"It is difficult to state precise figures for the required negative density
range for any of these papers, as the highlight contrast of each of them is
rather low, and it is difficult to know whether to look for paper white or
highest discernable tonal separation."
I look for the highlights where there is a discernible change in tone, however
subtle.
The shadow and mid tones on the silver print-out papers and the platinum
papers have relatively high contrast. Hence the feeling of openness and
brilliance in a silver print-out or platinum paper.
That must be a subjective reaction. What I tend to look for is subtlety of
gradation across the density range or across any part of that range which can
certainly be obtained in pt/pd printing.
By comparison, a DOP like Ilford Multigrade FB with a "00" filter also
requires a negative of about 1.80 density range to print fully, but its
characteristic curve is quite linear. A silver print-out paper or a platinum
paper will represent the same negative with quite open mid-tones and shadows
(higher contrst), but soft highlights. That's why, side by side, a DOP will
frequently look weighted down compared to a silver POP or a platinum print,
even though they are representing the same negative. It's not merely the
color or the paper surface that's the difference, its the manner in which the
shape of the characteristic curve renders the tonal values in each part of
the negative's scale. Even in reproduction, you can tell the difference.
But that is if the Multigrade print is made using only the 00 filter. Try
printing in the shadows with the number 5 filter and see the difference it
makes. The excitement of the platinum print tones will reappear.
The relatively low highlight contrast in silver print-out papers and in
platinum papers, dictates the use of long scale, linear negative materials.
Because the printing paper will soften the highlights, one whould want to
avoid making negatives with highlights placed anywhere near a negative
material's shoulder. There are very few panchromatic films which can remain
linear over the density range required of these contact processes. The two
best appear to be Ilford FP4+ and Agfa P330p. (But this should be a different
subject.)
That is why I recommend FP4 for contact printing processes that require a linear
negative over this range. Kodak's Sep Neg 2 does the job quite well too.
And many thanks for these useful comments.
It is interesting that everyone else seems to get excited about platinum papers
being unable to achieve the same relection densities (blacks) as silver
gelatine, but you say that the difficulty lies at the other end of the scale.
In terms of perception a pt/pd print made from a long straight line negative
shot specifically for the purpose is unbeatable but a Classic Art print
developed in amidol or a split graded Multigrade print both have qualities that
put them at much the same level. But they are different and thank the Lord for
that.
Terry King