The content of this section is in progress; you can contribute to making it better by sharing your experience with us.
There two ways of connecting devices to the optical path of the AP26-series cameras:
The M42x0.75 interior thread
This interior thread works well for attaching filter wheels, telescopes, filter holders, etc. If your device has a different diameter/thread, you may be able to use a thread adapter.
The 6 small holes with M2.5 threads
These 6 holes are distributed over a circumference of 62mm of diameter line up. They have an internal thread M2.5. These holes line up with the holes on the ZWO 2" EFW (or the holes on the "new" 36mm ZWO EFW). They also match the position of the holes of the QHY CFW-L, but you will have to purchase M2.5 screws because the screws provided by QHY are M3 thread.
The QHY filter wheels come with 6 screws that have an M3 thread. You can use a QHY filter wheel but must buy 6 (M2.5) screws. Amazon sells packs of different sizes. McMaster-Carr sells them very cheap. Also, you have to select the length that you need, probably 6 or 8 mm, depending on the thickness of the wall of the filter wheel. Again, buying different screws is only needed for QHY filter wheels.