  Recent weak lensing observations have pushed the use of 4 meter-class
telescopes to the limits of their capabilities with exposure times exceeding
several hours. The leading idea is that the surface density of faint galaxies
up to very faint magnitude ($B > 28-30$) raises continuously thus potentially
offering a dense template of distant sources whose intensity contrast is at the
sky noise level. In complement to the Peter Schneider's presentation on dark
matter search from weak lensing (this conference), we review some of these
recent advances in weak lensing analysis based on this extreme faint population
of galaxies in order to explore: the dark matter distribution on large scales,
the redshift ditribution of lensed sources at very large distance, and
eventually the values of cosmological parameters. For each observational topic
we will briefly discuss these new methods as compare to more classical lensing
studies as well as the possible VLT scientific impact in the domain.
