Ken
you might like to check Jim Thommes site..he has done a lot of amazing things with a modified webcam, using narrow band filters. Jim has moved on recently to a more advanced camera -an Artemis- but look at his archives for some examples of his work with a basic webcam and filters
http://jthommes.com/Astro/
Fred:
superb image-as we have learnt to expect from you
Narayan