Determination of the stellar mass completeness limit as a function of comoving distance for our galaxy sample (black dots). Due to the range in M/L_r, constraining the mass completeness limit of a flux limited sample is not straightforward. By keeping the M/L_r and the redshift of each source constant, we determined the stellar mass that each object would have if its flux was equal to the flux limit. These limiting mass values are shown in cyan, with higher dots at a given redshift having larger M/L_r values. We then divided our sample into bins of comoving distance, sorted the sources in each bin according to their luminosity, selected the faintest 20%, and determined the stellar mass below which 95% of these faint objects lie (Pozzetti et al. 2010). We repeated this procedure for each bin and thus obtained the limiting mass values that are shown as magenta squares. The mass completeness function M_lim(d), shown as the magenta dashed line, was then estimated by fitting an exponential curve to these limiting mass value in each comoving distance bin.