Derived parameters of 10 000 artificial clusters with true extinction randomly chosen in the range of E(B − V) =  [0,0.5] with Gaussian photometric errors of 0.05 mag. Panels a), b), and c) show age, mass and extinction when a sample is studied using a grid of models with an allowed extinction in the range of [0, 1]; d), e), and f) show results for the same cluster sample studied with a narrower allowed extinction in the range of [0, 0.5]. Panels c) and f) are denser than in Fig. 3, because the same number of clusters are located on a smaller range of extinction. A square indicated in panels a) and d) is used to quantify the degeneracy effect.