Stanhope (optical bijou)
Stanhopes or Stanho-scopes are optical devices that enable the viewing of microphotographs without using a microscope. They were invented by René Dagron in 1857. Dagron bypassed the need for an expensive microscope to view the microscopic photographs by attaching the microphotograph at the end of a modified Stanhope lens. He called the devices bijoux photo-microscopiques or microscopic photo-jewelry. In 1862, Dagron displayed the devices at the Exhibition in London, where he got an "Honourable Mention" and presented them to Queen Victoria. In 1864 Dagron became famous when he produced a stanhope optical viewer which enabled the viewing of a microphotograph 1 square millimetre (0.0016 sq in), (equivalent in size to the head of a pin), that included the portraits of 450 people.
In 1851 John Benjamin Dancer invented microphotographs using a collodion process and a microscope converted to a camera. This resulted in a microphotograph about 3 square millimetres (0.0047 sq in) in area. The main disadvantage of Dancer's method was that the viewing of the microphotographs required a microscope which was at the time an expensive instrument. In 1857 Dagron solved the problem by inventing a method of mounting the microphotographs at the end of a small cylindrical lens. Dagron modified the Stanhope lens by sectioning the normally biconvex Stanhope lens and introducing a planar section so that the plane was located at the focal length of the convex side of the cylindrical lens. This produced a plano-convex lens, where Dagron was able to mount the microscopic photograph on the flat side of the lens using Canada balsam as adhesive. This arrangement enabled the picture to be focused.
|"If you look at the middle of the pearl eye in each nut you will see a little lens, through which you can see Paganini, Tourte and Stradivari. It’s a little joke which causes much amusement"|
The stanhope optical viewers were also mounted inside the bows of violins by French violin maker Jean-Baptiste Vuillaume, probably using Dagron's methods and equipment. The violin stanhopes featured the portraits of famous people such as Paganini, Tourte and Stradivari.
The sectioned lens could magnify the microphotograph three hundred times, so that the viewing of the microphotographs no longer required a bulky and expensive microscope. The modified Stanhope lens was small enough to be mounted in all manner of miniature artifacts such as rings, ivory miniatures, wooden toys etc. Dagron also designed a special microphotographic camera which could produce 450 exposures approximately 2 by 2 millimetres (0.079 in × 0.079 in) on a 4.5-by-8.5-centimetre (1.8 in × 3.3 in) wet collodion plate.
The success of his viewers enabled Dagron to purpose-build a factory dedicated to their production. As of June 1859, Dagron's factory was manufacturing the stanhopes, mounted in jewellery and souvenirs. In August 1859 he exhibited them at the International Exhibition in Paris where they met with great success. In 1862 he had 150 employees and was manufacturing 12,000 units a day.
In 1862 Dagron published his book Cylindres photo-microscopiques, montés et non montés sur bijoux.
In the early twentieth century Eugène Reymond took control of Dagron's stanhope lens factory in Gex, France. He was succeeded in the management of the factory by his son Roger. In 1972 the factory, run by Roger Remond, produced the last stanhope lens made by the traditional methods. In 1998, after Roger's death, the workshop was closed and its equipment dismantled and sold. Stanhope lenses are still manufactured to this day, but they are not produced according to Dagron's methodology.
In modern times, the most common stanhopes are usually gold or silver crosses with Christian prayers in the microphotograph.
- Focal encyclopedia of photography By Michael R. Peres Focal Press, 2007 ISBN 0-240-80740-5,ISBN 978-0-240-80740-9 846 pages
- The Strad Magazine October 2005 pp. 51-54
- The Photographic Journal By Royal Photographic Society of Great Britain Jan. 15 1864
- CHRONOLOGY OF MICROFILM DEVELOPMENTS 1800 – 1900 from UCLA
- La photographie et ses applications aux sciences, aux arts et à l'industrie Author Julien Lefèvre Publisher J.-B. Baillière et fils, 1888 Original from the University of Michigan Digitized Jan 13, 2009 381 pages p. 339 Quote: Prèmiere application: les bijoux photographique. "...Elles firent leur apparition aux expositions de 1859 et de 1867, sous la forme de petits carrés de la dimension d' une tête d'épingle et renfermés dans une petite lunette: sur ce carré l'on apercevait un grand nombre d'objets, par exemple les portraits des 450 députés de l'empire" Translation: "They made their appearance in the exhibitions of 1859 and 1867, in the form of small square the size of a pinhead and enclosed in a small telescope: in this square you could see a large number of objects, example the portraits of 450 members of the empire" provided by Google ,
Book in pdf
- Biographical dictionary of the history of technology By Lance Day, Ian McNeil ISBN 0-415-06042-7,ISBN 978-0-415-06042-4 p. 187
- A history and handbook of photography (1877) Author: Tissandier, Gaston, 1843-1899 Subject: Photography; Photography Publisher: New York : Scoville Manufacturing Quote: "It is a miniature microscope with considerable magnifying powers. The image seen through it is magnified about three hundred times." and "The lens used for toy micropliotographs resembles the Stanhope lens, but is not cut down in the centre to form a diaphragm. It consists simply of a cylinder of flint glass, or long plano-convex lens whose focus is its ovm plain surface, to which the photograph is attached with Canada balsam."
- George Eastman House
- Encyclopedia of Nineteenth-century Photography By John Hannavy Publisher CRC Press, 2008 ISBN 0-415-97235-3,ISBN 978-0-415-97235-2 1587 pages
- Scott, Jean (2002). Stanhopes: A Closer View--A History & Handbook For Collectors Of Microphotographic Novelties. Witham, United Kingdom: Greenlight. ISBN 978-1897738092.
- Dagron, René (1862). Cylindres photo-microscopiques, montés et non montés sur bijoux [Photo-microscopic cylinders, mounted and unmounted on jewelry] (in French).
- Who made stanhopes