Thanks Andrew and Humayun
Humayun, I'm constantly surprised and pleased at how Ha really tightens up an image. I'm looking forward to trying out various binnings for RGB at some stage too for this and other objects. Nice to be able to collect useful Ha/Lum on objects from the city - I'm happy with what I've done with the 450D in the past with pollution filter, but I'm dying to go deeper now with the QHY. That SBIG should be here before too long?!