Galaxy luminosity function of the Ophiuchus cluster in the “rectangle” region (covering the same physical size as for the Coma cluster; see text). Top: constant galactic extinction, bottom: individual galactic extinction correction. Left: subtraction of Yasuda background counts, and right: subtraction of Yasuda background counts multiplied by f = 0.7 (see Sect. 3.1). See caption of Fig. 5 for colour coordination of lines and curves.