The 3 elements optical system of RCC uses Phantom Coating for maximum light transmissivity. Adding the optional RCC off-axis guider (that is screwed to the RCC I corrector T2 thread and that is 36mm thick), you still have 55mm back focus then just add a T2 ring and the DSLR camera body to position the sensor at the correct working distance. If you want to connect the camera directly to the RCC I corrector T2 thread (without off-axis guider), you must also insert the necessary T2 extensions.
Designed for: Newton telescopes with f/3.5 to f/6 focal ratio
Backfocus (ideal distance from camera sensor): 91,5mm from T2 thread (+- 3mm)
Telescope connection: 50,8mm
Camera connection: T2 thread (M42x0.75)
Barrell diameter: 50,8 mm