Hey Dave, check out my Canon 1000D shot of Saturn (of course, you have already looked at it before......right?
) taken using a 5 x powermate and Backyard EOS in Planetary mode with the 5x bonus feature switched on.....
Its possible, as I have shown....next time I will whack the 2.5x barlow in the train as well to really give it some scale.
Here is the link
Cheers
Chris