David
You should try using a soft developer - such as Tetenal Centrabrom-S - on
multigrade paper with maximum yellow filtration -170Y on my enlarger - (or
on grade 0). This just about prints every step on my Kodak wedge - or at
least 19 of them (always a little difficult to judge) - so is getting pretty
close to the 3.0 you mention.
Of course for the longest scale you would probably have to brew your own
emulsion. It would have little practical use!
My argument is however to some extent a logical one - whether on film or
negative we are dealing with the same material - silver halide.
The whole business of printing so far as I am concerned is not actually to
do with matching long ranges on negatives. Some of my negatives do have
ranges of well over 2.0 but I print them (or parts of them) on much higher
grades than this would suggest by suitable burning and dodging to bring out
those parts of the picture that I want. Doubtless you do the same when
printing on normal bromide materials.
Peter Marshall
Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/cgi-uva/cgiwrap/~ds8s/Niepce/peter-m.cgi