US5157552A
Expired / Lapsed
US
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Zoom lens system for a limited conjugate distance
Assignee: Minolta Co Ltd
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Filing: 1990-07-02
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Granted: 1992-10-20
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Expires: 2010-07-02
Abstract
Abstract A zoom lens system for a limited conjugate distance comprises at least three lens units which can be divided into, from an object side to an image side, a front lens group having a positive refracting power and a rear lens group having a positive refracting power. An axial distance between the front lens group and the rear lens group varies by a focusing operation. A zooming operation is performed by one of the front lens group and the rear lens group including at least two lens units. The zoom lens system fulfills the condition of l=m wherein l represents an object focal length of the zoom lens system, and m represents an axial distance between an object point and an object principal point of the front lens group.
Inventors
- 👤 Hitoshi Hagimori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:30
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/142; G02B15/1421
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
112 words
A zoom lens system for a limited conjugate distance comprising, from an object side to an image side; a front lens group and a rear lens group, both of which have a positive refractive power and one of which consists of two lens units, wherein a focusing operation is performed by moving the front lens group and a zooming operation is performed by varying the distance between said two lens units, the zoom lens system fulfills the following condition: l=m wherein l represents an object focal length of the front lens group, and m represents an axial distance between an object point and an object principal point of the front lens group.
Claim 2
Dependent Claim
112 words
A zoom lens system for a limited conjugate distance comprising, from an object side to an image side; a front lens group and a rear lens group, both of which have a positive refractive power and one of which consists of two lens units, wherein a focusing operation is performed by moving the front lens group and a zooming operation is performed by varying the distance between said two lens units, the zoom lens system fulfills the following condition: l=m wherein l represents an object focal length of the front lens group, and m represents an axial distance between an object point and an object principal point of the front lens group.
Claim 3
Dependent Claim
58 words
A zoom lens system according to claim 1, wherein the front lens group includes a first lens unit having a positive refracting power, and the rear lens group includes a second lens unit and a third lens, one of said second and third lens units having a positive refracting power and the other having a negative refracting power.
Claim 4
Dependent Claim
28 words
A zoom lens system according to claim 2, wherein the second lens unit has a negative refracting power, and the third lens unit has a positive refracting power.
Claim 5
Dependent Claim
76 words
A zoom lens system according to claim 3, which fulfills the following conditions: -2.5≦β≦-0.6 ##EQU17## wherein, β represents a magnification of the entire zoom lens system; f 2 represents a focal length of the second lens unit; f 23H represents a compound focal length of the second and the third lens units at a miximum magnification; and f 23L represents a compound focal length of the second and the third lens units at a minimum magnification.
Claim 6
Dependent Claim
57 words
A zoom lens system according to claim 4, wherein the first lens unit includes three lens elements, at least one of which is a negative lens; the second lens unit includes a negative bi-concave lens element and a positive lens element; the third lens unit includes four lens elements, one of which is a negative meniscus lens.
Claim 7
Dependent Claim
102 words
A zoom lens system according to claim 5, which fulfills the following conditions; ##EQU18## wherein, r p represents a radius of curvature of an object-side surface of the negative lens included in the first lens unit; r q represents a radius of curvature of an image-side surface of the negative lens included in the first lens unit; r s represents a radius of curvature of an object-side surface of the negative meniscus lens included in the third lens unit; and r T represents a radius of curvature of an image-side surface of the negative meniscus lens included in the third lens unit.
Claim 8
Dependent Claim
28 words
A zoom lens system according to claim 2, wherein the second lens unit has a positive refracting power, and the third lens unit has a negative refracting power.
Claim 9
Dependent Claim
56 words
A zoom lens system according to claim 7, which fulfills the following conditions: ##EQU19## -1.9≦β≦-0.8 wherein, β represents a magnification of the zoom lens system; f 23L represents a compound focal length of the second and the third lens units at the minimum magnification; and f 2 represents a focal length of the second lens unit.
