  It is well known that the surface brightness of elliptical galaxies and of
bulges of spiral galaxies is best fitted by the Sersic r^{1/n} profile. It is
thus interesting to explore the lensing properties of the Sersic model because
of its wide range of applicability. To this aim, we evaluate the lensing
potential, the deflection angle, the time delay between the images and the a
mplification for a circularly symmetric lens whose surface density is described
by the Sersic profile. We estimate the same quantities also adding a shear term
to the deflection potential in order to study (at the lowest order) the impact
of deviations from radial symmetry or the contribution from other nearby
lenses. Moreover, we investigate the systematic errors due to the use of a de
Vaucouleurs profile instead of the correct Sersic model also taking into
account the presence of a dark halo.
