US4650291A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens
Assignee: Canon Inc
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Filing: 1983-08-10
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Granted: 1987-03-17
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Expires: 2003-08-10
Abstract
Abstract A zoom lens having, from front to rear, a zoom section having a plurality of lens groups movable for zooming, and an image forming section which is stationary during zooming, wherein a first lens group counting from the front in the zoom section is of positive refractive power, and a lens group F constituting part of the image forming section is made movable for focusing. A proper range of focal lengths of the aforesaid lens group F related with that of the image forming section is set forth to achieve good correction of aberrations.
Inventors
- 👤 Masatake Kato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:44
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/163; G02B15/143; G02B15/144
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
153 words
A zoom lens comprising: from front to rear, a zoom section having a plurality of lens groups which move during zooming, and an image forming section which is stationary during zooming, focusing being performed by moving a lens group F of negative refractive power constituting part of said image forming section, satisfying the following condition: 0.4<f.sub.F /f.sub.R <4 wherein f R denotes the focal length of said image forming section, and f F denotes the focal length of said lens group F, said zoom lens further comprising a meniscus-shaped lens of forward convexity which is stationary during focusing and arranged on the object side of said lens group F and a lens of positive refractive power which is stationary during focusing and arranged on the image side, whereby focusing from an infinitely distant object to an object at a short object distance is performed by moving said lens group F toward the rear.
Claim 2
Dependent Claim
153 words
A zoom lens comprising: from front to rear, a zoom section having a plurality of lens groups which move during zooming, and an image forming section which is stationary during zooming, focusing being performed by moving a lens group F of negative refractive power constituting part of said image forming section, satisfying the following condition: 0.4<f.sub.F /f.sub.R <4 wherein f R denotes the focal length of said image forming section, and f F denotes the focal length of said lens group F, said zoom lens further comprising a meniscus-shaped lens of forward convexity which is stationary during focusing and arranged on the object side of said lens group F and a lens of positive refractive power which is stationary during focusing and arranged on the image side, whereby focusing from an infinitely distant object to an object at a short object distance is performed by moving said lens group F toward the rear.
Claim 3
Dependent Claim
119 words
A zoom lens comprising: a frontmost lens unit movable for zooming and stationary during focusing; at least one movable lens unit movable simultaneously with, but independently from the frontmost lens unit, and an image forming lens section arranged at a position closer to the image than the movable lens unit and comprising a plurality of lens units; wherein the focusing is performed by moving one of said plurality of lens units of the image forming lens section, and in which the lens movable for focusing has a negative refractive power and satisfies the following condition: 0.4<|f.sub.F /f.sub.R |<4 in which f F represents the focal length and f R represents the focal length of the image forming lens section.
Claim 4
Dependent Claim
119 words
A zoom lens comprising: a frontmost lens unit movable for zooming and stationary during focusing; at least one movable lens unit movable simultaneously with, but independently from the frontmost lens unit, and an image forming lens section arranged at a position closer to the image than the movable lens unit and comprising a plurality of lens units; wherein the focusing is performed by moving one of said plurality of lens units of the image forming lens section, and in which the lens movable for focusing has a negative refractive power and satisfies the following condition: 0.4<|f.sub.F /f.sub.R |<4 in which f F represents the focal length and f R represents the focal length of the image forming lens section.
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) | 1990-03-16 | 1990-09-15 | 1991-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-16 | 1994-09-15 | 1995-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-16 | 1998-09-15 | 1999-03-17 | $7700.00 | Window Closed / Lapsed |