This is all from reading as I am new at this and have NO experience actually doing it.
My understanding with Digital is that you need a T-ring and T-adapter. Typically each camera maker has their own pair of the ring and adapter.
If you can add some weight to keep the center of gravity over the tripod/mount of the telescope that should help. Many telescopes are set up so you can make/buy counterweights.
What I have read indicates that when the camera body (no lenses) is attached directly to the telescope.
Digitial astrophotography has come a long way in the last few years. Film still has some advantages in some methods, but the noise issue has largely disappeared.
Most Digital SLRs have up to a 30 second shutter time. Some people will simply use multiple 30 second shots and then stack them with imaging software. Most cameras with cable or IR remotes also have a bulb setting which will keep the shutter open as long as you keep the button down.
Another method of astrophotography is to set the telescope up normally. Then set up the camera normally on a second tripod, pointed exactly at the eyepeice of the telescope. The camera should be set up (as I recall) the same distance away from the telescope as the focal length (edit- focal lenngth of the camera lens). The camera's focus should be set to infinity ('And Beyondddddd')... (sorry, couldn't help it).
If you are steady enough, you may be able to just hold and point the camera. I have a familial tremor so doing so is beyond my capabilities. (edit- this method is termed 'afocal')
Hope this helps some. I found a book on CD which has tons of information in it at
A Guide to Astrophotography with Digital SLR Cameras if you are interested.
