Thanks Roger! I wanted to open up the aperture a bit, but it wouldn't go below 5.6 - should go to 4.0, but obviously I haven't learned the trick yet (my first DSLR/first night!). I noticed you used Registar to overcome field rotation in your stacking. Registax did not work over the widefield, so my image wasn't a stack. Do you recommend Registar for this kind of work? (I've never used it). Thanks.
Cheers -
Rob