  We continue our series of papers on open cluster distances by comparing
multicolor photometry of single stars in the Hyades to theoretical isochrones
constructed with various color-temperature relations. After verifying that the
isochrone effective temperatures agree well with spectroscopically determined
values, we argue that mismatches between the photometry and the theoretical
colors likely arise from systematic errors in the color-temperature relations.
We then describe a method for empirically correcting the isochrones to match
the photometry, and discuss the dependence of the isochrone luminosity on
metallicity.
