I thought Margo was setup in prime focus Phil, maybe not.
Margo are you doing afocal or prime focus? I read SLR and adapter and immediately though prime focus. Are you taking the Pentax lens off and attaching the camera directly to the focuser on your dob or are you leaving the pentax lens on and shooting down the focus tube. If your leaving the lens on, you are trying afocal and for that you need to leave the dob eyepiece in. If afocal, what is happening is your camera is capturing an image of the secondary, off the primary, off the secondary off the inside of the camera, (if that makes sense). The same as when you take an eyepiece out and look down the focuser tube you can see your eye, the camera can see itself. Assuming of course that's what your doing (afocal)
