As Terry has not taken up this directly, perhaps he and some others on the
list may be interested in the answer.
It is actually very difficult to tell the negative range than a silver
gelatin print can cover as I can print more or less every step of the Kodak
No 2 step wedge - which is 20 steps (or 10 stops) with careful exposure and
appropriate development (possibly a little faith is require to resolve the
first and last, but certainly 18 are pretty clear.)
Since the negative is in any case a silver gelatin emulsion, all prints are
in any case limited by the range of that recording medium - which again is
around the same number of stops (this is why there are 10 Zones).
However let me stress again that this is not related to the quality of the
prints produced - just handy if you have overdeveloped your negative!
It is easy to get carried away with rhetoric about the qualities of the
prints produced by various alternative processes. But I think we should
avoid claims that cannot be substantiated. It must also help to know why we
use step tablets - what information they give us and how we can interpret
it. I don't have a suitable platinum scale with which to compare this (mine
would all have less steps), but I am pretty sure the following differences
would emerge:
1. The maximum density of the silver print would be higher
2. The white of the silver print would appear brighter (unless you use
optical brighteners in you platinum paper!)
3. The tones would appear more evenly spaced in the platinum - this would be
particularly apparent in the mid to dark greys (neg density around .8 to
1.25 in my example) which appear crowded together in the silver - and
conversely the light greys (1.7-2.45) would have slightly less
separation. Of course your silver test print may look different to mine
depending on the paper and developer used, but in general I would expect
a more even tonal separation for the Pt.
So - although you cannot produce a longer tonal range in the print or even
reproduce more from the negative you can get better separation of tones.
There are of course also other visual qualities of the platinum (or other
alt process) print.
Peter Marshall
Pictures on Fixing Shadows: ----------- http://fermi.clas.virginia.edu/~ds8s
Future Press and elsewhere... E-Mail: petermarshall@cix.compulink.co.uk