RE: Best CI for process

From: Eric Neilsen ^lt;[email protected]>
Date: 10/03/05-03:36:56 PM Z
Message-id: <20051003213657.E7C5976F0E@spamf4.usask.ca>

Sandy, If by intelligent you mean that we all need to agree that there are
not absolute places to start to evaluate a curve, or straight line? There
are not absolute places. There are points of absolute density. ES and CI are
based upon interpretation of useful information that can be arbitrarily
applied.

If you are only printing 12 steps on a 21 step scale, one that has densities
range from 0.0 to 3.0, with step 1 and 2 blending and you are only getting
to step 13 before paper white with pure palladium, then our processes are as
different in capabilities as to be creating confusion.

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 

> -----Original Message-----
> From: Sandy King [mailto:sanking@clemson.edu]
> Sent: Monday, October 03, 2005 4:11 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: Best CI for process
>
> Clay,
>
> I do indeed use a figure of 90% black when plotting with the
> Winplotter program. This gives very close to the same value as when
> measuring a step wedge print in the way I just described to Mark,
> i.e. from the first step about pure paper white to the first shadow
> step that merges visually with the next one.
>
> What I have been trying to figure out from the beginning of this
> thread is is, 1) are Eric and Emille using options which give a much
> longer ES than I am used to in my work, or 2) are we simply using
> terminology and practice that does not allow us to communicate
> intelligently on the subject?
>
> I still have not figured out which is the case, though some of the
> recent communications are making me lean toward the second of the two
> possibilities.
>
> Sandy
>
>
>
>
>
>
> >Is this exposure scale derived by counting 21-step Stouffer tables
> discernable
> >steps and multiplying by .15? The reason I ask is that I'm betting Sandy
> is
> >using the BTZS plotter program, and the way it calculates exposure scale
> is
> >predicated on picking a maxium black value. I know that Dick Arentz uses
> 90%
> >black for his work....
> >
> >Quoting Eric Neilsen <e.neilsen@worldnet.att.net>:
> >
> >> Sandy, I don't use or test a pure palladium. The smallest amount of
> platinum
> >> that I add is 15% of total metal salt solution. I make my own ferric
> oxalate
> >> and use a palladium solution that is mixed at 5 g NaPd with 3.5g NaCl
> to
> >> make 40 ml. This makes a .7 M solution to match my .7 M ferric
> oxalate. The
> >> Platinum is a .457M solution in potassium version and .7M when I can
> get the
> >> ammonium version. The molarity may be off by +/- .015 as these are
> from
> >> memory but I don't think so.
> >>
> >> My exposure scale for the 1.0ml FO, .15ml K Pt, and .85ml Na Pd, is
> 2.45.
> >>
> >> I make most of my exposures after a 10 minute dry@ 100F and a 30
> minute
> >> humidification @60% RH. I process in Potassium Oxalate at both room
> temp of
> >> 70 and heated to 90F. The exposure test that produced the ES above was
> >> processed at 70F.
> >>
> >> These test were also performed with Starphire glass in the contacting
> >> printing frame.
> >>
> >>
> >>
> >>
> >> Eric Neilsen Photography
> >> 4101 Commerce Street, Suite 9
> >> Dallas, TX 75226
> >> 214-827-8301
> >>
> >>
Received on Mon Oct 3 15:37:22 2005

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