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rec.photo.equipment.misc Discussion: Achille Victor Emile Daubresse, forgotten prism inventor

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From: John Savard (jsavard_at_email.domain.hidden)
Date: Tue Nov 02 2004 - 11:04:07 EST

In an old book on optics, among several examples of types of prisms used
in terrestrial telescopes to erect the image, was one called the
Daubresse prism.

It was a standard right-angle prism adjoined to a pentaprism.

Some web searches for additional information indicated that Daubresse
did in fact invent the pentaprism.

British patent 7035/1900 seems to be the only likely candidate for the
patent in which the pentaprism is described, since there is one diagram
which shows some sort of roof prism.

In addition, British patent 7650/1901 shows him as the inventor of
something else I noted as clever! You know those machines that you run
film through for editing: sometimes they have viewers in them so you can
also watch the film while moving it? I noticed that one I purchased,
instead of having a shutter, used a rotating prism with multiple sets of
parallel sides to move the image in the opposite direction of the
advance of the film. Achille Victor Emile Daubresse invented that as
well!

John Savard
http://home.ecn.ab.ca/~jsavard/index.html

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