I got a telescope a few years back and though it works well for looking through with human eyes, it's been close to impossible to use with with a digital SRL camera mounted at the eyepiece. The problem is that the camera body can't move close enough to the tube to obtain focus on objects futher away than about 20 metres. Of course, that's not very useful for a telescope (unless you'e into bird-watching).
The camera can be made to focus with the addition of a barlow lens, but the only one of those I have magnifies by a factor of two and adds some blurring, so that's not really an ideal solution either. What I really want is to put the camera at prime focus using only the primary and secondary mirror.
On one of my bi-annual google searches for a solution I stumbled across the suggestion of a Hubble style operation to mount the telescopes primary mirror a bit closer to the secondary mirror, so making the focal plane move a bit further away from the tube. However, the original post is rather low on detail.