Re: (Gum) Tonal scale

Joe,

Sorry, I missed the last part of your question.

I think the 90% of DMax that you are referring to is the ANSI standard
definition and relates to the H&D curve of any paper/emulsion or film—since the
shoulder and toe of the H&D curve exhibit less differenciation in tone per unit of
exposure as compared to the straight portion of the H&D curve, it is a
reference to what is a useable portion of the density range.

To my understanding, if you graph a process, such as Palladium, you have
exposure on the horizontal or X-Axis and that is the Exposure Zcale. On the
Y-Axis, or vertical axis, you have print density range.

I've had similar discussions with Dick Arentz, since we teach a workshop
together. Dick is doing a lot of his work now with digital negatives and the PDN
system—in spite of what he said about digital negatives in the first edition
of his book, heheheeh. We both agree that since you can exactly match the
exposure scale of an alt process with corresponding digital negative's density
range, that you have somewhat of a different critter than one has with the
traditional in-camera negative. It makes it easier to get deeper shadow and
highlight information/separation—though the paper/emulsion curve is what it is and
remains the same. Due to this type of matching of negative to alt process
paper/emulsion, I find it easier to conceptualize the density range of the
negative to include the entire range up to what gives paper white—so if I had a
digital step tablet with 256 steps, I would count the last step which gives
paper white, as part of the exposure scale. But again, that is not necessarily how
everyone else would do it. You can also factor out the base + fog, or the
density of the film substrate if you wish.

Best Wishes,
Mark Nelson

In a message dated 12/1/05 1:52:30 PM, jsmigiel@kvcc.edu writes:

> In order us to all be on the same page, the terms need precise working
> definitions.  How do you define "exposure scale" in your PDN System or
> in traditional processes?  What criteria are used?  What are the limits?
> Do you consider "exposure scale" to be equal to the "negative density
> range" (which IMO is a problematic description based on varying
> definitions by different authors), maximum to minimum transmissive
> density printed, 90% of d-max to some minimum density above paper white,
> or ???
>

Mark Nelson
Precision Digital Negatives
Received on Thu Dec 1 23:49:31 2005