The Gravitational Lens Equation for Embedded Lenses; Magnification and
  Ellipticity
  We give the lens equation for light deflections caused by point mass
condensations in an otherwise spatially homogeneous and flat universe. We
assume the signal from a distant source is deflected by a single condensation
before it reaches the observer. We call this deflector an embedded lens because
the deflecting mass is part of the mean density. The embedded lens equation
differs from the conventional lens equation because the deflector mass is not
simply an addition to the cosmic mean. We prescribe an iteration scheme to
solve this new lens equation and use it to compare our results with standard
linear lensing theory. We also compute analytic expressions for the lowest
order corrections to image amplifications and distortions caused by
incorporating the lensing mass into the mean.