Claim 10
Dependent Claim
52 words
A zoom lens system according to claim 8, wherein the first lens unit includes three lens elements, one of which is a negative lens, the second lens unit includes four lens elements, and the third lens unit includes three lens elements, at least one of which is a positive meniscus lens element.
Claim 11
Dependent Claim
102 words
A zoom lens system according to claim 9, which fulfill the following conditions: ##EQU20## wherein, r p represents a radius of curvature of an object-side surface of the negative lens included in the first lens unit; r q represents a radius of curvature of the image-side surface of the negative lens included in the first lens unit; r s represents a radius of curvature of an object-side surface of the negative meniscus lens included in the third lens unit; and r T represents a radius of curvature of an image-side surface of the negative meniscus lens included in the third lens unit.
Claim 12
Dependent Claim
59 words
A zoom lens system according to claim 1, wherein the front lens group includes a first lens unit and a second lens unit, one of said second and third lens units having a positive refracting power and the other having a negative refracting power, and the rear lens group includes a third lens unit having a positive refracting power.
Claim 13
Dependent Claim
28 words
A zoom lens system according to claim 11, wherein the first lens unit having a positive refracting power, and the second lens unit having a negative refracting power.
Claim 14
Dependent Claim
75 words
A zoom lens system according to claim 12, which fulfills the following conditions: 1.67≦β≦-0.4 ##EQU21## wherein, β represents a magnification of the zoom lens system; f 2 represents a focal length of the second lens unit; f 12H represents a compound focal length of the first and the second lens units at the maximum magnification; and f 12L represents a compound focal length of the first and the second lens units at the minimum magnification.
Claim 15
Dependent Claim
49 words
A zoom lens system according to claim 13, wherein the first lens unit includes four lens elements, one of which is a negative meniscus lens, the second lens unit includes a positive lens element and a negative bi-concave lens element, and the third lens unit includes three lens elements.
Claim 16
Dependent Claim
60 words
A zoom lens system according to claim 14, which fulfills the following conditions: ##EQU22## wherein, r x represents a radius of curature of an object-side surface of the negative meniscus lens included in the first lens unit; and r y represents a radius of curvature of an image-side surface of the negative meniscus lens included in the first lens unit.
Claim 17
Dependent Claim
28 words
A zoom lens system according to claim 11, wherein the first lens unit has a negative refracting power, and the second lens unit has a positive refracting power.
Claim 18
Dependent Claim
56 words
A zoom lens system according to claim 16, which fulfills the following conditions: ##EQU23## -1.25≦β≦-0.53 wherein, f 2 represents a focal length of the second lens unit; f 12H represents a compound focal length of the first and the second lens unit at the maximum magnification; and β represents the magnification of the entire lens system.
Claim 19
Dependent Claim
42 words
A zoom lens system according to claim 17, wherein the first lens unit includes three lens elements, one of which is a positive meniscus lens, the second lens unit includes four lens elements, and the third lens unit includes three lens elements.
Claim 20
Dependent Claim
60 words
A zoom lens system according to claim 18, which fulfills the following condition: ##EQU24## wherein, r a represents a radius of curvature of an object-side surface of the positive meniscus lens included in the first lens unit; and r b represents a radius of curvature of an image-side surface of the positive meniscus lens included in the first lens unit.
Claim 21
Dependent Claim
90 words
A zoom lens system for a limited conjugate distance comprising, from an object side to an image side; a front lens group and a rear lens group, both of which have a positive refractive power and one of which consists of two lens units, wherein a focusing operation is performed by moving the front lens group so that axial luminous flux, projected from the front lens group is substantially parallel to an optical axis, and wherein a zooming operation is performed by varying the distance between said two lens units.
Claim 22
Dependent Claim
90 words
A zoom lens system for a limited conjugate distance comprising, from an object side to an image side; a front lens group and a rear lens group, both of which have a positive refractive power and one of which consists of two lens units, wherein a focusing operation is performed by moving the front lens group so that axial luminous flux, projected from the front lens group is substantially parallel to an optical axis, and wherein a zooming operation is performed by varying the distance between said two lens units.
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