The possibility for exploiting an electronically addressed liquid crystal spatial light modulator as a phase filter, for optical correlators using incoherent light, is investigated. In such correlators, the phase filter must be specially designed with an iterative algorithm which takes into account certain degradations of the modulators. The degradations were considered in some detail. For the experiments, an electronically addressed liquid crystal spatial light modulator, derived from a commercially available video projector was adapted for use as the phase filter. The phase and amplitude modulation properties of this modulator were experimentally measured and full - 2π dynamic range for phase modulation was obtained, although accompanied by some parasitic amplitude modulation. This liquid crystal spatial light modulator was incorporated into an incoherent on-axis light correlator, to demonstrate successful updatable, real-time correlations.