes, including five lens elements arranged in two groups, an airspace between said groups, the length of said airspace being variable for zooming, three of said optical elements being positive and two of the said optical elements being negative, said optical elements having weak spherical surfaces or weak bendings so as to fulfill the following condition: ##EQU2## where R i =radii of curvature N=number of surfaces Clap i =clear aperture of surface i.
Claim 2
Dependent Claim
84 words
A lens system capable of operation in wide angle and telephoto modes, including five lens elements arranged in two groups, an airspace between said groups, the length of said airspace being variable for zooming, three of said optical elements being positive and two of the said optical elements being negative, said optical elements having weak spherical surfaces or weak bendings so as to fulfill the following condition: ##EQU2## where R i =radii of curvature N=number of surfaces Clap i =clear aperture of surface i.
Claim 3
Dependent Claim
35 words
A lens system as in claim 1, wherein said positive group is in front of said negative group, said negative group having a last lens element, said last lens element having a concave rear surface.
Claim 4
Dependent Claim
42 words
A lens system as in claim 2, wherein said negative, second group consists of two optical elements, one of the two optical elements of said second group being a positive element and the other of said two elements being a negative element.
Claim 5
Dependent Claim
29 words
A lens system as in claim 2, wherein the said positive lens element of said negative group is in front of said negative lens element of said negative group.
Claim 6
Dependent Claim
31 words
A lens system as in claim 2, 3 or 4, wherein said first, positive group has one positive lens element on each of the two sides of the negative lens element.
Claim 7
Dependent Claim
62 words
A lens system that satisfies the following conditions: ______________________________________
Refraction
Index Abbe No.
Surface Radius Thickness Nd Vd
______________________________________
1 25.8307 3.250 1.697 55.5
2 135.092 2.110
3 -37.6293 5.100 1.805 25.4
4 2331.60 5.900
Diaphragm 2.855
5 24.1911 3.120 1.697 55.5
6 -48.6420 A variable
7 -73.0033 4.450 1.697 55.5
8 -20.9629 2.855
9 -12.4750 2.000 1.786 44.2
10 2572.28
______________________________________
Claim 8
Dependent Claim
62 words
A lens system that satisfies the following conditions: ______________________________________
Refraction
Index Abbe No.
Surface Radius Thickness Nd Vd
______________________________________
1 25.8307 3.250 1.697 55.5
2 135.092 2.110
3 -37.6293 5.100 1.805 25.4
4 2331.60 5.900
Diaphragm 2.855
5 24.1911 3.120 1.697 55.5
6 -48.6420 A variable
7 -73.0033 4.450 1.697 55.5
8 -20.9629 2.855
9 -12.4750 2.000 1.786 44.2
10 2572.28
______________________________________
References Cited (Backward Citations)
FR1259007A
Cited
JPS5391756A
Cited
US4682860A
Cited
US4815830A
Cited
US4772106A
Cited
US4911539A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |