Thank you Ted and Andrew!
Yep, Ted, I intend to take very accurate flat frames. I started to last night, but, then, realised that my last focus position was for luminance, and, not hydrogen alpha. My Baader filters aren't parfocal, and, I haven't got around to determining filter offsets, just yet. I've got an issue with my RoboFocus in that FocusMax gives me perfect focus, but, the centre value keeps changing (so, filter offsets will likely not work for now). I think I need to up my duty cycle. But, I am loathe to touch anything at the moment. Will reconfigure everything once it's put on to my pier and after I've finished my current project.
Thanks, again, guys.
H