Comparison of present isochrones and CM diagrams for three selected globular clusters, see text. For each cluster the estimated values for age, distance modulus and reddening are labeled together with the metallicity, as calculated from the observed [Fe/H] value (see Sect. 3). Top left and top right panel: comparison for the globular cluster M92, in the (V,B − V) and in the (V, V − I) diagram, respectively. Bottom right panel: the same, but for the M3 cluster in the (V, B − V) diagram. Bottom left panel: the same, but for 47 Tuc cluster in the (V, B − V) diagram.