Photometric Redshifts and Gravitational Telescopes

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.