Peter
DO NOT use a Ha filter for viewing or imaging the sun unless it is a specific solar filter. Usually these come as a set with at least 2 components and can be quite pricey.
If you attempt to use an ordinary Ha filter ( eg one of these
http://www.lumicon.com/store/c/33-Hy...a-Filters.aspx ) the best result is you will wreck the filter, or the scope or the camera or most likely all three. The other possibility is that if you attempt to use it visually you will destroy your eyesight.
Malcolm