Cor - There is no artistic reason to measure Dmax. Save your money!
The important darkest value in a print is Zone 0 (assuming some type of
zone system is used). It must be remembered that the darkest value in
any print, even if zone 0 (or zone 000), will not be the maximum black
(Dmax) that that material is capable of producing. The useable range of
a photographic material almost never includes Dmax. However it does
include substrate base white. Paper selection is important.
What is important is the communication of the image. I have seen many
photographs in which there was no black (zone 0) at all, and these were
very moving photographs. I have seen high key photographs with no
values below zone V, and these were still great photographs. It all
really depends on what the photographer wants to do.
I would suggest that if one really wants maximum blacks that they print
in gelatine silver instead of alternative processes. Although again not
the blackest posible, this will be blacker than alternative processes.
Or paint. Why not? If one really wants that absolute blackness, just
paint it onto the print.
The more important question is how to see what values in a negative will
print as with the materials used and how do those values relate to the
photographer's seeing. This is answered with good, careful techniques
and lots of pratice.
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