M/L vs. M projection of the FP in the SDSS r′-band, i.e. the relation log(M_s/L_s)_⊙ = log(M/L_r′)_⊙ vs. log M_s, where log M_s is the stellar mass enclosed within the half-light radius, in units of 10¹² M_⊙ and calculated according to Bell et al. (2003; left) and Gallazzi et al. (2005; right). L_r′ is the r′ luminosity enclosed within the half light radius. The small dots in both panels are the data from the catalog by Bernardi et al. (2010; priv. comm.), whose linear fit is shown as a continuous line. The big filled circles refer to our sets of models (12 models × 3 projection planes = 36 models) and the best fit of the intermediate and high mass models is shown as a dashed line. The dispersion of the models along the vertical axis, in particular for the high mass ones, is mainly due to their different initial conditions.