  We develop techniques to calculate the four Delta electromagnetic form
factors using lattice QCD, with particular emphasis on the sub-dominant
electric quadrupole form factor that probes deformation of the Delta. Results
are presented for pion masses down to approximately 350 MeV for three cases:
quenched QCD, two flavors of dynamical Wilson quarks, and three flavors of
quarks described by a mixed action combining domain wall valence quarks and
dynamical staggered sea quarks. The magnetic moment of the Delta is chirally
extrapolated to the physical point and the Delta charge density distributions
are discussed.
