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

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Subject: Re: [Leica] APO
From: "Michael D. Turner" <mike@lcl-imaging.com>
Date: Sat, 06 Jun 1998 11:51:43 -0700

At 09:32 AM 6/6/1998 -0700, Paul and Paula Butzi, you wrote...
>Do you know, off hand, what the wavelengths for C, D, and F are?
>
>-Paul

C = 6562.816 , red, Hydrogen
D1 = 5895.944, yellow-orange, Sodium
D2 = 5889.977, "                  "
F = 4861.344, blue, Hydrogen

I think Erwin's saying (please correct me if I'm wrong!) that when
aberration is zero at the C and F lines, the wavelengths between are
corrected, but not necessarily zero. Zero aberration at the D lines would
greatly improve correction at the other wavelengths. I was surprised that
wavelengths beyond red and blue weren't chosen for correction since films
have sensitivity beyond that range. Should we be using UV filters to
improve sharpness? ;-)
- -Mike