We recover the luminosity distributions over a wide range of absolute magnitude ( -24.5 < M _ { R } < -16.5 ) for a sample of seven rich southern galaxy clusters .
We find a large variation in the ratio of dwarf to giant galaxies , DGR : 0.8 \leq DGR \leq 3.1 .
This variation is shown to be inconsistent with a ubiquitous cluster luminosity function .
The DGR shows a smaller variation from cluster to cluster in the inner regions ( r \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle < $ } \kern - 6.0 pt \lower 1.72 pt \hbox { { $% \scriptstyle \sim$ } } } 0.56 Mpc ) .
Outside these regions we find the DGR to be strongly anti–correlated with the mean local projected galaxy density with the DGR increasing towards lower densities .
In addition the DGR in the outer regions shows some correlation with Bautz–Morgan type .
Radial analysis of the clusters indicate that the dwarf galaxies are less centrally clustered than the giants and form a significant halo around clusters .
We conclude that measurements of the total cluster luminosity distribution based on the inner core alone are likely to be severe underestimates of the dwarf component , the integrated cluster luminosity and the contribution of galaxy masses to the cluster ’ s total mass .
Further work is required to quantify this .
The observational evidence that the unrelaxed , lower density outer regions of clusters are dwarf–rich , adds credence to the recent evidence and conjecture that the field is a predominantly dwarf rich environment and that the dwarf galaxies are under–represented in measures of the local field luminosity function .

Keywords : galaxies : luminosity function , mass function - galaxies : evolution .