  We consider the effect of binary stars on the main-sequence luminosity
functions observed in the core of globular clusters, with specific reference to
NGC 6752. We find that mass segregation results in an increased binary fraction
at fainter magnitudes along the main-sequence. If this effect is not taken into
account when analyzing luminosity functions, erroneous conclusions can be drawn
regarding the distribution of single stars, and the dynamical state of the
cluster. In the core of NGC 6752, our HST data reveal a flat luminosity
function, in agreement with previous results. However, when we correct for the
increasing binary fraction at faint magnitudes, the LF begins to fall
immediately below the turn-off. This effect appears to be confined to the inner
core radius of the cluster.
