Common imaging train

Sky-Watcher Esprit 100 flattener + ASI2600MM Pro + EFW 7×36 + OAG-L

The Esprit 100 flattener is 55 mm from its mating surface behind an M48 thread; its 40 mm image circle covers APS-C but not full frame. 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. Retailers quote several numbers for this flattener from different reference points; the tool uses the mating-surface one.