Archived posting to the Leica Users Group, 1998/06/06

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Subject: Re: [Leica] Leica Nomenclature, should be APO
From: "Michael D. Turner" <mike@lcl-imaging.com>
Date: Sat, 06 Jun 1998 11:18:55 -0700

At 10:33 AM 6/6/1998 -0400, Dan Cardish, you wrote...
>I'm still looking for an explanation of what the word "APO" means.   And
>not a technical one about variable indices of refraction, etc.
>
>Dan C.
>
"apo-" is a Greek combining form meaning "away" or "from".
"a-" is also Greek meaning "without".
Hence, achromatic--without color (aberration).
Dictionary definitions of the words achromatic and apochromatic seem to
imply that they mean pretty much the same thing--without chromatic aberration.
To me, these words are essentially meaningless with out attaching some
specific technical meaning to them, as Erwin (thanks, Erwin, I've been
wondering about these terms for some time) has done.
- -Mike