Hi Roof, welcome to IIS.
There's a few discussions here on IIS about similar problems focusing a DSLR on a newtonian at prime focus. It usually can't be done without moving the mirror up the tube. The problem is usually in-focus.
So, you can either do that, or use afocal methods. ie: put an eyepiece in, and use the lens on the camera, and shove the 2 together
