US4854680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom view finder
Assignee: Olympus Corp
•
Filing: 1988-03-10
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Granted: 1989-08-08
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Expires: 2008-03-10
Abstract
Abstract A zoom view finder comprising a plural number of lens units and so adapted as to perform zooming by displacing some of said lens units, said zoom view finder satisfying the following conditions: ##EQU1## wherein the reference symbol z represents zoom ratio of the lens system, the reference symbols ν max and ν min designate the maximum Abbe's number and the minimum Abbe's number respectively out of Abbe's numbers of said lens units, and the reference symbols P(Δγ) max and P(Δγ) min denotes the maximum and minimum values out of percentages of the chromatic aberrations of angular magnification relative to magnification levels.
Inventors
- 👤 Juro Kikuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:26
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/143; G02B15/1435; G02B15/143503; G02B23/00; G02B23/14; G02B23/145
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
179 words
A zoom finder comprising a first lens unit arranged on the extreme object side and having negative refractive power, a third lens unit arranged on the extreme image side and having negative refractive power, and a second lens unit arranged between said first and third lens unit and having positive lens units, for performing variation of focal length by shifting at least one of said lens units along the optical axis, and so designed as to satisfy the following conditions (1) and (2) ##EQU15## wherein the reference symbol z represents the zoom of said view finder, the reference symbol ν max designates the maximum Abbe's number out of Abbe's numbers of the lens units, the reference symbol ν min denotes the minimum Abbe's number out of Abbe's numbers of the lens units, the reference symbol P(Δγ) max represents the maximum value out of percentages of the chromatic aberrations of angular magnification relative to angular magnifications and the reference symbol P(Δγ) min designates the minimum value out of percentages of the chromatic aberrations of angular magnification relative to angular magnifications.
Claim 2
Dependent Claim
179 words
A zoom finder comprising a first lens unit arranged on the extreme object side and having negative refractive power, a third lens unit arranged on the extreme image side and having negative refractive power, and a second lens unit arranged between said first and third lens unit and having positive lens units, for performing variation of focal length by shifting at least one of said lens units along the optical axis, and so designed as to satisfy the following conditions (1) and (2) ##EQU15## wherein the reference symbol z represents the zoom of said view finder, the reference symbol ν max designates the maximum Abbe's number out of Abbe's numbers of the lens units, the reference symbol ν min denotes the minimum Abbe's number out of Abbe's numbers of the lens units, the reference symbol P(Δγ) max represents the maximum value out of percentages of the chromatic aberrations of angular magnification relative to angular magnifications and the reference symbol P(Δγ) min designates the minimum value out of percentages of the chromatic aberrations of angular magnification relative to angular magnifications.
Claim 3
Dependent Claim
76 words
A zoom finder according to claim 1 wherein said second lens unit has positive refractive power and consists of two lens components separated from each other by an airspace therebetween, said first and third lens units having negative refractive power are kept fixed during the variation of focal length, and said second lens unit having positive refractive power is shifted as a whole toward the object side for variation of focal length while varying said airspace.
Claim 4
Dependent Claim
13 words
A zoom view finder according to claim I satisfying the following condition: ##EQU16##
Claim 5
Dependent Claim
14 words
A zoom view finder according to claim 3 satisfying the following condition: ν.sub.min <60
Claim 6
Dependent Claim
39 words
A zoom view finder according to claim 2 wherein said first lens unit consists of a single negative lens, said second lens unit consists of two positive lenses and said third lens unit consists of a single negative lens.
Claim 7
Dependent Claim
37 words
A zoom view finder according to claim 2 wherein said first lens unit consists of two negative lenses, said second lens unit consists of two positive lenses and said third lens unit consists of a negative lens.
Claim 8
Dependent Claim
42 words
A zoom view finder according to the claim I wherein said first lens unit consists of two negative lenses, said second lens unit consists of a cemented doublet and a positive lens, and said third lens unit consists of a negative lens.
References Cited (Backward Citations)
US3051052A
Cited
US3454321A
Cited
US3788731A
Cited
US4018510A
Cited
US4094587A
Cited
JPS61167919A
Cited
JPS61213817A
Cited
US4725130A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-07 | 1993-02-06 | 1993-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-07 | 1997-02-06 | 1997-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-07 | 2001-02-06 | 2001-08-08 | $7700.00 | Window Closed / Lapsed |