We discuss how a wide field imager with very high spatial
resolution on a relatively small telescope–but located in an observing
site with very good seeing–might constrain the
fraction of binary stars in Galactic globular clusters. We also mention
the role that the new data might play in investigating advanced evolutionary
phases of low-mass stars. Moreover, we discuss the role that an Extremely
Large Telescope might have on the longstanding problem of cosmic distances
and stellar populations. In particular, we discuss the impact that the detection
of Cepheids in galaxies at the distance of the Coma cluster and of RR Lyrae
stars in galaxies at the distance of the Virgo cluster might have on the
calibration of secondary distance indicators.