US3682534A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Objectives of variable focal length
Assignee: Rank Organization Ltd
•
Filing: 1971-01-08
•
Granted: 1972-08-08
•
Expires: 1991-01-08
Abstract
Abstract A zoom lens front member which is divergent and is divided into two divergent parts, of which the rear part only is movable for focusing purposes, in accordance with the following relationships: 4.2 FA> fA1 > 1.5 FA 3.0 FA > fA2 > 1.3 FA 3.0 fA2 > fA1 > 0.6 fA2 where FA is the equivalent focal length of the complete objective when focused for infinity and fA1 and fA2 are the equivalent focal lengths of said front and rear parts.
Inventors
- 👤 Gordon Henry Cook
- 👤 Francois Rene Laurent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:37
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/142
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
141 words
In an optical objective of the zoom type having a stationary rear assembly and a front assembly which includes the members movable for zooming and a divergent front member by means of which the objective is focused but which, for a given object position, remains stationary during the zooming relative movements; an improved front member which is divided into divergent front and divergent rear parts of which only the rear part is movable for focusing purposes, which front member is characterized by the following relationships: 4.2 FA >fA1 >1.5 FA1, 3.0 FA > fA2 > 1.3 FA, 3.0 fA2 > fA1 > 0.6 fA2, where FA is the equivalent focal length of the complete front member for an infinitely distant object and fA1 aNd fA2 are the equivalent focal lengths of the front and rear parts, respectively, of the front member.
Claim 2
Dependent Claim
141 words
In an optical objective of the zoom type having a stationary rear assembly and a front assembly which includes the members movable for zooming and a divergent front member by means of which the objective is focused but which, for a given object position, remains stationary during the zooming relative movements; an improved front member which is divided into divergent front and divergent rear parts of which only the rear part is movable for focusing purposes, which front member is characterized by the following relationships: 4.2 FA >fA1 >1.5 FA1, 3.0 FA > fA2 > 1.3 FA, 3.0 fA2 > fA1 > 0.6 fA2, where FA is the equivalent focal length of the complete front member for an infinitely distant object and fA1 aNd fA2 are the equivalent focal lengths of the front and rear parts, respectively, of the front member.
Claim 3
Dependent Claim
31 words
A zoom objective front member according to claim 1, wherein: 3.3 FA > fA1 > 2.0 FA 2.6 FA > fA2 > 1.7 FA 2.0 fA2 > fA1 > 0.8 fA2
Claim 4
Dependent Claim
84 words
A zoom objective front member according to claim 1, wherein the rear part of the front member includes a collective element of a material having an Abbe V number less than 26, and at least one dispersive element of a material having an Abbe V number at least 1.9, times greater than the Abbe V number of said collective element, whilst the front part of the front member includes at least one dispersive element of a material having an Abbe V number exceeding 45,
Claim 5
Dependent Claim
52 words
A zoom objective front member according to claim 1, wherein the front part of the front member comprises two simple meniscus components convex to the front and the rear part of said member includes a compound component having a collective internal contact formed between two elements of materials differing in refractive index.
Claim 6
Dependent Claim
26 words
A zoom objective front member according to claim 4, wherein said internal contact has a radius of curvature numerically lying between 0.37 fA2 and 0.57 fA2.
Claim 7
Dependent Claim
68 words
A zoom objective front member according to claim 1, wherein the rear part of the front member comprises a doublet component spaced in front of a dispersive simple component, the front surface of said doublet component having a radius of curvature numerically between 1.1 fA2 and 3.5 fA2 the front surface of said simple component having a radius of curvature lying numerically between 0.45 fA2 and 0.7 fA2.
Claim 8
Dependent Claim
51 words
An optical objective having a front member according to claim 1, wherein the front assembly also comprises second, third and fourth members which are respectively convergent, divergent and convergent, the second and fourth members moving forward for zooming towards maximum focal length in association with rearward movement of the third member.
Claim 9
Dependent Claim
109 words
An optical objective according to claim 7, wherein: a. 2.5 Fm/N > f2 > f4 > f3 > 1 b. 1.5 Square Root R > 3 > g4 > g2 > 1, where Fm is the maximum value of the equivalent focal length of the complete objective; N is the f-number of the objective; f2, f3 and f4 are respectively the equivalent focal lengths of the second, third and fourth members; g2, g3 and g4 are respectively the ratios between maximum and minimum magnifications of the second, third and fourth members; and R is the ratio of the maximum to the minimum equivalent focal lengths of the complete objective.
Claim 10
Dependent Claim
15 words
An optical objective according to claim 8, wherein FA lies between f2 and 1.5 f2.
Claim 11
Dependent Claim
143 words
In an optical objective of the zoom type having a stationary rear assembly and a front assembly which includes the members movable for zooming and a divergent front member by means of which the objective is focused but which, for a given object position, remains stationary during the zooming relative movements; an improved front member which is divided into divergent front and divergent rear parts of which only the rear part is movable for focusing purposes, which front member is characterized by the following relationships: 4.2 FA > fA1 > 1.75 FA 3.0 FA > fA2 > 1.5 FA 2.7 fA2 > fA1 > 0.6 fA2 where FA is the equivalent focal length of the complete front member for an infinitely distant object and fA1 and fA2 are the equivalent focal lengths of the front and rear pats, respectively, of the front member.
Claim 12
Dependent Claim
143 words
In an optical objective of the zoom type having a stationary rear assembly and a front assembly which includes the members movable for zooming and a divergent front member by means of which the objective is focused but which, for a given object position, remains stationary during the zooming relative movements; an improved front member which is divided into divergent front and divergent rear parts of which only the rear part is movable for focusing purposes, which front member is characterized by the following relationships: 4.2 FA > fA1 > 1.75 FA 3.0 FA > fA2 > 1.5 FA 2.7 fA2 > fA1 > 0.6 fA2 where FA is the equivalent focal length of the complete front member for an infinitely distant object and fA1 and fA2 are the equivalent focal lengths of the front and rear pats, respectively, of the front member.
References Cited (Backward Citations)
US3481664A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |