Re: [APML] 500mm mirror lens as a guidescope?

[George Anderson <georgea@cam.org>]

Thanks Chris

That is the sort of info that I was looking for. I believe that the QC
uses the same chip as the ST4 (albeit not cooled) so with a 50mm lens
being 1/10 the FL of the "guidescope" it shouldn't be a problem. As long
as nothing in the optical train moves about.
Once I get enough duct tape <BG> wrapped on this I'll give it a shot and
see how it does in the front yard (the NA Neb shows nicely on E-200
after 10 minutes with minimal sky fog) before I head out to darker skies
with one of my few prized rolls of supra 400.

George Anderson
Montreal Canada

Clear skies and good health

Chris Schur wrote:
> 
> George, well for st4 guiding, a 1x to 4x the focal length in inches guide
> scope works pretty well.  I guide my 12 inch FL schmidt with a 40 inch fl
> cass, and it works awsome.
> 
> Chris Schur
> 
> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org]On Behalf Of George Anderson
> Sent: Tuesday, September 02, 2003 7:57 PM
> To: APML
> Subject: [APML] 500mm mirror lens as a guidescope?
> 
> While messing around with getting my B&W quickcam autoguider working and
> starting to worry about focuser flexure on my el-cheepo guidescope I
> started wondering (dangerous habit)...
> For widefield shots with a 35mm camera (50mm lens or less) would a
> guidescope with a 500mm focal length be sufficient?
> The 500mm f/8 mirror lens I have is very lightweight and has no
> detectable barrel flexure. The effective aperture is only 62mm but that
> is only a touch smaller than my 70mm f/10 scope that I use for manual
> guiding.
> Any thoughts from those in the know?
> 
> George Anderson
> Montreal Canada
> 
> Clear skies and good health
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