PNLF in M 105. Left: observed LF of PN candidates (grey crosses) and PNLF of the completeness-corrected (CC) sample as defined in Fig. 8 (101 PNe) without accounting for contamination by Ly-α emitting background galaxies (blue crosses). Triangles denote upper limits. The solid red line shows the Ly-α LF and its variance due to density fluctuations indicated by the shaded regions (Gronwall et al. 2007). Right: PNLF of the completeness-corrected PN sample after statistical subtraction of the Ly-α LF (black crosses). Triangles denote upper limits. The solid blue curve denotes the standard Ciardullo PNLF with c₂ = 0.307. The red line and shaded region denote our best-fit PNLF with c₂ = 0.96 ± 0.30 In both panels, magnitudes fainter than the limiting magnitude and brighter than the bright cut-off are shaded in grey.