  The Digital Access to a Sky Century@Harvard (DASCH) project is digitizing the
~500,000 glass plate images obtained (full sky) by the Harvard College
Observatory from 1885-1992. Astrometry and photometry for each resolved object
are derived with photometric rms values of ~0.15mag for the initial photometry
analysis pipeline. Here we describe new developments for DASCH photometry,
applied to the Kepler field, that has yielded further improvements, including
better identification of image blends and plate defects by measuring image
profiles and astrometric deviations. A local calibration procedure using nearby
stars in a similar magnitude range as the program star (similar to what has
been done for visual photometry from the plates) yields additional improvement
for a net photometric rms ~0.1mag. We also describe statistical measures of
light curves that are now used in the DASCH pipeline processing to autonomously
identify new variables. The DASCH photometry methods described here are used in
the pipeline processing for the Data Releases of DASCH data (Grindlay et al.
2012; http://dasch.rc.fas.harvard.edu), as well as for the long-term variables
discovered by DASCH in the Kepler field (Tang et al, in preparation).
