GB398307A - Improvements in variable focus lenses - Google Patents

Improvements in variable focus lenses

Info

Publication number
GB398307A
GB398307A GB1700032A GB1700032A GB398307A GB 398307 A GB398307 A GB 398307A GB 1700032 A GB1700032 A GB 1700032A GB 1700032 A GB1700032 A GB 1700032A GB 398307 A GB398307 A GB 398307A
Authority
GB
United Kingdom
Prior art keywords
members
focal lengths
focal length
focal
components
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB1700032A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kapella Ltd
Original Assignee
Kapella Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kapella Ltd filed Critical Kapella Ltd
Priority to GB1700032A priority Critical patent/GB398307A/en
Publication of GB398307A publication Critical patent/GB398307A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
    • G02B15/04—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by changing a part

Abstract

398,307. Lenses. WARMISHAM, A., 1625, Hinman Avenue, Evanston, Illinois, U.S.A. and KAPELLA, Ltd., 104, Stoughton Street, Leicester. June 16, 1932, No. 17000. [Class 97 (i).] A variable-focus lens comprises three members A, B, C, the members A, C both being dispersive and the member B collective. The focal length is varied by varying the separation of the members, the members A, C being moved simultaneously towards or away from the member B. In order to increase the focal length and at the same time maintain a fixed focal plane for an object at a given distance, the member B is moved away from the said plane and at the same time the members A, C are moved towards the member B. Preferably the member A comprises two separated components to facilitate simultaneous correction of astigmatism and distortion at the short focal lengths, and spherical aberration at the long focal lengths, and at least one of these components is compounded to render the member achromatic. To minimize aberrations of this member, both its components are preferably dispersive, one being a meniscus with its concavity facing the member B. The member C is compounded for achromatism and its cemented surface is collective to facilitate simultaneous correction of field aberrations at short focal lengths and axial spherical aberration at long. focal lengths. To facilitate correction of field aberrations at short focal lengths this member is made meniscusshaped with its concavity towards the member B. When the system is provided with mechanical means by which the movements of the members take place at rates suitable to an object at a given distance, it may be adapted for an object at a different distance by providing a supplementary lens E producing a virtual image at the said given distance from the system. Numerical data are given for the example shown having a minimum focal length of 1.61 with the members in the positions shown in dotted lines, and a maximum focal length of 5.78 with the members in the full line positions, the position of the focal plane being the same in each case.
GB1700032A 1932-06-16 1932-06-16 Improvements in variable focus lenses Expired GB398307A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1700032A GB398307A (en) 1932-06-16 1932-06-16 Improvements in variable focus lenses

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1700032A GB398307A (en) 1932-06-16 1932-06-16 Improvements in variable focus lenses

Publications (1)

Publication Number Publication Date
GB398307A true GB398307A (en) 1933-09-14

Family

ID=10087428

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1700032A Expired GB398307A (en) 1932-06-16 1932-06-16 Improvements in variable focus lenses

Country Status (1)

Country Link
GB (1) GB398307A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807983A (en) * 1955-11-14 1957-10-01 Farrand Optical Co Inc Five component high speed objective of modified gaussian type
DE1139292B (en) * 1957-06-04 1962-11-08 Farrand Optical Co Inc lens
US4247168A (en) 1977-11-15 1981-01-27 Gretag Aktiengesellschaft Zoom lens for photographic printers

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807983A (en) * 1955-11-14 1957-10-01 Farrand Optical Co Inc Five component high speed objective of modified gaussian type
DE1139292B (en) * 1957-06-04 1962-11-08 Farrand Optical Co Inc lens
US4247168A (en) 1977-11-15 1981-01-27 Gretag Aktiengesellschaft Zoom lens for photographic printers

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