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It also means "correct" Thus "right" which the translation
to the English language as "right"
Yanni
Marinated
S/V Princess Thalia
Hamilton
----- Original Message -----
From: "Bill" 
To: 
Sent: Thursday, January 26, 2006 11:09 PM
Subject: Re: Sextants with Polarizing filters


>> Actually "ortho" means vertical thus 90 degrees to the horizontal plane
>
> Wow, Through the (polarized) Looking Glass
>
> http://photography.about.com/library/glossary/bldef_ortho.htm
>
> "Definition:
>
> Orthochromatic films were first produced by Hermann Vogel in 1873 by
> adding
> small amounts of certain aniline based dyes to ordinary photo emulsions,
> work that was extended by others including J M Eder, who introduced the
> use
> of the red dye erythrosine in 1884.
>
> Early photographic materials were sensitive to blue light only, but ortho
> materials extended this to green in the middle of the visible region.
> Green
> is also the colour our eyes are most sensitive to, so this greatly
> improved
> the tonal rendition of photographs. Ortho materials can be handled using
> red
> safelights, and are commonly used for special black and white films for
> darkroom use - such as lith film."
>
> Off topic, but how does that "ortho" film relate to right angles?
>
> Alice?
>
>

   

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