This is what I use to connect my DSLR to my ED80.
It's an awesome piece of kit.
http://www.myastroshop.com.au/produc...sp?id=MAS-055B
I don't have to use an extension tube unless I add my Big Barlow into the imaging train. I have recently started wrapping plumbers tape around the barrel of the barlow to lessen the amount of flexure between it and the ext. tube.