Hi John I can strongly recommend Baader solar film. It gives excellent resolution and good contrast. I have used it over the years and found it very pleasing when used visually or when imaging. The secret is to keep the film loose when you fix it into its diy 'holder' and not taught as this will distort the image.
I should point out that you need to make sure that the filter holder is a firm fit on the scope and cannot fall or blow off in a wind.
http://www.baader-planetarium.com/sofifolie/bauanleitung_e.htmhttp://www.youtube.com/watch?v=EiDheBRZrg0
