Re: [APML] piggy back guide scope size

["Joseph/Leslie Schaefer" <schaefer@htva.net>]

Hi Larry,

  Hutech produces a focus lock that may help "some" with focus and mirror
shift. I haven't tried it yet but I intend to.
I use the Lumicon GEG in my setup but I need to use a focal reducer with my
ST-4 to get it to guide properly. You may
want to get some advice on this also. The GEG can accept 2" camera adaptors.
A separate guide scope is easier to use but with an SCT all the advice you
have been getting is right on.
The focus lock listed is for Celestron SCT's, you can check there web site
if you have a different brand.
  http://www.sciencecenter.net/hutech/misc/focuslk/index.htm
Joe Schaefer
www.starfillednights.com

----- Original Message -----
From: Larry McManus <lmcmanus@clearpointadv.com>
To: <astro-photo@seds.org>
Sent: Tuesday, October 15, 2002 7:20 PM
Subject: Re: [APML] piggy back guide scope size


> On my sc there is no mirror lockup. Does someone make an 2" OAG? If not
then
> is there a way to manufacture a piece to lock up my mirror?
> Larry
>
>
> on 10/15/02 3:47 PM, Alan Voetsch at critter12952@yahoo.com wrote:
>
> > --- Larry McManus <lmcmanus@clearpointadv.com> wrote:
> >> Can anyone give me a minnimum size for a guide scope
> >> to go on my sc. I have
> >> a 6 x 6 Hasselblad connected to the visual back of
> >> my 8" sc and I need to
> >> come up with a setup to allow me to guide on long
> >> exposures.
> >
> > Hey Larry,
> >
> > Kent's right. Because of the moving mirror in SCTs,
> > you are best advised to use an OAG, like a GEG or
> > Taurus T III. You could be guiding away perfectly
> > through a guidescope and there can still be any number
> > of ways that your shots will be wasted. Flexure,
> > mirror rotation, focus shift, OTA contraction due to
> > falling temperatures. Guidescopes on a SCT are a
> > crapshoot.
> >
> > Alan
> >
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