<< Can someone explain to
me the "correct" way to determin density range with a step wedge. I (in my
isolation) have been taking my zone 8 value (very light greys with just a
"touch of detail", say it is step #13) and subtracting my step 2 value (as
dark as I can get and still hold a "touch of detail", say it is step 3). I
then take step 13 minus step 3 equals 10 steps or 5 stops. It works for
me, but is this standard??? Obviously, I've consentrated on the zones at
the threshold of detail, but some things I've read suggest that zone 1-9
(threshold of tone) might be the intenational standard?? I may soon be
teaching, and I've never understood if my method matches the rest of the
world. >>
First I would suggest you never use the term density range without saying
what you are determining the density range of. The step wedge tells you
about the density range of the negative that will record on your print. It
tells you nothing about the density range of the print.
Most step wedges that I have used have density steps of 0.15, which means
that 2 steps are equivalent to one stop.
Note that this does _not_ directly relate to the stop readings you would get
using a spot meter on the subject - the separation of these on the negative
will depend on the development you give the negative.
You'll excuse me if I am stating the obvious, but it was not clear from the
way you asked the question. If you are likely to be teaching this kind of
thing I would recommend a practical study using one of the many good books
related to the subject.
Peter Marshall
Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/cgi-uva/cgiwrap/~ds8s/Niepce/peter-m.cgi