Re: [APML] need help getting round stars

["bert katzung" <katzung1@home.com>]

Hi Dick:
My 2 cents: I have used the Losmandy DSBS plate with the A-P 130 f6 and the
A-P 80 f11 guidescope and it works very well; nice round stars. I wouldn't
hesitate to drill and tap the end of the guidescope drawtube for another
thumbscrew. In fact, I did this to provide extra insurance on the A-P
guidescope, which starts out very solid. If the drawtube in your ST80 has to
be racked out quite a ways, it may not be leaving much tube inside the outer
barrel and this could result in changing flexure as the mount tracks. Less
at the zenith, more as the torque increases away from the zenith. If I
suspected this, I would add the second thumbscrew farther in from the end of
the drawtube, to provide more leverage against flexure. Maybe even inboard
of the focuser rack & pinion. Not having seen an ST up close I'm not sure
what the physical possibilities are, but if you don't mind drilling and
tapping (a pretty trivial operation), you could try these out before dumping
the ST.
Hope this helps....
Bert

Bert Katzung
"When it was first said that the sun stood still
and the world turned round, the common sense
of mankind declared the doctrine false; but the
old saying of Vox populi, vox Dei, as every philosopher
knows, cannot be trusted in science." CHARLES DARWIN
www.astronomy-images.com


----- Original Message -----
From: "Richard Locke" <dtlocke@flex.net>
To: <astro-photo@seds.org>
Sent: Monday, 29 October, 2001 8:33 AM
Subject: Re: [APML] need help getting round stars


> If I do decide to upgrade my guide scope, what's a good solid one to get
that will work out of the box?  I think AP has one, and that Orion is
selling one as well.
>
> -Dick
>
> ---------- Original Message ----------------------------------
> From: Matt BenDaniel <matt@starmatt.com>
> Reply-To: astro-photo@seds.org
> Date:  Mon, 29 Oct 2001 11:12:43 -0500
>
> >Richard Locke wrote:
> >>...
> >> Anyone else successfully using the Losmandy side saddle plates to
guide?
> >
> >Richard,
> >
> >Like Bobby, I prefer a top-mounted guide scope.  It is easier to balance
> >and is lighter and more compact.
> >
> >I did use the Losmandy DSBS for about a year and it worked fine.  It is
> >a very solid unit and has no flexure.  The problem is that it has more
> >weight and more angular intertia (especially in DEC), and it is more
> >work to balance.
> >
> >I do not believe that the DSBS is the source of flexure in your
> >situation.  Also the Losmandy plates and rings have worked very well for
> >me.  I have not seen any indications of flexure with them.
> >
> >Again, I think the problem is the ST80 focuser or clamshell/plate
> >interface.



--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>