I don't really know how to put this, but what is the cause of when your imaging and you're locked onto a guide star and all seems to be humming along nicely, then exposure after exposure, the image drifts across the screen. Most notable when going from one filter colour to the next, and then when you line up the frames when processing, each colour is successively shifted by a few mm to the previous. Is this normal, is this field rotation requiring higher polar alignment. ****..how much better would it need to be. I can keep a star on the chip on the screen for over3/4 hour before it has drifted away to the edge-not good enough??
