  For many years the FORS2 instrument has suffered from artefacts in the flat
fields caused by surface inhomogeneities on the longitudinal atmospheric
dispersion corrector (LADC) that affected high-precision photometric and
spectroscopic measurements. Recently, the FORS LADC prisms were exchanged, and
our analysis of a large number of flat fields shows that this exchange has
resulted in a significant decrease in the level of small-scale artefacts.
