  We present the composite luminosity function (hereafter LF) of galaxies for
80 Abell clusters studied in our survey of the Northern Hemisphere, using DPOSS
data in the framework of the CRoNaRio collaboration. Our determination of the
LF has been computed with very high accuracy thanks to the use of homogeneous
data both for the clusters and the control fields and to a local estimate of
the background, which takes into account the presence of large-scale structures
and of foreground clusters and groups.
  The global composite LF is quite flat down to M^+5 and it has a slope
alpha=-1.0 +/- 0.2 with minor variations from blue to red filters, and M^* =
-21.9,-22.0,-22.3 mag (H_0=50 km s^-1 Mpc^-1) in g, r and i filters,
respectively (errors are detailed in the text).
  We find a significant difference between rich and poor clusters supporting
the existence of an LF's dependence on the environment.
