Enhancement δμ (mag) of broadband V, R, I and K magnitudes due to nebular (line and continuum) emission vs. EW(Hα) (Å). The left-hand panel shows a close-up view within 60≤EW(Hα) (Å)≤340 whereas determinations for an EW(Hα) of up to 1600 Å are shown in the right-hand panel. Symbols and lines in the left-hand panel have the same meaning as in Fig. A.7. Curves in the right-hand panel show polynomial fits in the range 60≤EW(Hα) (Å)≤1600 for predictions referring to continuous SF and a metallicity Z_⊙/5 (cf. Table A.1).