US5227920A
Expired / Lapsed
US
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Zoom lens
Assignee: Nikon Corp
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Filing: 1992-10-27
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Granted: 1993-07-13
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Expires: 2012-10-27
Abstract
Abstract A compact zoom lens, which can attain a compact lens system while maintaining a simple lens arrangement including six lenses, and can minimize deterioration of performance caused by a variation upon assembling, is disclosed. The compact zoom lens includes a positive first lens group G 1 and a negative second lens group G 2 . The first lens group G 1 has, in turn from the object side, a positive meniscus lens component L 1 with the convex surface facing the object side, a meniscus-shape junction negative lens component L 2 constituted by a double-concave negative lens component L 2n and a double-convex positive lens component L 2p , and a double-convex positive lens component L 3 . The second lens group G 2 has, in turn from the object side, a positive meniscus lens component L 4 with the convex surface facing the image side, and a negative meniscus lens component L 5 with the convex surface facing the image side, and at least one lens surface of the second lens group G 2 is formed to have an aspherical surface shape. The zoom lens satisfies six conditions.
Inventors
- 👤 Atsushi Shibayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:56
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/18; G02B15/00; G02B15/14; G02B15/142; G02B15/1421
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
374 words
A zoom lens, which includes a first lens group G 1 having a positive refracting power and a second lens group G 2 having a negative refracting power, and performs a zooming operation from a wide-angle end to a telephoto end by decreasing a space between said first and second lens groups G 1 and G 2 , wherein said first lens group G 1 has, in order from an object side, a positive meniscus lens component L 1 with a convex surface facing the object side, a cemented negative lens component L 2 constituted by a double-concave negative lens component L 2n and a double-convex positive lens component L 2p , and having a meniscus shape as a whole, and a double-convex positive lens component L 3 , said second lens group G 2 has, in order from the object side, a positive meniscus lens component L 4 with a convex surface facing an image side, and a negative meniscus lens component L 5 with a convex surface facing the image side, and said zoom lens is arranged to satisfy the following conditions: 0.09<dL.sub.2 /f.sub.W <0.18 0.45<(nL.sub.2n -nL.sub.2p)·f.sub.W /r.sub.4 <0.9 -4<fL.sub.2 /f.sub.1 <-1.8 1.1<fL.sub.3 /f.sub.1 <1.6 where f W : the focal length of the entire system at the wide-angle end dL 2 : the axial lens thickness of said cemented negative lens component L 2 in said first lens group G 1 nL 2n : the refractive index of said double-concave negative lens component L 2n forming said cemented negative lens component L 2 in said first lens group G 1 nL 2p : the refractive index of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 r 4 : the radius of curvature of the junction surface in said cemented negative lens component L 2 in said first lens group G 1 fL 2 : the focal length of said cemented negative lens component L 2 in said first lens group G 1 fL 3 : the focal length of said double-convex positive lens component L 3 in said first lens group G 1 f 1 : the focal length of said first lens group G 1 .
Claim 2
Dependent Claim
374 words
A zoom lens, which includes a first lens group G 1 having a positive refracting power and a second lens group G 2 having a negative refracting power, and performs a zooming operation from a wide-angle end to a telephoto end by decreasing a space between said first and second lens groups G 1 and G 2 , wherein said first lens group G 1 has, in order from an object side, a positive meniscus lens component L 1 with a convex surface facing the object side, a cemented negative lens component L 2 constituted by a double-concave negative lens component L 2n and a double-convex positive lens component L 2p , and having a meniscus shape as a whole, and a double-convex positive lens component L 3 , said second lens group G 2 has, in order from the object side, a positive meniscus lens component L 4 with a convex surface facing an image side, and a negative meniscus lens component L 5 with a convex surface facing the image side, and said zoom lens is arranged to satisfy the following conditions: 0.09<dL.sub.2 /f.sub.W <0.18 0.45<(nL.sub.2n -nL.sub.2p)·f.sub.W /r.sub.4 <0.9 -4<fL.sub.2 /f.sub.1 <-1.8 1.1<fL.sub.3 /f.sub.1 <1.6 where f W : the focal length of the entire system at the wide-angle end dL 2 : the axial lens thickness of said cemented negative lens component L 2 in said first lens group G 1 nL 2n : the refractive index of said double-concave negative lens component L 2n forming said cemented negative lens component L 2 in said first lens group G 1 nL 2p : the refractive index of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 r 4 : the radius of curvature of the junction surface in said cemented negative lens component L 2 in said first lens group G 1 fL 2 : the focal length of said cemented negative lens component L 2 in said first lens group G 1 fL 3 : the focal length of said double-convex positive lens component L 3 in said first lens group G 1 f 1 : the focal length of said first lens group G 1 .
Claim 3
Dependent Claim
86 words
A zoom lens according to claim 1, wherein said zoom lens is arranged to satisfy the following conditions: 0.5<Σd.sub.W /f.sub.W <0.85 2<fL.sub.1 ·L.sub.2 /f.sub.1 <9 where Σd W : the axial lens thickness from the most object-side lens surface to the most image-side lens surface of said zoom lens at the wide-angle end fL 1 ·L 2 : the composite focal length of said positive meniscus lens component L 1 and said cemented negative lens component L 2 in said first lens group G 1 .
Claim 4
Dependent Claim
28 words
A zoom lens according to claim 2, wherein at least one lens surface in said second lens group G 2 is formed to have an aspherical surface shape.
Claim 5
Dependent Claim
81 words
A zoom lens according to claim 3, wherein said zoom lens is arranged to satisfy the following condition: 17<νL.sub.2p -νL.sub.2n <30 where νL 2p : the Abbe's number of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 νL 2n : the Abbe's number of said double-concave negative lens component L 2n forming said cemented negative lens component L 2 in said first lens group G 1 .
Claim 6
Dependent Claim
42 words
A zoom lens according to claim 3, wherein the aspherical surface shape in said second lens group G 2 is formed so that a positive refracting power is gradually increased from the optical axis toward a peripheral portion on the aspherical surface.
Claim 7
Dependent Claim
81 words
A zoom lens according to claim 5, wherein said zoom lens is arranged to satisfy the following condition: 17<νL.sub.2p -νL.sub.2n <30 where νL 2p : the Abbe's number of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 νL 2n : the Abbe's number of said double-concave negative lens component L 2n forming said cemented negative lens component L 2 in said first lens group G 1 .
Claim 8
Dependent Claim
42 words
A zoom lens according to claim 3, wherein the aspherical surface shape in said second lens group G 2 is formed so that a negative refracting power is gradually decreased from the optical axis toward a peripheral portion on the aspherical surface.
Claim 9
Dependent Claim
81 words
A zoom lens according to claim 7, wherein said zoom lens is arranged to satisfy the following condition: 17<νL.sub.2p -νL.sub.2n <30 where νL 2p : the Abbe's number of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 νL 2n : the Abbe's number of said double-concave negative lens component L 2n forming said cemtend negative lens component L 2 in said first lens group G 1 .
Claim 10
Dependent Claim
28 words
A zoom lens according to claim 1, wherein at least one lens surface in said second lens group G 2 is formed to have an aspherical surface shape.
Claim 11
Dependent Claim
79 words
A zoom lens according to claim 9, wherein said zoom lens is arranged to satisfy the following condition: 1<ν L.sub.2p -νL.sub.2n <30 where νL 2p : the Abbe's number of said double-convex positive lens component L 2p forming said cemented negative lens component L 2 in said first lens group G 1 νthe Abbe's number of said double-concave negative lens component L 2n forming said cemented negative lens component L 2 in said first lens group G 1 .
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