Japanese External Reverse Porro Prism Binoculars. VIRTUAL MUSEUM

Les origines de l'Allemand jumelles miniatures

Истоки немецкий миниатюрный бинокль

Los orígenes del alemán prismáticos en miniatura




Text Box: Additional Advertisements: Fata Morgana Binoculars Weitere Werbematerialien für „Fata Morgana“-Ferngläser. Annonces Supplémentaires: «Fata Morgana» Jumelles. Дополнительные рекламные объявления: «Fata Morgana» бинокль.   追加のアドバタイズメント:Fata Morgana双眼鏡.Ytterligare annonser: “Fata Morgana” kikare. Nuevos anuncios: «Fata Morgana» Prismáticos.

Fata Morgana advertisement by the optician ETZ & PRITCHARD in Charleston, West Virginia USA, June 1923

Fata Morgana advertisement by the jewelers William Wise & Son, Flatbush Ave at  Fulton & Nevins Streets, Brooklyn NY USA in 1922

Using Fata Morgana binoculars. „Fata Morgana“ Ferngläser im Gebrauch.

Jumelles «Fata Morgana» en cours d’utilization.

Optical Journal and Review of Optometry  Vol 49 Jan 1922

Text Box:   Precedent Design? Präzedenzfall -Design? Précédent design? Прецедент Дизайн? 先例のデザイン
   Prejudikat Design? Diseńo Prejudikat?

    An interesting pair of prismatic binoculars (or binocular telescope) exists in the Louwman Collection of Historic Telescopes in the Netherlands. They were created by Carston Diederick Ahrens (1837-1918), ...“the most famous maker of hand ground precision optical glass, polarizing Nicol prisms and quartz plates in the world during his lifetime” according to Stuart Talbot. Ahrens worked in and around London, England. The binoculars are of interest in the context of this website because the prism arrangement and physical presentation (though not the size or objective tubes) is similar to the design later used by Baumann in the Fata Morgana. Ahrens was issued a British patent number of 17102/84 on Dec 31, 1884. No patent details survive, and there is contemporary evidence the patent was not completed (exhibited, but not registered plus completed). Stuart Talbot notes that in “Binokularen Instrumenten” published by Carl Zeiss Jena historian Prof. Moritz von Rohr in 1920, Rohr states that Carston Ahrens applied for an  English patent for a double telescope in 1884, but the patent was not completed. Rohr stated that the firm of Carl Zeiss was in possession of an example of the Ahrens binoculars, but that Ahrens had not utilized the advantage of image erection by Porro prisms to result in shortened [objective] tubes.

   Zeiss subsequently did so with their 1894 compact binoculars, and then Baumann took miniaturization quite a further with his 1919 design.




Ahrens Photos courtesy of Peter Louwman

Louwman Collection of  Historic Telescopes, The Netherlands

It is amusing to note that the United Binocular Co of Chicago imported a reverse poro prism design that seems to be quite similar to the 1884 Ahrens binoculars, which they called “the Falcon”, for a short time around 1956. That design did not seem to persist, and was presumably not so popular. I have not yet obtained an example. They also sold monocular spotting scopes of a similar design, which seemed to be more popular, and seem to have been produced in larger quantities.

The following information is based on information from the article “C.D. Ahrens (1837-1918) Optical Prism Worker of Every Description” by Stuart Talbot, FRAS, published in The Bulletin of the Scientific  Instrument Society No 121 (2014), and provided to me by Peter Louwman. Additional information is from a history of C. D. Ahrens by Jean and Colin Gaskin which can be viewed at Peter Abrahams website at: http://home.europa.com/~telscope/temp/Gaskin.2011.C.D.Ahrens.pdf.

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