  For suitable gravitational lens systems with unknown lens redshifts, the
redshifts and brightnesses (in different colours) of the lenses are predicted
for a variety of cosmological models, for both elliptical and spiral galaxy
lenses. Besides providing hints as to which systems should be observed with a
realistic chance of measuring the lens redshifts, which are needed for detailed
lensing statistics and for modelling the lenses, these calculations give a
visual impression of the influence of the cosmological model in gravitational
lensing.
