After the completion of the catalogue built with ESO key program (REFLEX), we are beginning to explore the multiband optical characteristics of a subsample of those clusters selected in a statistically independent way. We have already observed in B, V, R, 9 of the about 50 clusters of the subsample, with 0.15 le z le 0.18. More time has been allocated by ESO for our project in March 2001. We will therefore be able to compare X-ray and optical morphologies and luminosities and, thanks to the large field of view of the WFI instrument, assess the luminosity function and the color segregation in the cluster on a robust statistical basis. In this poster we present the project, the technical problems we are facing in the reduction phase, and show the first preliminary results, which seem very encouraging.