Hi Loris,

Just squeezing some info on bulbs, I am using 24" 20W BL368 (a set of 10 with some diy reflector in the back). Well,my exposure times are quite close to Loris's, differences are mostly from the base densities of different materials.

Sudek's 40 minutes exposure really sounds strange to me. Yet again I have no experience with DOP pt/pd, but I would not expect such long exposure.