Patent US4099845A successfully refreshed from Google Patents.
US4099845A
Expired / Lapsed
US
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Zoom lens with aberration variation prevented for focusing
Assignee: Canon Inc
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Filing: 1976-12-01
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Granted: 1978-07-11
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Expires: 1996-12-01
Abstract
Abstract A focusing part in a wide-angle zoom lens. The focusing section of a wide angle zoom lens is composed, from the object end, of a diverging fixed lens group, a converging movable lens group and a converging fixed lens group. The movable lens group remains stationary during a zooming operation and moves along its optical axis toward an image when focusing from a distant object onto a nearer object. Aberrations remain unvaried even when focusing onto a nearby object. The converging fixed group furnishes a suitably positioned object point for a zooming section arranged behind the focusing section. The converging fixed lens group is composed of a plurality of lenses contributing to improvement in the image quality.
Inventors
- 👤 Kunio Takesi
- 👤 Kazuo Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:22
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/143; G02B15/1431
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
149 words
A zoom lens capable of preventing aberration variation for focusing which comprises: a front lens part which consists of, from the object side, a first fixed lens group, a movable lens group and a second fixed lens group and which possesses a positive refractive power irrespective of the position of the movable lens group, the first fixed lens group having a negative refractive power while both the movable lens group and the second fixed lens group having positive refractive powers; for re-focusing from a distant object onto a near object, the movable lens group moves in the direction of an image of the object; a zooming lens part which is provided with at least two movable lens groups, the zooming lens part being disposed on the image side of said front lens part; and an image forming lens group disposed on the image side of said zooming lens part.
Claim 2
Dependent Claim
149 words
A zoom lens capable of preventing aberration variation for focusing which comprises: a front lens part which consists of, from the object side, a first fixed lens group, a movable lens group and a second fixed lens group and which possesses a positive refractive power irrespective of the position of the movable lens group, the first fixed lens group having a negative refractive power while both the movable lens group and the second fixed lens group having positive refractive powers; for re-focusing from a distant object onto a near object, the movable lens group moves in the direction of an image of the object; a zooming lens part which is provided with at least two movable lens groups, the zooming lens part being disposed on the image side of said front lens part; and an image forming lens group disposed on the image side of said zooming lens part.
Claim 3
Dependent Claim
25 words
A zoom lens according to claim 1, wherein said movable lens group includes a positive meniscus lens disposed with its concave face facing the object.
Claim 4
Dependent Claim
113 words
A zoom lens according to claim 1, wherein said first fixed lens group consists of a negative meniscus lens the convex face of which is disposed to face the object, a bi-concave lens and a positive meniscus lens the convex face of which is disposed to face the object; said movable lens group consists of a positive meniscus lens the concave face of which is disposed to face the object; and said second fixed lens group consists of a negative meniscus lens the convex face of which is disposed to face the object, a positive meniscus lens the convex face of which is also disposed to face the object and a bi-convex lens.
Claim 5
Dependent Claim
28 words
A zoom lens as in claim 1, wherein said movable lens group of the front lens part has a magnifying power at any position within its movable range.
References Cited (Backward Citations)
US3598476A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |