Seeing that the weather at the moment has taken a turn for the worse and every night now seems to be a cloudy night i decided to modify my trusty old Canon 20D by fitting a Baader-ACF 2 DSLR correcting filter which replaces Canon's original filter giving full efficiency at H-Alpha wavelengths very simialr to the 20Da.
The Baader filter has to be self installed which does require some care but you can if you prefer send the camera away for it to be fitted by an increasing number of people which now carry out this mod for you but at a price of course.
For a very good guide on what is involved in fitting one of the above filters have a look at the Life Pixel site which has a step by step guide to what is involved on most Canon and Nikon cameras.
Inside a Canon 20D
Display removed exposing heat shield
Assembly with new Baader filter fitted