Ultratelephoto photography is easily achieved with your telescope by purchasing this Celestron SLR Camera Adapter with Integral 2x Barlow Lens.  You'll need to take precautions to minimize vibrations, such as locking up the mirror if possible as well as using a cable release or remote control to fire the shutter.  This SLR adapter's got a built-in 2x barlow lens to assure that any telescope can achieve proper focus, but many telescopes will be able to use it with the barlow attachment removed if you prefer.  It will depend upon how much in-travel your focuser barrel has at its disposal.  It can, of course, also be used on a catadioptric scope which has a 1.25" focuser barrel.