[raymo]

Hi Niall, I don't understand how hanging a 500D on your scope screws up your tracking. Balance in itself should have no effect on tracking, unless it is so hugely out of whack that the motor hasn't got the strength to drive
it. I can switch from a 1.25" eyepiece, to a 2" EP, or to my 1100D in it's
experimental cool box, and not worry about balance. I have the same rig as you.
Just saw 5ash's post. Just a point; An extra tube ring and a weight will take you very close to your
mount's weight limit, and a little over the recommended max for imaging.
raymo