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Subject: Re: [M]: Calculating True f-ratios
From: Bill Arnett
Reply To: mapug@shore.net
Date: Sat Jun 12 14:38:20 1999
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While you're here, how about checking out the
Astronomy Book
List ? |
At 10:51 PM -0400 6/11/99, Michael J. Cook wrote:
>I would like some comments/alternatives to calculating true f-ratios
>when using focal reducers....
Your method seems right but it depends on a couple of things that are
not all that well known: the apparent FOV and focal length of your
eyepiece. You'll get more accurate answers by using a Celestron
Microguide eyepiece or something similar that is more carefully
calibrated.
OTOH, does it really matter if you think your f ratio is 7.5 when
it's really 7.7?
Bill Arnett
http://www.seds.org/billa/
"Science is a way of trying not to fool yourself." -- Richard Feynman
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