OK, Just FYI ..
SERies File Format is a video format. Registax6 apparently processes it.
http://www.er-c.org/cbb/info/TIAformat/
There is also a Planetary Image PrepPreprocessor (PIPP) software designed to strip out the worst frames before feeding them to Registax.
https://sites.google.com/site/astropipp/
Not where I wanted to go, I was aiming for long exposure DSO imaging so BMP is the only option I think unless I want to buy a mono camera and go to FITS.
Aaaah, the best laid plans of mice and men, how oft they go astray.