Re: [ATM] secondary size dillemma

["Alan Scott" <alanne1956@hotmail.com>]

John and Mike,
  I also have seen an amazing change in contrast due to baffling.  I have a 
very dark baffle behind my secondary cage, which may not be quite long 
enough towards the primary.  It is the darkest astronomical felt that you 
have ever seen.  Having said that, there is an obvious change in contrast 
between my scope with or without a shroud.  The shroud helps in light 
polluted environments, or if there is a partial moon, or even durring the 
darkest night in a "black" area of the light pollution map.  I will never 
make a scope again that cannot hold a shroud.  Surprisingly, the shroud only 
goes about half way down to the prmary, and leaves the lower half of the 
telescope open.  Folks can shine a red light directly on the primary, and 
you cannot tell.  So, I conclude that a half length shroud is long enough.

  This setup was so dark about 2 weeks ago that you could look at the 
horsehead and see it with direct vision.  Not bad for a 12"!

  I have been told to add a much bigger baffle to the back of the scope, but 
am trying to keep the top of the scope as light as possible.  Thus, I prefer 
a very lightweight shroud over a stiff baffle with felt.  And, a big baffle 
doesn't work well with moonlight.

alan scott
http://www.xmission.com/~alanne/DS3Main.html
http://www.xmission.com/~alanne/AlbuquerqueAstronomy.html (search for Datil 
Wells)


>From: "John Sherman" <atm@mail.johnspics.com>
>Reply-To: atm@mail.johnspics.com
>To: <atm@atmlist.net>
>Subject: Re: [ATM] secondary size dillemma
>Date: Wed, 16 Nov 2005 17:23:52 -0500
>
>
>Hi Mike,
>
> >Going off on a tangent.... when I properly baffled the scope
> >I got an even bigger improvement.
>
>Ditto!! I have a shroud for below the UTA, a long extension tube above the 
>UTA, and a focuser baffle. Makes the background a lot darker than some open 
>scopes I've seen.
>
>Thanks,
>
>John
>
>
>
>
>
>
>
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