  To obtain the accuracy now sought in the extragalactic distance scale through
standard candles and rulers, calibration of stellar photometry must be
improved. The sensitivity of the V-K color surface brightness relation is
examined here by means of model atmosphere fluxes. It has previously been
neglected, but is shown here to be a significant term in the error budget of a
recent high precision distance of the Large Magellanic Cloud, an anchor in
galaxy distances based on Cepheids.
