What telescope mount do you use and do you use the guide chip for your autoguiding?
I still use the SBIG ST9XE camera on a 14" Meade GPS (vintage 2003) with a focal reducer at f/6.
I haven't use the internal guide chip for guiding in years. I use an SBIG external guide head with a TC237 chip (which I think is the same as the internal guide chip) on a 4" SCT piggy backed. The ST9XE generally reaches 15 mag in about 10 seconds if the star seeing FWHM is under about 3 asec. Guiding is usually not needed with the Meade 14" mount for exposures under 30 sec. Each ST9XE 20 micron pixel on the 14" at f/6 resolves about 1.95 asec, well below my location's atmospheric conditions, and I have not had guiding issues except for windy conditions above about 10 mph. If the exposure is going to be longer than 30 seconds then the remote guide head guider is automatically started by the software.
I have a ST-8XE and a ST-7XE that I use with a 8inch F4 newt on a AP900 mount.
Never used the guiding chip...I can guide for several minutes without any trailing so quite frankly never bothered with getting the guiding chip working. I have used a ST-i camera for a guider on the AP900 mount but never for variables.
I'm using an ST-9 (parallel port version) with a Meade 10" SCT on a 10Micron GM2000 mount. I never had much luck with the guiding chip; part of the problem is that coma gets pretty severe that far off-axis in my classic SCT and guiding SNR was always quite low because the guiding chip is behind the photometry filter.
I do my imaging unguided except during long time series for EB and Exoplanet stuff. Then I use a piece of software that measures drift (not periodic error) in the science images and performs guiding corrections (actually, "drift" corrections) multiple times during each exposure.
- Mark Munkacsy
The drift correction software is homemade. After each exposure it plate-solves the image, and feeds the resulting dec and RA position errors into a second-degree polynomial least squares fitter. Measurements are geometrically weighted so that the most recent images have the highest weight. The least-squares fitters (one for each axis) give the smoothed error, drift rate, and drift acceleration, which are then used to issue a guiding command before the start of the next image and then, in open-loop (extrapolated) control, every 10 seconds during the next image's exposure.
I had developed it to try and keep exoplanet host star images on the same pixel throughout an entire time sequence. It doesn't work that well, but it does keep stars in pretty much the same positions relative to dust donuts on my flats. (And it doesn't handle clouds all that well.) But, all in all, my exoplanet photometry with the filter turned on is better than when it's turned off.
I have never used the internal guide chip on any of my SBIG (ST and STL) cameras for the same reasons as MMU. Before I got the Paramount ME I would experiment to find the longest expsoure I could use which gave about a 95% yield of untrailed images. I used that exposure for faint targets and stacked enough of those to get good SNR's in the targets and comps.
The Paramount will track without trailing longer than I would ever need. For faint targets I use 120s exposures, then stack those. This distributes the risks from accidents, satellites, and airplanes.
I've run an ST-7XME for 15 years on 3 different telescopes. A Meade 12" LX-200, Celestron CPC-800 and Celestron CPC-925. I use the internal guiding chip all the time with no issues. I've never had any electrical issues with auto-guiding at all. I did have a very heavy dew somehow short the PC Control port on the LX-200 that blew the fuse in the front control panel. I've also run these telescopes down to -35 Celsius using areoshell grease in the gears. The telescopes still don't like it that cold but will work if the hand paddles are kept above freezing.
I use these cameras on two 14" LX-200 GPS and "R" telescopes. I use an ST-402 on separate 5" guide scopes for auto guiding. I don't use the internal guider for photometry as the chip sits behind the photometric filters but I do use it for spectroscopy using an SGS spectrograph.