Upper panels: colour–colour diagrams for B-dropouts in the ERS (left) and HUDF (right) fields. Selected objects are marked in red, and the blue points indicate B-dropout candidates in the (B − V) vs. (V − Z) selection window excluded by the present analysis. Lower panel: combined photometric redshift probability distribution of our ERS B-dropout candidates (black line) and of galaxies selected from the (B − V) vs. (V − Z) diagram (blue dashed line): the (V − H) selected objects have a lower probability of having z_phot ≲ 3.5 solutions.