LBC colour images of the confirmed cluster fields of Sect. 6.3. We assigned r-SLOAN and z-SLOAN images from the LBC to the blue and red channel of the colour image. The green channel was created from the mean of both bands. Overplotted red squares and green circles show cluster galaxies and spectroscopic sources outside our membership criteria, respectively. In panel f, which shows the cluster 2XMMp J133853.9+482033, we additionally highlight with purple squares the group of galaxies that was ruled out by the iterative sigma-clipping method (compare Sect. 6.3.6). North is up, east is left, and the images are centred on the respective X-ray position.