Log difference of the best-fit scaling relations from Eqs. D.28 and D.29 with the derived parameters θ∈ } a,F_b/Σ_eff,b{ as a function of the bulge effective radius. The variation in the Hernquist parameters a and F_b with R_eff,b was derived by generating a grid of Hernquist models, projecting each model along the line of sight, and fitting them with de Vaucouleurs profiles. In the range of bulge sizes we are interested in, the error on the parameters is around 5%.