Example of the weights applied across the CMD for the q01b03_120M_M5 mother CMD. The weight of each pixel in the CMD is calculated as the inverse of the variance of the stellar ages in that pixel. The bundle defining the area where observed and model CMDs are compared is also shown. The bundle tightly delimits the mother CMD; a few pixels containing synthetic stars outside the bundle correspond to stars that have been scattered in the simulation of the observational errors.