Initial mass function of the cluster NGC 2244, in two different representations: dN/dM (top panel) and dN/d(log M) (bottom panel). The solid orange lines in the top panel show a power law fit with a break ∼1.5 M_⊙, with slopes α = 1.05 ± 0.02 at the low-mass side, and α = 2.26 ± 0.25 for the massive part. Two standard mass functions are shown as dotted (Kroupa 2001), and dashed (Chabrier 2005) lines, normalised to match the total number of objects that entered the IMF derivation. The vertical blue dashed line marks the completeness limit.