  We have developed a method to calculate overdensities in multicolour surveys,
and compare the local density contrast measured in galaxy samples with
different redshift error distributions. We calculated overdensities for three
COMBO-17 fields, and identified a region in the CDFS, where the density is
lower by a factor of 2 compared to the other two fields. This is mainly due to
a deficiency of faint red galaxies. This result is in agreement with local
observations in the 2dF.
