Colour-magnitude diagrams showing the red-sequence for all clusters analysed in this work. Only for RX J2129 we use the filters F435W and F814W because of its low redshift, for all remaining clusters we use the F814W and F160W bands. Orange circles indicate the spectroscopically confirmed members. The grey region shows our colour cut and the photometric redshift range used to select photometric members is quoted in the legend (see Sect. 3.2 for more details). Both criteria are used to select the photometric members that are indicated by magenta circles. A summary of the membership selection is shown in Table 3.