Distribution of Galactic extinction A_X (in magnitude) for pD = 0.1 for a library of 2604 extragalactic source SEDs and a set of optical to near-infrared filters (0.005 mag bin size, purple to red for redder filters). In both panels, the vertical lines indicate the classically adopted photometric correction obtained by multiplying the reddening along the line of sight with a fixed value of the reddening curve at the filter pivot wavelength. The top panel shows the distribution of A_X (Eqs. (1) and (2)) assuming A_λ = 0.1 k_λ where band-pass corrections are neglected. The bottom panel shows the distribution of Galactic extinction, this time re-normalising first the absorption law adequately by applying the suited SED band-pass correction following A_λ = 0.1 k_λ/ bpc_sed.