Marc, your exposure is probably correct, but look at the edge of the unexposed film in the zone 5 print. When you get your zone 5 print, is the unexposed edge nice and black (do you see a tonal separation between the film base and the paper's edge)? If not, there isn't enough exposure. As you approach true black on the unexposed film's edge, does zone 5 come in at the same time? If true black is there prior to zone 5 showing up properly, you may have overexposed the film. tim