  We review the use of photometric redshifts in the particular context of
Gravitational Telescopes. We discuss on the possible application of such a
technique to the study of both the faint population of distant sources and the
properties of cluster lenses. Photometric reshifts could be used to derive the
redshift distribution and properties of a very faint subsample of high-z lensed
galaxies, otherwise out of reach. Concerning the mass distribution in lensing
clusters, photometric reshifts are strongly needed to scale the mass in weak
lensing analysis, and to characterize the lensing structure.
