Re: [APML] guidescope / setup question

["Ray Kilburn" <AuroraCEA@earthlink.net>]

Probably referring to a typical piggy-back type guidescope mounting in which
the guidescope in this situation would extend significantly past the Newt
and would possible be in the field of view if it is 25" longer.  But your
side-by-side Losmandy mounting would work extremely well if you can balance
it and eliminate the flexure adequately.

*****************************************
Ray Kilburn
Culpeper, VA
USA
----- Original Message -----
From: "bert katzung" <katzung1@home.com>
To: <astro-photo@seds.org>
Sent: Friday, October 05, 2001 5:10 PM
Subject: Re: [APML] guidescope / setup question


> Hi Aike:
> I can't answer all of your questions, but I have tried guiding with an ETX
> and a refractor and I can tell you that you were given very bad advice
> there! Yes, flexure is always a problem, but so is mirror shift. The ETX
> focal length is just as long as the refractor you're considering so it has
> no advantage/disadvantage there. The ETX definitely has mirror shift,
which
> a refractor guidescope does not have. The focus shift with an ETX is much
> worse than with either refractor that I use. Yes the refractor OTA is much
> longer than the ETX but with good mounting, that should not be a problem.
I
> use the A-P 80 mm f11 guidescope with my 130 f6 refractor and a 160 f3.3
> Newtonian (Tak Epsilon) and it works very well with both. I put the
> guidescope on one side of a Losmandy side-by-side plate and the imaging
> scope on the other side. I frankly don't know what your dealers are
talking
> about in terms of "aligning" the guidescope to the imaging scope. As long
as
> your guidestar is within a degree or two of the target, you should have no
> significant field rotation. There is certainly no sense in trying to
> optically align the guidescope with the celestial pole or anything else.
The
> mount is what has to be aligned, and you should do that with the imaging
> scope, NOT the guidescope. I would suggest getting a pair of good heavy
> rings of the Losmandy type (I use 125 mm rings) and Losmandy plates, make
> sure every thing is snugged down good and tight, and stay with the
refractor
> guidescope.
> Hope this helps....
> Bert
>
> Bert Katzung
> katzung1@home.com
> www.astronomy-images.com
>
> ----- Original Message -----
> From: "Aike M. Voelker" <AikeM.Voelker-Jamin@t-online.de>
> To: <astro-photo@seds.org>
> Sent: Friday, October 05, 2001 12:51 PM
> Subject: [APML] guidescope / setup question
>
>
> >
> > Hi APML,
> >
> > after selling my LX 200, I am working on my new sepup for
> astrophotography.
> >
> > My first decision regarding the primary scope was to go for a fast
> Newtonian, a
> > Vixen R200SS, it's a 8" f/4 (800mm focal lenght) telescope.
> >
> > The second decision to be made was (is) the guidescope. I've recently
> purchased
> > a Vixen 80mm / 1200mm refractor, which I thought would be a perfect
> guidescope!
> > I'm planing to get myself a EQ6 (expected delivery by the end of
October),
> which
> > is a mount that carries up about to 35 pounds and is said to be as
> dependable as
> > the G11, but for a much more moderate price...
> >
> > But....
> >
> > After talking to some of my astronomical dealers, I've discovered that
> they see
> > a big problem in aligning the guidescope to the photographic scope. (The
> > guidescope would be about 25" londer than my main instrument).
> >
> > Furthermore, I've received the advise that I should go for a smaller
> guidescope
> > such as the Meade ETX in order to prevent flexure, alignement problems
of
> the
> > complete system.
> >
> > Here are my questions:
> >
> > - is anyone operating with a system comperable to mine?
> > - if so, what are the expieriences with it?
> > - how about the alignement of the two scopes when out in the field (I
> don't have
> >   a permanent setup, so I need to setup the whole stuff every single
night
> I
> >   am photographing!)?
> > - what kind of guidescope "brackets" are useful to ensure proper
accuracy?
> > - is the ETX a useful guidescope (mirror shift?)??? - I have read bad
> things
> >  about using a ETX as guidescope.....
> >
> > Any hints will be highly appreciated ,as I can't wait to get out in the
> field
> > again.
> >
> > I definatly don't want to loose "Clear Sky" time (very rare in the last
> while
> > anyways....), with a system that won't work at all.
> >
> > Thanks for any input,
> >
> > Clear Skies,
> >
> > Aike
> > http://www.astrophotography.de
> >
> >
> >
> >
> >
> >
> >
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>
>
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