What is the best setting for Dec calibration, Auto, North or South?
A. Generally when it comes to guiding you only need to guide in one direction North or South. In the Auto mode, PHD tries to keep you on one side of the worm gear and figure out which way this drift is. If it is in error, you will get star trailing on some number of the frames.Ideally, you will know or determine this drift yourself and keep PHD from having to reverse direction ever (Dec drift will only be in one direction). To do this, calibrate PHD with Dec correction off and let it guide and watch for drift. Once you know which way that star is drifting you can select either North or South then recalibrate PHD. The auto feature can come in handy when you happen to be guiding and the scope goes across the meridian. Since the star will reverse, having PHD in auto mode will automatically correct for the shift in the opposite direction. However, I recommend setting up so you don’t come near the meridian when doing image capture and select North or South accordingly.
