Top: CMDs of two example grid elements. Boxes indicate the UMS and PMS regions used in the control field selection, as well as the RC region used to determine the mean extinction (see Sect. 3.2 for details). The slope of the RC selection box is defined by the reddening vector. Bottom: corresponding Hess CMDs. Thin solid lines are PARSEC isochrones (Bressan et al. 2012) for log(t/yr) ∈ [9.5, 9.6, 9.7, 9.8] and Z = 0.0033 (left panel), and log(t/yr) ∈ [6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8] and Z = 0.008 (right panel). The assumed metallicities are typical for the age ranges (Rubele et al. 2012; Tatton et al. 2013). The isochrones are shifted by a distance modulus of 18.49 mag (de Grijs et al. 2014), and an extinction correction derived from the RC analysis (see text) is applied. The dotted line marks the typical 50% completeness level.