Re: [APML] STV or ST7E for guiding?...

["Stuart Heggie" <stuart.j.heggie@sympatico.ca>]

Hmmm. Sounds like you've really worked on this already. I did try an
experiment guiding my 800mm scope with a 180mm lens on the ST-7 and it
didn't work. Not subtle enough. I agree that the calibration step is
annoying. Seems to me my CCDSoft5 managed it though. Select a fov with
only one bright star in the middle and then it doesn't see the other
stars or have this move-off-the-chip problem. I think.

Stuart
http://www3.sympatico.ca/stuart.j.heggie/Stuart.J.Heggie/
Flesherton, Ontario, Canada

----- Original Message -----
From: "Jeff Crilly" <jlcapml@sbcglobal.net>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, May 08, 2004 3:38 PM
Subject: Re: [APML] STV or ST7E for guiding?...


> > Jeff - I have the same ST7E (using a 102mm Vixen achromat) and it is
> > indeed a beast. I use the CCDSoft 5.0 that came with mine and it
does
> > subframes which totally nails the download hassle. It is great. Do
you
> > have that software? Maybe CCDOps has subframe downloads? (i.e. click
and
> > drag a box around the star you are going to use and it seems to
figure
> > it out - was a bit of trial and error but it worked and
substantially
> > speeded this up for me).
>
> I am using CCDOps for guiding.  As far as I can tell it does subpixel
centroiding
> which is what the STV/237 does w/ the e-finder. (Btw, my understanding
> is that the St-4 does not do centroiding.)
>
> When guiding, CCDOps also does tiny subframes.  This is acceptable.
>
> However CCDOps doesnt do subframes when calibrating -- it needs to
> take 4 full frames (or is it 5?) and the download for those is a bit
long.
> The problem is that the first calibrate doesnt always work... CCDOps
> seems to choose the brightest star in the FOV.. if that star is close
> to the edge.. tough luck.. or if it moves out of the FOV, or if
another
> bright star moves in the FOV during one of the movements.  Hence, the
> calibrate is a hit-or-mis operation... I end up doing it about 4 times
> before its calibrated.
>
> CCDSoft5 had problems with the G11.  The old "x-y simultaneous" bug
> had crept back in to the shipping version of ccdsoft.  The bisque bros
> fixed it, and got me a new version last summer.  However, I've just
had
> better luck (?) getting CCDOps to work for calibrating and guiding.
>
> MaximDL/CCD is indeed much better for guiding.  I tried out the
> demo, but at the time couldnt justify the $340.  I'm considering of
> buying the new 4.0.
>
> For now, I'll probably stick with the ST7E and work out getting a
> shorter guidescope.  I have a 200mm fl pentax screw mount lens that
> I've used for wide field... this is one approach, or a shortube.
> The issue is focuser -- it has to be rigid.. hence a stellarvue
> or WO or tak would qualify.  The synta (what I'm using now --
> 80mm f/11) is ok, but even when "locked" its not rigid.
>
> jeff
>
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