L _{[O III]} from CLOUDY simulations as a function of cloud inner radii at a range of central stellar luminosity. The dust-to-gas mass ratio is assumed to be 1% in this case. The peak line luminosity occurs at similar radii, and is used to produce Figure 3 at different ejecta masses. The orange-shaded region reflects the observed PNLF bright-end cutoff at M ₅₀₀₇ = −4.53 ± 0.06 translated to line luminosity from Ciardullo (2012).