  Optical/infrared photometry can double the number of proper motion
measurements of Massive Compact Objects (MACHOs) relative to single band
photometry. The proper motion of a MACHO can be measured by finding the ratio
$q$ of the (known) radius of the source star to the Einstein radius of the
MACHO, $q=\theta_s/\theta_e$. A classic method for doing this is to look for
the effect on the light curve of the finite size of the source. A modification
of this method proposed by Witt (1995) is to look for color changes in the
light curve due to the fact that the limb darkening of the source is different
in different bands. We demonstrate that the ``classical'' method is not
feasible unless the MACHO actually transits the source: if the MACHO passes at
say 1.5 source radii, there is still a sizable $\sim 5\%$ effect, but the light
curve cannot be distinguished from point-source light curves with different
parameters. However, color measurements in $V$ $(0.55\,\mu$m) and $H$
$(1.65\,\mu$m) reduce the errors by a factor $\sim 120$ and permit proper
motion measurements at impact parameters of up to 2 source radii. Color maps in
$V-H$ are also useful in the detection of planetary systems. Giant stars have a
``red ring'' in such maps. A planet which transits this ring gives rise to a
distinctive signature which can help in the measurement of the planetary
system's proper motion.
