Hi Craige,
would recommend Astronomic CLS or the Astronomic CLS ccd.
The first is light pollution filter only and the second is light pollution plus IR cut filter as well.
You remove your eos lens and is inserted inside the camera.
http://www.bintel.com.au/Astrophotog...1/catmenu.aspx
http://www.astronomik.com/en/clip-filter-system.html
Regards
Kon