Make a quick measurement, calculate the correction value and adjust your mount sufficient for long-time photographic exposures!
For the alignment measure the drift of a star with a scaled eyepiece in arbitrary units during a certain time and correct your mount according to the calculation.
Start with the meridian adjustment, observing a star near the meridian in the south with a minimal elevation of about 45 deg. For obtaining the declination, place your phone flat on the telescope tube, pointing its top side to the star.
Then align the polar elevation, observing a rising star in the east or a setting star in the west. For correction, select a star near the meridian in the south.
For more info see http://leq.one-arcsec.org or www.strickling.net/aufstell.htm (German language)