Colour−magnitude diagrams of all clusters. The left panels show metal-rich clusters, middle panels are intermediate-metallicity clusters, and right panels correspond to the more metal-poor ones. All stars within 2 × r_half−light are plotted, without any cleaning procedure. Dartmouth isochrones with literature parameters (Table 2) are overplotted. Selected RGB stars for spectroscopic observations are plotted in red. Reddening vectors are shown in each CMD based on E(B − V) listed in Table 2.