[raymo]

Nice pics, but it sounds like you have the problem possessed by
certain brands of Dobs, of insufficient back focus. If your DSLR camera
is attached directly to the focuser with a T-ring, and will not rack in far enough to focus, that is your problem. Many Dobs are not designed with
imaging in mind. First, aim the scope at the moon, hold the camera up to the focuser[fully racked in, of course] without the T-ring fitted, so you can get nearer to the focuser.
If you can then reach focus, then this is definitely your problem.
To get round the problem, if you are very near to achieving focus with
the T-ring fitted, a lower profile focuser would do the job. Decent
focusers are not cheap though. Alternatively, you can move the primary mirror up the tube the required amount to achieve focus. You can ,
depending on the model of scope, play around with the primary mirror
adjusting screws to move the mirror up the tube a little.
raymo