  We present the effects due to alpha-element enhancement on surface brightness
fluctuation magnitudes and broad-band colors in order to investigate the
calibration zero-point. We study these effects at ages covering 0.1 to 13 Gyr
and metallicities of Z=0.0003 to 0.04 using the Teramo group's isochrones,
BaSTI. Our preliminary results indicate that alpha-enhanced models are needed
to match massive red galaxies while solar-scaled models are fine for dwarf blue
galaxies to reproduce their independently estimated ages and metallicities.
