Thanks again folks
IOTW! Much appreciated Mike.
BTW - You can see the very latest version of this image, where I have brought the background noise under control and done a better job on blending the stars.
http://www.martinpughastrophotograph...05NB_60pct.jpg
Greg - yes, even though the scope got delivered direct from Planewave fully collimated, it did move during its journey. So it was collimated at the site under superb seeing.
The blend here was standard SHO, with Ha processed as Luminance. As normal, each frame was correctly balanced before combining.
cheers
Martin