Has anyone used one of these on their SCT? They are supposed to help achieve better focus for imaging.

Havn't got one but you would still need the original focuser for coarse focus, using the Crayford for fine focus .
It won't cure mirror flop so I don't know how much it would be worth.
The standard focuser can be improved by fitting a disc of about 75mm diameter 15 mm thick over the standard knob. This wll give the effect of a fine focuser because moving the larger diameter "wheel" will give a finer control.
You can buy such things but I've only seen them on US websites.
Ron

Just found a website withe sort of thing I meant.
http://www.scopestuff.com/ss_foc9.htm

Ron

Thanks Ron. I read quite a bit about the SCT crayford focuser and people have said that for fine focusing it is excellent. the focusing disc seems a good idea as well!

I;ve just fitted one of the Focus discs to my SCT but not had any chance to try it yet!