Strong field limit analysis of gravitational retrolensing

We present a complete treatment in the strong field limit of gravitational retrolensing by a static spherically symmetric compact object having a photon sphere. The results are compared with those corresponding to ordinary lensing in similar strong field situations. As examples of the application of the formalism, a super-massive black hole at the Galactic center and a stellar mass black hole in the Galactic halo are studied as retrolenses, in both cases using Schwarzschild and Reissner-Nordstrom geometries.