U of S | Mailing List Archive | alt-photo-process-l | RE: pt/pd stops

RE: pt/pd stops

	I must beg you to forgive and indulge me.  I am 58 years old and,
when I first learned to write and ever since, I was taught to always
capitalize the greeting and farewell in any written material.  You will
notice that I do not use caps in the body (unless the proper name of a
person or thing) of my writing because I was told early on in my digital
education that caps equaled shouting in the body of the e-mail. 
	I guess I will have to ask you to understand that, if I am shouting,
I am addressing you as "dear" (aka cher) and wishing you "cheers" which I
feel is something to shout about!  ;-))
	With PMK I found exactly the opposite.  The acutance of my T-max and
Tri-X images is much higher than with non pyro developers.  But many things
might account for our different findings.  For pt/pd I dev to a D range of
2.7 to 2.9 and the same negs print very nicely at contrast 1 or maybe 1/2 in
the extreme case.  Of course, if you don't use vc papers, this is a moot
	Anyhow, thanks for your feedback.

-----Original Message-----
From: etienne garbaux [mailto:photographeur@nerdshack.com] 
Sent: Monday, April 13, 2009 11:46 PM
To: alt-photo-process-l@usask.ca
Subject: RE: pt/pd stops

Bob (whom I really wish would STOP SHOUTING in his posts) wrote:

>You really should consider Pyro developers if you want negs that 
>print well in both alt processes and silver gelatin.  My 8X10 negs 
>that print wonderfully in palladium with just a little platinum also 
>print very well with a contrast #1 filter with most variable 
>contrast fiber base silver gelatin papers.

If that is true at all, it is only true for multicontrast papers, 
which I do not use.  Further, my guess is that you are not making 3.2 
DR negatives for your Pd/Pt process -- even stained-pyro negatives 
with a total (silver + stain) actinic density range of 3.2 (which 
would typically have a silver-only DR of 2.8-3.0) will not print 
acceptably on MC SG paper with a #1 or even #0 filter.

Finally, as I posted in the past in the course of describing 
extensive testing I did on staining pyro developers:

>I discovered that the resolution of the stain image was lower than the
>silver image, by a fair amount.  A bit of reflection suggested that this
>was due to lateral diffusion of the stain in the gelatin, which I later
>found was known in the literature.  I also found that the stain density was
>directly proportional to the silver density at all total densities under
>the rather wide range of processing variables I tried (with an added
>overall fog density when stain conditions were maximum).
>(Another sidenote:  Because one can achieve HD curves identical to the pyro
>silver + stain curves with other developing agents, I concluded that the
>"look" of pyro is not due to its mass staining properties.  The main
>difference I see is in the edge effects.  One often hears that pyro
>negatives have especially high acutance and edge effects.  This is true of
>the pyro *silver* image, and was a truism in the days of *non-staining*
>developers.  However, the *stain* image with its diffusion contributes a
>softening, "reverse" edge effect.  The resulting edges have both a
>[geographically] very-small-scale edge acutance, and a somewhat-larger-
>scale softening of the edges -- a rather complex look.)

This can be a cool look, but the overall effect is certainly not what 
I would call "high acutance" (or if it is, it is because the stain is 
not contributing much of the actinic density and you have, for 
practical purposes, an un-stained pyro negative).  Rather, I would 
describe the overall edge effect of an image made from a stained-pyro 
negative as a bloom or soft glow.

While I'm taken by the charm of this complex "reverse edge" effect 
for certain images, I'm sick to death of seeing it used for 
everything -- like putting mustard or caramel sauce on everything one 
eats.  And because my personal vision runs to extreme detail, the 
overall loss of resolution due to the stain image is generally not a 
plus for my work.

The fact that the ancient non-staining pyro "high acutance" truism 
survived into the present staining-pyro era is another testament to 
the ability of writers to ignore their eyes and repeat the received wisdom.

Well, enough about pyro.  I don't expect to talk anyone out of it, 
but perhaps someone will look carefully at his or her prints and see 
that -- whatever pyro's virtues -- they are not what many proselytes claim.

Best regards,


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