Disappointing AstroTrac First Use

Well, I managed to get out and use my AstroTrac under reasonably dark skies just north of Cape Girardeau on the night of July 13/14. The moon didn’t set behind the hills until around 1:30 am, but I shot across the sky from it at M31 using my Borg 45ED. I used the laptop for control since my TC80-N3 is shot. I had an AC inverter to keep the laptop alive, but it didn’t have enough power and kept turning itself off. Ultimately, I was limited by when the laptop shut down. Since I was travelling light, dew was also an issue (no heater system) and I kept having to pull off the lens and use the car heater to clear the dew.

The biggest issue is tracking. There are two things I’ve noticed. First, it’s hard to polar align when the polar alignment scope has a scale problem. Second, each click stop in the AstroTrack for rotating the polar alignment scope to a new position has a slightly different take on where the pole is. The end result was that my 5-minute exposures all show slight trailing. I had the Canon 350D set to ISO 800 as a bit of a compromise between sensitivity and exposure length, but it looks like I’ll have to crank that to ISO 1600 and shoot more, shorter exposures. I need to gain some experience with this before next week when we go to the Summer Star Party. With the full moon and living in Brooklyn, I think I can get away with tests using the Lumicon "hydrogen alpha" filter to cut down the light levels enough to still do 3-6 minute exposures. Unlike a telescope, I’m not quite sure how I can get the AstroTrac aligned well. I don’t think I can practically do a drift alignment and I was hoping for short exposures to avoid the need to do so.