That's a great way to save money too ie take the colour with the DSLR and then use the high res lum from the ST8. The RGB is the least important and very forgiving. I have had great success with crap RGB ie too little exposure and out of focus, you can blur it, minimise it chop it up into little pieces and even fry it
etc, as long as the Lum is excellent you can compile a good colour image. This is probably quicker too as its only two exposures instead of 4 needed for the LRGB technique
I took this 80ED data using a small chip CCD (equivalent res to a DSLR through a much longer FL I guess)
http://www.pbase.com/strongmanmike20...81518/original
blured it and used it as the colour for this image which took advantage of the high res Lum through the Starfire:
http://www.pbase.com/strongmanmike20...66688/original
Not ideal and I plan another smash at NGC 253 this year with better RGB but still a good result.
Nice Eta too, are you getting focus shift across the frame due to image plane tilt?
Mike