RE: Best CI for process

From: Sandy King ^lt;[email protected]>
Date: 10/03/05-03:48:58 PM Z
Message-id: <a06020423bf67571daaac@[192.168.2.2]>

Eric,

By intelligent I mean the ability to talk apples to apples.

We have not been doing that, and based on your description of how you
count the steps of a step wedge I now understand why. If I were
counting everything but absolute Dmax I too would be reporting am ES
of 2.4 or above.

Sandy

>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 15:49:23 2005

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