[LRflex] Little to do with Leica, but interesting photographic measurments....
- From: David Young <telyt@xxxxxxxxx>
- To: LRflex <leicareflex@xxxxxxxxxxxxx>
- Date: Wed, 16 Nov 2005 10:10:05 -0800
All:
Last week a friend gave me photocopies of the relevant pages from
several articles on Calotypes, Daguerreotypes, Heliography, etc., from
"A Dictionary of Arts, Manufactures and Mines" (A. Ure, 1860) .
It's fascinating reading, but in the Daguerreotype article (p 567) the
author talks about Voigtlander lenses and their apertures.
"Voigtland's lenses consist of two achromatic object-glasses, the first
nearest the object having an aperture of 18 lines, the second on of 19
lines; the solar focus of the two is 5 1/4 inches."
and later:
"Voigtland has recently made a camera with two object-glasses, as above
arranged, each having an aperture of 37 lines"
I inquired on a scholarly, photo history list, to which I belong, and
discovered that "lines" are a botanist's measure, there being 12 lines
to the inch. So the first lens has an aperture of 3.08 inches and a
focal length of 5 1/4 inches... or an aperture of f 3.5! Not bad for the
1850's!
I you're interested in more on odd, imperial units, check out:
http://www.gwydir.demon.co.uk/jo/units/length.htm.
--
David Young,
Logan Lake, BC
CANADA.
Personal Web-site at: http://www3.telus.net/~telyt
Leica Reflex Forum web-page: http://www3.telus.net/~telyt/lrflex.htm
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