Thanks Roger for your explanation - makes sense.
I think I may have to bite the bullet and hang out for a decent guide/imaging scope to complement the ed80. Perhaps a 66mm WO apo?
Load-wise it wouldn't traumatise the mount and would be an excellent wide field imaging scope too - I'll have to save a bit more, but the time will give me an opportunity to get used to the autoguiding setup and process with the ED80.
Thanks again.
Doug
...it's only money eh!?