Alethoscope

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Short description: 19th-century optical instrument for viewing photographs

The alethoscope, (from the Greek “true”, “exact” and “vision”) is an instrument for viewing single photographs with a lens to enlarge and to create some illusion of three-dimensionality.[1] It is is a sophisticated version of the peep show,[2] designed by Carlo Ponti of Venice before 1862.[3][4] The alethoscope, like the similar graphoscope which descends from the eighteenth century zograscope predating photography, was and is often confused with the stereoscope which was of a different design and effect. It is the earlier, smaller version of a megalethoscope.[5]

Invention

Optician, photographer and publisher of views for the tourist and art-connoisseur markets, Carlo Ponti invented the alethoscope in 1860. He presented the device to the Société française de photographie in 1861, then in April, to the Istituto di Scienze, Lettere ed Arti in Venice, earning an honourable mention there in May.[6] He obtained a patent in January 1862 and commenced marketing it and photographs to be viewed using the instrument.[3] His invention was awarded Grand Prix at the International Exhibition in London in 1862.[7]

The alethoscope was used to view photographic albumen prints that were colored, perforated and mounted on a curved frame. The alethoscope showed night effects when viewing pictures in transmitted light from a fitted oil or kerosine lamp or a daytime version of the same scene when lit by the reflected light from two side mirrors.

Effect

The alethoscope is capable of a certain illusion of relief. It enlarged photographic views through a wide, thick magnifying glass that creates an illusion of the subjects' plasticity, perspective depth and modelling. The instrument’s arrangement minimises surrounding indicators of depth that would let us know this is a flat picture, and also because the image is magnified to nearer the scale of the real scene the picture is depicting. As the light coming from the lens to the eyes is collimated, it confounds accommodation; the image appears suspended at an indeterminable range. The broad, thick lens could also enhance depth perception by creating binocular stereopsis, because each eye views the image through a different part of the magnifying glass; chromatic aberrations at the edges of the lens may contribute to chromostereopsis; and depth clues in the image, which were usually architectural interiors or exteriors showing perspective clues, help to create the illusion.[8][9]

References

  1. "Alethoscope", The Free Dictionary, https://www.thefreedictionary.com/Alethoscope, retrieved 2019-08-23 
  2. Wolf, Mark J.P. (2012) (in en). Before the crash : early video game history. Detroit: Wayne State U.P. pp. 36-7. ISBN 978-0-8143-3450-8. OCLC 809532788. http://worldcat.org/oclc/809532788. 
  3. 3.0 3.1 Paoli, Sylvia (2013). "Ponti, Carlo (c. 1822–1893) Optician and photographer". in Hannavy, John (in en). Encyclopedia of Nineteenth-Century Photography. Routledge. pp. 1144–1146. ISBN 978-0-203-94178-2. http://dx.doi.org/10.4324/9780203941782. 
  4. Mannoni, Laurent (1970). Le Mouvement Continué. Italy: Mazzotta. p. 196. ISBN 88-202-1164-5. 
  5. Magiche visioni prima del cinema : la Collezione Minici Zotti = Magic visions before the advent of the cinema : Minici Zotti Collection. Zotti Minici, Carlo Alberto., Museo di magiche visioni (Padua, Italy). Padova: Il poligrafo. 2001. ISBN 8871152999. OCLC 48824470. 
  6. Minici, Carlo Alberto Zotti (2001) (in it). Magic visions before the advent of the cinema. Il poligrafo. ISBN 978-88-7115-299-8. https://books.google.com/books?id=h6kfAQAAIAAJ&q=Alethoscope. 
  7. Ponti Carlo. Charles Ponti Opticien Et Photographe De S.m. Le Roi D'italie : Inventeur Et Fabriquant De L'alethoscope ... : Place S.l Marc N. 52. Venise Riva Degli Schiavoni (Quai) N. 4180. C. Ponti 1862. Advertisement for Ponti's photographs of Venice and Italy. Wood-engraved ill. of the medal awarded Ponti at the London International Exhibition of 1862. Printed on gray wove paper
  8. Verwiebe, Birgit (September 1995). "L’illusione nel tempo e nello spazio. Il megaletoscopio di Carlo Ponti, un apparecchio fotografi co degli anni 1860" (in it). Fotologia 16/17 (Autumn/Winter 1995): 53–61. 
  9. Bantjes, Rod (October 2021). "The Optical Machine's Asynchronic Progress: Perceptual Paradigms and 3-D Enhancement Technologies, 1700–1925". Technology and Culture (Johns Hopkins University Press) 62 (4): 1119-1142. doi:10.1353/tech.2021.0155. 

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