|
The distance for back focus is entirely separate and NOT associated to the focus or the focuser's motion.
The distance from the sensor to the reducer/flattener needs to be fixed. Usually 55mm but can be other distances depending. Also the distance from the reducer/flattener to the sensor on the OAG needs to be the same. You can end up with odd shaped stars from the OAG not being in perfect alignment but it shouldn't bother guiding if PHD2 can still identify a core.
|