Re: [APML] Optimum focal length for guidescope?

["Chris Cook" <ccjd@ix.netcom.com>]

Stuart -

If you're using a ST-4 you can easily get away with less than a 1:1 guiding
ratio.  Currently I'm guiding my FS102 (which is 600mm @ f/6)with a 660mm
guidscope (60mm f/11 refractor).  If you are manually guiding, I would stick
with guiding with at least 200x.  Back before autoguiders, guys like Kim
Zussman in CA would guide at ~600x if I'm not mistaken.  Granted he was
shooting prime focus through a C11 @ f/10.

Chris

----------------------------------
Chris Cook
Astronomical & Nightscape Photography
www.abmedia.com/astro

-----Original Message-----
From: Stuart Heggie <stuart.j.heggie@sympatico.ca>
To: Discussion of Film Astrophotography <astro-photo@seds.org>
Date: Sunday, July 27, 2003 1:02 PM
Subject: [APML] Optimum focal length for guidescope?


>Okay - since it is quiet (and raining) I'll pose a question.
>
>As I look over my setup - I'm guiding a 400mm apo lens with a 1200mm
>guidescope. Seems odd to have 3x the focal length on the guidescope but
>seems to work. I may downsize the guidescope to fund the purchase of a
>new telescope. If the 400mm apo lens stays in the stable and I buy an
>800mm fl imaging scope - what would be an ideal focal length for a
>guidescope for both (i.e. for the 800mm Vixen R200SS - 8" f/4
>Newtonian)? I have a Vixen/Celestron 1000mm 102mm f/9.8 achromat now
>which I'm very pleased with and could continue to use.
>
>Stuart
>
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