Ultra telephoto photography is easily achieved with your Schmidt-Cassegrain telescope in conjunction with this T-Mount Adapter from Celestron. 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.

First, remove the eyepiece. Next, attach the adapter where the eyepiece would normally be attached to the telescope, and screw in a t-mount adapter to the opposite end of the SLR camera adapter. Now you can attach your camera to the t-mount and you are ready to begin taking pictures.