Ming

I think that's only true for the later versions of the Sphinx (SXD2 in your case?). The original Sphinx SX + Starbook (what I have) is quite notorious for DEC backlash/tracking. I heard/read somewhere that this is due to the Sphinx trying to track in both DEC and RA after star alignments. I didn't really do any star alignments as I only used it with the ASIAIR, so not sure what's causing the lousy/erratic tracking in DEC. I'll try to play some more with the DEC backlash setting in Starbook and see whether that makes any difference...

not sure whether this has been resolved since the thread is a few months old, but I've had the same issue with my ASIAIR PRO + Sphinx SX combination when auto-guiding. Seems the trick is to set the slew speed to lowest (1) in ASIAIR telescope interface BEFORE starting auto-guide calibration. This worked for me, but still couldn't get very good guiding accuracy due to DEC backlash (?).