Re: Ok, how did Hershel do it?
From: John Savard (jsavard_at_excxn.aNOSPAMb.cdn.invalid)
Date: 11/25/04
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Date: Thu, 25 Nov 2004 08:57:33 GMT
On Thu, 25 Nov 2004 08:32:39 GMT, jsavard@excxn.aNOSPAMb.cdn.invalid
(John Savard) wrote, in part:
>And a telescope with a focal length of 40 feet, his largest, even if it
>had a focal ratio of only f/10, would then have a mirror at most four
>feet in diameter.
>
>If he had a telescope with a mirror three feet in diameter, 36 inches,
>50x per inch would still give 1800x magnification, and 60x per inch
>2160x magnification.
From
http://www.deutsches-museum.de/mum/dioramen/e_hersch.htm
I see that his 40-foot telescope was indeed f/10, so that means we're
dealing with a 48-inch mirror, allowing up to 4800x at 100x per inch -
which means only a slight amount of "empty" magnification, entirely
reasonable to ensure that the finest available detail is easy to see.
John Savard
http://home.ecn.ab.ca/~jsavard/index.html
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