A solar filter for a C8 and a PST are two entirely different kettle of fish(es). A standard solar filter only views in white light (albeit some produce coloured views
) and you will only see sunspots and transits, while the PST shows Hά so you will see prominences, flares, sunspots, plaque, filaments etc. All the really interesting stuff. They are great fun both for observing and imaging, especially with a DMK mono so you can do some false colour work with the image. Check out the Solar System forum for PST images.