RE: [APML] Focusing an ST-4

["Gene Horr" <genehorr@houston.rr.com>]

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Emmanuele Sordini

> Unfortunately I don't have an el-cheapo refractor of that class to devote
> to that for good.
> Well, that's not completely true: perhaps I could use an old 60 mm (700 mm
> FL) refractor of mine, but I think it's too small an aperture to be
useable
> with the average random guidestar I could run into, at least when doing
> deep-sky AP with FL's of 1000 mm or more. Or am I wrong perhaps?

You're wrong <VBG>.  Seriously, though, your 60mm 'scope optically should
make a darn good guide scope as long as it has a sturdy focuser that can
be locked.

> And I wonder: is a star absolutely necessary to to the tuning? Wouldn't a
> distant (i.e. a few miles) streetlight be enough?

Yes, but I don't remember off of the top of my head what that distance is.
I seem to remember that FL (and possibly aperture) was a factor but that
for most amateur scopes it was possible - seeing permitting.

Gene Horr
genehorr@houston.rr.com

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