  The Surface Brightness Fluctuations (SBF) Method for distance determinations
of elliptical galaxies is been modeled in order to investigate the effect of
the Point Spread Function (PSF). We developed a method to simulate observations
of SBF of galaxies having various properties and located at different
distances. We will use this method in order to test the accuracy on the
estimates of the extra-galactic distances for PSFs representing typical seeing
conditions, Adaptive Optics (AO) systems and for future observations with
Extremely Large Telescopes (ELTs) close to the diffraction limit.
