Common imaging train

Takahashi FSQ-85EDX + 1.01× corrector + ASI2600MM Pro + EFW 7×36 + OAG-L

The FSQ-85EDX with its 1.01× corrector quotes a metal back distance just over the usual 55 mm. The mono train ZWO designed the pieces around: the camera keeps its tilt plate, the 7×36 wheel bolts to it, and the OAG-L bolts to the wheel with its M48 plate facing the telescope. The unmounted 36 mm filter glass still shifts focus slightly, and the 36 mm bore is the thing to watch on anything larger than APS-C. Just over 55 mm: the standard train plus a thin shim, with the camera-side thread to confirm on your ring.