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US3848969A Expired / Lapsed US ⏱️ 0.0 years remaining

A short physical length zoom lens

Assignee: Canon Inc
•
Filing: 1973-04-05
•
Granted: 1974-11-19
•
Expires: 1993-04-05
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Abstract

Abstract A zoom lens system consisting of, in the order of the entrant light beam, a front movable lens group having a negative focal length and a rear movable lens group having a positive focal length which are mechanically moved, said front lens group comprising, in combination, at least two positive lens members and negative lens members, said rear lens group comprising positive and negative lens members of which the positive lens member nearest to the object comprises at least two positive lens elements, and said zoom lens system satisfying certain conditions related to one another among the focal length F1 of the front lens group, the air space lw between the front and rear lens groups positioned at the shortest focal length range of the entire lens system, the focal length f2 of the rear lens group, the focal length f3 of a refractive surface of the negative lens member in the rear lens group, said surface facing the image plane and having a strong negative power, and the focal length f4 of the rearmost positive lens member.

Inventors

  • 👤 A Tajima

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 22:05
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/177

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 136 words
A short physical length optical objective of the zoom type comprising, in the direction of an incident light beam, a front lens group of negative power and a rear lens group of positive power axially separated from each other by a variable air space to effect magnification variation, said front group including, in succession in said direction, a negative meniscus lens element having a convex forward surface, a positive lens element having a strongly convex rear surface, a double concave lens element, and two positive meniscus lens elements each having a convex forward surface, said rear lens group comprising a plurality of mutually spaced lenses including, in succession in said direction, two positive meniscus lens elements each having a convex forward surface, a negative lens element having a concave rear surface, and a positive lens element.
Claim 2
Dependent Claim 136 words
A short physical length optical objective of the zoom type comprising, in the direction of an incident light beam, a front lens group of negative power and a rear lens group of positive power axially separated from each other by a variable air space to effect magnification variation, said front group including, in succession in said direction, a negative meniscus lens element having a convex forward surface, a positive lens element having a strongly convex rear surface, a double concave lens element, and two positive meniscus lens elements each having a convex forward surface, said rear lens group comprising a plurality of mutually spaced lenses including, in succession in said direction, two positive meniscus lens elements each having a convex forward surface, a negative lens element having a concave rear surface, and a positive lens element.
Claim 3
Dependent Claim 27 words
The objective as defined in claim 1, in which the characteristics of the lenses of the front and rear lens groups are defined by the following tables:
Claim 4
Dependent Claim 34 words
An objective as defined in claim 1, in which said double lens element and the next succeeding position meniscus lens element in the front group are cemented together to form a doublet lens member.
Claim 5
Dependent Claim 27 words
An objective as defined in claim 3, in which the characteristics of the lenses of the front and rear lens groups are defined by The following tables:

References Cited (Backward Citations)

US3143590A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1977-11-18 1978-05-20 1978-11-19 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1981-11-18 1982-05-20 1982-11-19 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1985-11-18 1986-05-20 1986-11-19 $7700.00 Window Closed / Lapsed

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