Digital BW, The Print

----- Original Message -----
From: "Todd Flashner" <tflash@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Sunday, April 07, 2002 1:38 PM
Subject: Re: [Digital BW] Re: Scanning for print size - Pyro


> on 4/7/02 4:19 PM, Martin Wesley wrote:
>
> > The staining occurs in direct proportion to the silver development. You
can
> > actually take a pyro developed neg, bleach all the silver out of it and
> > print from image recorded by the grainless staining process. Practically
> > this does not appear to improve print quality so it isn't done.
>
> So the dense areas get more stain than the thin areas, increasing
contrast?

Todd,

The image formed is a combination of silver grain and stain density which
both respond proportionally to exposure. The contrast is determined by the
development just like any other film and developer combination. A pyro
developed negative would look very thin to you. One of the advantages is
that since the highlights densities are a combination of translucent stain
and silver they do not get block up as soon as non-staining developers do.
The end result in an increase in the usable highlights.

Pyro produces two types of staining action. One in conjunction with silver
development which you want and one as the result of oxidation from air in
the darkroom which can increase overall fog and can be uneven which you
don't. The problems associated with the second pushed it out of favor as new
developers came along. The PMK formula side stepped the bulk of the unwanted
staining. I get really critical and develop in pyro in a nitrogen atmosphere
but that is another story.

Remember that with all developers, increase development to increase
contrast, decrease development to decrease contrast. As you increase
development you do increase fog+base film density but it increases much more
slowly than the highlight density.

Martin