Re: [ATM] Telescope motors speed

["Bob May" <rmay@nethere.com>]

Motor speed.  Technically, the drive on the telescope is a
constant speed.  The earth turns 360 degrees in a little under 24
hours (some three minutes and seconds less).  Here's the but!
The refraction of the sky near teh horizone does make the sky
move a little slower than higher in the sky.  For this, you can
go look up the King rate for telescope mnotion.  The effect isn't
that great and is really only visible in photographs taken near
the horizone.  A simple autoguider for photograph taking will
easily correct for this error without your ever noticing it.   A
nice long focal length 3" refractor will nicely suffice for a
decent scope for the autoguider and give you something different
to build.  The "standard" BK7-F4 glasses will work well and will
be fairly cheap in this size.  Also look at the Newport Glass
refractors for larger pieces of glass and you can take some of
the curve out of the surfaces for a longer FL seope without
problems.  The refractor also puts the camera end of the scope at
the bottom of the scope so there aren't a lot of wires dangling
all over the scope.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net


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