Hi Doug - I use a software program called Image Stacker. I found it at: http://www.tawbaware.com. This is one of many programs offered by Max Lyons, who is a panoramic image guru in my book! I use his PTAssembler program for stitching muliple (panoramic style) images together. It is great!

There's a link to Image Stacker from the Tawbaware main page. It's a shareware program, and the $17 I paid to register it was well worth the price. It offers different options, from stacking, averaging, and brightening of images, plus even dark frame subtraction (which I haven't used yet, but need to).

Thanks for your comments and question.

Clear Skies!

Photons are free. Take some!