  We have imaged $\sim$ 1 deg$^{2}$ in the V-band in the direction of the
Hercules Cluster (Abell 2151). The data are used to compute for the first time
the luminosity function (LF) of galaxies in the cluster down to the dwarf
regime (M$_{lim}$ $\sim$ -13.85). The global LF is well described by a
Schechter function (\cite{schechter76}) with best-fit parameters $\alpha$ =
-1.30 $\pm$ 0.06 and M$_V$$^*$ = -21.25 $\pm$ 0.25. The radial dependence of
the LF has also been studied, finding that it turns out to be almost constant
within the errors even further away than the virial radius. Given the presence
of significant substructure within the cluster, we have analized the LFs in
different regions. While two of the subclusters present LFs consistent with
each other and with the global one, the southernmost one exhibits a somewhat
steeper faint-end slope.
