  I discuss the modalities of zenith observing with LMTs, their limitations and
advantages. The main limitation comes from the relatively small regions of the
sky that LMTs can access. The main advantage comes from low cost, for
inexpensive large LMTs can be dedicated to very specialized goals. Large
surveys, cosmological studies, variability studies are prime examples of
astronomical research where LMTs can have a major impact. I examine the
performance of a 4-m telescope equipped with wide band filters and its use for
astronomical research. The data could be used to select targets for the VLT. I
examine the usage of the data for variability studies and, in particular, for a
supernova search.
