Re: negative density range determination

Joe,

I mean the first density that has a slight tone, i.e. the one that is
just a slight bit darker than pure paper white. It is what I consider
to be Zone VIII, i.e. "whites with some texture and delicate values,
not blank white."

Sandy

>Hi Sandy,
>
>Thanks for the reply. I'm wondering if you can clarify one point for
>me? When you say:
>"...to the first density just over paper white..."
>do you mean the first step printing as paper white, the last step with a
>slight tone darker than paper white (i.e., the one that is "under" paper
>white), or the second strip that prints paper white (i.e., the one that
>is "over" paper white)?
>
>Thanks again for the info.
>
>Joe
>
>
>>>> sanking@CLEMSON.EDU 09/13/04 8:59 AM >>>
>Joe,
>
>The numbers vary because the actual exposure scale (ES ) of the
>processes varies a lot depending on chemistry, working conditions,
>paper, exposing light, etc. This is true with all processes, not just
>cyanotype.
>
>And the actual way people figure density range also varies, in the
>same way that some people count Zones from II to VIII and others
>count from I to IX.
>
>In my own work I figure density range manually, i.e. by looking at a
>printed step wedge, from the first maximum density to the first
>density just over paper white. When I make this evaluation by looking
>at a step wedge I simply count the number of steps and multiply by
>log 0.15 (assuming a step wedge where each step represent
>approximately 1/2 stop).
>
>Some plotter programs may give different values because one can
>choose IDmax, say at either 90% of Dmax or at some other figure. I
>generally choose 90% of Dmax for Pt/Pd printing but a bit higher for
>carbon printing.
>
>The main thing is to apply consistency in your own work.
>
>Sandy
>
>
>
>
>
>
>
>
>
>
>>I haven't heard from anyone yet regarding the question I asked
>yesterday
>>so I am repeating it here (below) with a bit of example data culled
>from
>>several texts. Various authors are recommending the following density
>>ranges for cyanotype:
>>
>>Schaefer:1.60
>>James:1.40-1.60
>>Crawford:>1.60
>>Farber: 1.40 (and 1.8-2.6 for Ware's)
>>Barnier: 0.95-1.4 (and >2.0 for Ware's)
>>
>>The range given for Salted Paper is:
>>Schaefer:2.00-2.40
>>James:1.50-2.00
>>Crawford:>1.70
>>Farber: 1.60-1.80
>>Barnier: 1.80-2.00
>>
>>So, you can see recommendations vary considerably. Additionally, the
>>way the authors determine these numbers also varies.
>>
>>For example, James refers to the negative density range as the
>>difference between the densities of "the densest highlights with
>detail"
>>and the "thinnest shadows with detail."
>>
>>Crawford states the negative density range is that which prints "the
>>full range of tones from 'paper white' to the 'maximum black''' and
>that
>>the exposure range is equal to the difference in density between "the
>>minimum exposure to produce the first perceptible tone and the exposure
>>necessary to produce the deepest possible tones."
>>
>>Farber states the negative density range is "the difference between the
>>brightest highlight and the deepest shadow with some texture."
>>
>>To me, there is a difference between a density producing a tone (e.g.
>>Zone I & IX) and a density producing some texture (Zone II & VIII for
>>slight perceptible texture and zone III & VII for full texture) as well
>>as maximum and minimum values. But, these authors' definitions seem to
>>be measuring different values and reporting vastly different ranges.
>>
>>So, I ask again what is the standard for determining negative density
>>range (if there is one) and what sort of target ranges do various
>>practitioners on this list use for the processes listed below?
>>
>>Thanks again for any info from actual practice.
>>
>>Joe
>>
>>>>> jsmigiel@kvcc.edu 09/08/04 12:17 PM >>>
>>As a result of some recent testing of cyanotype emulsions I have a
>>question regarding reported optimum negative density ranges for the
>>various alternative processes. As I read through several texts and
>skim
>>past threads related to the subject on this list, I realize there is
> >wide variation in the actual range numbers reported as well as how
>these
>>figures are determined by individuals (and not everyone reports their
>>method).
>>
>>My take on the subject is that the range should be determined by
>>subtracting the negative density of a slightly textured shadow area
>from
>>the negative density value of a slightly textured highlight area. In
>>Zone system terms, I would subtract the net density of Zone II from
>Zone
>>VIII.
>>
>>Is this standard? Are there good/valid reasons to use a different pair
>>of numbers/zones in the calculation (e.g., Zones III and VII, or Zones
>I
>>and IX, or initial densities producing max black and paper white)?
>>
>>I would appreciate input on how individuals on the list determine the
>>density for various processes and also what target range values you use
>>for the following processes: gum bichromate, cyanotype, van dyke brown,
>>salted paper, Kentmere/Centennial POP, and albumen printing.
>>
>>Thanks for any data and/or method you care to share.
>>
>>Joe
Received on Mon Sep 13 08:51:03 2004