[APML] fist images post... autoguiding with a webcam...

["Jeff Crilly" <jlcphoto@myrealbox.com>]

Hello folks.. 

I've been reading for a while here, and working on film technique.

Last year I picked up a G11 (standard, not-gemini), did wide field, then 
onto longer focal length.

The past few months (under bad weather here), I've been working on
an autoguiding setup using a webcam.  

Imo, I've finally got a couple simple single shot film images* that 
are worthy of posting that demonstrate the practicality of autoguiding
with the webcam....

M4 (20 min, iirc)  Provia 400F
http://fototime.com/156D77503E16D54/orig.jpg

M8... ngc6523 (30 min) Provia 400F
http://fototime.com/950EFD3E5310F34/standard.jpg
http://fototime.com/D27EF680CBEC4F6/standard.jpg

Large size M8 images...
Full Frame...
http://fototime.com/950EFD3E5310F34/orig.jpg
Cropped...
http://fototime.com/D27EF680CBEC4F6/orig.jpg

M13 (15 min, on Royal Gold 400 "select series")
http://fototime.com/747CD7EF0BA8861/orig.jpg

The scope setup...
http://fototime.com/CBCBB328F1E38EE/standard.jpg

The autoguiding camera is the ToUCam, unmodified but T-adapted for
attachment to the scope.   Th webcam talks to the PC using USB.

The autoguider software is freeware - David Ditch's StarTrack.
(http://www.davidditch.com/astro/startrack/index.html)
(I'm also working to get astrosnap working with the G11 ...
http://astrosnap.free.fr/index_uk.html
-- it seems to work with other mounts but there are some issues with the
G11 (simultaneous guiding adjustments) that the author Axel Canicio
has been kind enough to mod astrosnap for.

The setup is configured to send the guiding signals (essentially
the handbox button presses) out the parallel port of the PC
to a relay board which is then hooked to the Hand-Control
jack on the G11.

Last weekend I managed to get a couple decent shots on Provia 400F using a C102F f/9.   

The autoguider webcam was on a parallel mounted 80mm chinese scope.  

I polar aligned the mount (using the polar scope), but didnt do any 
drift alignment.  The PEC was turned off.  Autoguiding was done 
with the losmandy drive in the 0.5 setting.

Does it work?  Seems to.    One problem is that its difficult
to find a suitably bright guidestar for the webcam.  The ToUCam
is the most sensitive (afaik) off-the-shelf camera.  I suppose using
a flip mirror would make it easier to find guidestars. I've been
getting lucky finding them... sometimes its a challenge.)  There is
software to support long-exposure webcam mods (to enable
dimmer object imaging) however, I  backed away from 
hacking the camera -- too much surface mount stuff in there.

*Two other comments regarding the images above:

The above images were "scanned" using a 
nikon coolpix 990 camera with the ES-E28 slide
copying adapter -- not ideal, but works for examining
star roundness.  http://www.nikon.cz/digi_prisl_dia.htm

I note there is some off-axis coma in the images.  I'm
pretty sure this is simply the optics of the scope, its possible
this is from the slide copier, but I doubt it.

jeff

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