Chris, try here...picked this up on here earlier this week...
http://www.noao.edu/outreach/kpvc/im...-software.html
Flats are used to remove such things as vignetting, dust bunnies and such. They provide a flat (and hopefully evenly illuminated) field that compensates for noise within the pictures you take. The noise is generated by uneven sensitivity across the pixels within the chip in your camera and the flat basically helps to cancel it out.
When you image DSO's, the best one's to start out with are the brighter, more prominent ones, such as Omega Centauri, M31, M8, Eta Carina, LMC/Tarantula Nebula etc. The brighter ones are easier to image (or should be). You still have to make up a series of subframes and then stack them, but you'll find them easier to handle than going to objects like PN's and smaller, dimmer galaxies etc. Your 840K will take upto 60fps, so if you wanted to get a good shot of, say, Omega Centauri, I would take a 1 hour avi of the glob and then crop out the best pics in the bunch. Try to strive to get 300-400 stills or more. 800 is even better. Then you can calibrate and stack them using Registax, perform preprocessing and then export the subsequent file to your IP software for further work.
Know what....have a talk with the Icemeister... I'm sure Mike would give you few good tips and advice. He's the webcam king
