Thanks Dennis! I will try to lower the frame rate back to 5fps like you suggest. Collimation is good, or as best as I could check anyway. I've used both methods I know of - i.e. stand 8-10 mirror diameters in front of the scope and look for concentricity as well as the defocussed star method as described in the manual. Maybe my concrete floor is shaking as you say.
Pity the moon isn't back for a while......
Oh well - I'll take it to the MAS forest session this Saturday and give it a go there.
Thanks for helping
