We present a wide field V -band imaging survey of approximately 1 deg ^ { 2 } ( \sim 7.2 ~ { } h ^ { -2 } _ { 75 } Mpc ^ { 2 } ) in the direction of the nearby cluster of galaxies Abell 2151 ( the Hercules Cluster ) .
The data are used to construct the luminosity function ( LF ) down to M _ { V } \approx - 14.85 , thus allowing us to study the dwarf galaxy population in A2151 for the first time .
The obtained global LF is well described by a Schechter function with best-fit parameters \alpha = -1.29 ^ { +0.09 } _ { -0.08 } and M _ { V } ^ { * } = -21.41 ^ { +0.44 } _ { -0.41 } .
The radial dependence of the LF was investigated , with the faint-end slope tending to be slightly steeper in the outermost regions and farther away than the virial radius .
Given the presence of significant substructure within the cluster , we also analysed the LFs in three different regions .
We find that the dwarf to giant ratio increases from the northern to the southern subcluster , and from low to high local density environments , although these variations are marginally significant ( less than 2 \sigma ) .