Evolution of the sensitivity of the SSP luminosity ℓ_λ,IMF(t_∗) with age using the upper and lower envelopes of SSP results (see text); the age (or better, age range) corresponding to a given sensibility, t_λ,x% can be directly compared with the limits quoted in Table 2 for the different luminosities. In ascending ages each set of two curves corresponds to Q(H), galex/FUV and NUV, and sdss/u, g, r, i and z. These curves can also be interpreted as the evolution of synthesis models under a constant SFR assumption, except for the normalization factor.