Thanks guys,
Lester: the image is a stack of 3X 422 seconds at ISO 1600, using the Canon 20Da on the CG5 mount, autoguided through a 100mm spotting scope fitted with a modded TOUCAM. I diddnt have the focal reducer on that night so the F ratio was F10. If it hadn't ben so low on the horizon by the time i started imaging it i would have tried more shots at lower ISO with longer exposure time but i knew i'd be lucky to get a couple of shots only before she went behind the trees near my norwest horizon, so i shot in 1600
I probably should have put the focal reducer on come to think of it...
frank