Not directly related to the MF. See below:
'Dec guide mode' - gives you additional control over declination guiding. Declination guiding is not like RA guiding because the tracking errors are not caused by imperfections in your mount's drive system - the Dec motor is idle during normal sidereal tracking, running only in response to short Dec guide commands. Instead, tracking errors in declination are caused by polar alignment error, mechanical flexure, wind, binding or dragging of cables, or unwanted movement of the guiding assembly. Absent these mechanical problems, declination tracking should be smooth and mostly uni-directional assuming there is no over-shoot from an earlier correction. The default value of 'auto' tells PHD2 that some reversals in direction are acceptable, subject to the behavior of the various guiding algorithms. However, if your mount has severe declination backlash, you may want to prevent direction reversal altogether. You could then select either 'north' or 'south' to restrict corrections to only that direction (uni-directional Dec guiding). Keep in mind, however, that an over-shoot in correction with one of these modes might leave the star positioned off-target for an extended period of time. So you'll probably want to use conservative aggressiveness values for either 'North' or 'South' modes and you may want to intentionally degrade the polar alignment to help keep the drift rate larger than the deflections caused by seeing. Finally, a choice of 'off'' here disables declination guiding altogether, an appropriate choice for simple tracking mounts that don't support Dec guiding.
