GB191401185A - Improvements in Lenses for Photographic and other purposes. - Google Patents

Improvements in Lenses for Photographic and other purposes.

Info

Publication number
GB191401185A
GB191401185A GB191401185DA GB191401185A GB 191401185 A GB191401185 A GB 191401185A GB 191401185D A GB191401185D A GB 191401185DA GB 191401185 A GB191401185 A GB 191401185A
Authority
GB
United Kingdom
Prior art keywords
combination
lenses
refractive index
focal length
negative
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
Inventor
Cyril Frederick Lan-Davis
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Application granted granted Critical
Publication of GB191401185A publication Critical patent/GB191401185A/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
    • G02B9/04—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having two components only

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

1185. Davis, C. F. Lan-. July 11. Lenses.- Relates to large-aperture lenses for photographic or other purposes, corrected for spherical, chromatic, and astigmatic aberrations and of either fixed or variable focal length, in which the focal lengths of the front and back combinations are of opposite sign, the focal length of the negative being approximately equal to or greater than that of the positive. Three constructions are described. In the construction shown in Fig. 1, the front combination A is a thick achromatie positive composed of two cemented lenses of high refractive index (larger than 1À54), the indices for the D line being practically identical, but the dispersions being different, and the back combination B is an achromatic negative composed of three cemented lenses, each of the exterior lenses being of high refract ve index (larger than 1À54), and the interior lens being of low refractive index (less than 1 54). In the second construction, the front combination remains the same, while the back combination is an achromatic negative composed of two cemented lenses ,the flint having a refractive index between 1À63 and 1À60, and the crown a refractive index between 1:51 and 1À545. In the third construction, the front combination is a negative achromatic combination, and the back a positive achromatic combination ; the crowns are of high refractive index (larger than 1À54), the focal length of the positive is approximately equal to that of the negative, and the back focus of the system is greater than the focal length. In all the constructions, the separations between the front and back components may be varied in order to give variable focal length. Constructional data are given in the Specification.
GB191401185D 1914-07-11 1914-07-11 Improvements in Lenses for Photographic and other purposes. Expired GB191401185A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB191401185T 1914-07-11

Publications (1)

Publication Number Publication Date
GB191401185A true GB191401185A (en) 1915-03-18

Family

ID=32581282

Family Applications (1)

Application Number Title Priority Date Filing Date
GB191401185D Expired GB191401185A (en) 1914-07-11 1914-07-11 Improvements in Lenses for Photographic and other purposes.

Country Status (1)

Country Link
GB (1) GB191401185A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543354A (en) * 1949-01-05 1951-02-27 Taylor Taylor & Hobson Ltd Optical objective of the telephoto type

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543354A (en) * 1949-01-05 1951-02-27 Taylor Taylor & Hobson Ltd Optical objective of the telephoto type

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