  We present an improved calibration of photometric metallicity indicators,
derived from the new metallicity scale for Globular Clusters presented by
Carretta & Gratton (1997) and based on direct high resolution spectroscopy of
160 stars in 24 globular clusters. We have carefully recalibrated the
traditional abundance indices based upon the red giant branch (RGB) morphology,
both in the V,B-V and V,V-I planes, namely the dereddened colour at the
luminosity level of the horizontal branch (HB), and the magnitude difference
between the HB and the RBG at a given dereddened colour. Finally, we give new
accurate relations to employ in the Simultaneous Metallicity Reddening method
by Sarajedini (1994), also tied to the Carretta & Gratton (1997) abundance
scale.
