Common imaging train

WO Flat6AIII + ASI2600MM Pro + EFW 7×36 + OAG-L

The Flat6AIII is adjustable: dial its helical ring to William Optics' per-telescope figure and build the standard 55 mm behind the M48×0.75 T-mount thread. 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. Dial the ring first, then the ZWO train lands on 55 — the filter shift is what the shim is for.