Re: Best CI for process

A negative with a DR of 3.0, let's say one that has a B+F of log .30
and a highlight reading of 3.30, must by necessity have a CI of over
1.45. The problem is that there are very few films, if any, that can
be developed to a CI of 1.45. Most films are not even capable of a CI
of as much as 1.2. Once they reach a CI of 1.2 any further time in
the developer simply increases density equally on all parts of the
curve, from the shadows to the highlights, but it does not increase
CI. In other words, you may develop longer and push the highlight
density to log 4.0 or above, but any density over that reached at the
point of maximum CI is just garbage density. You might as well take a
piece of opaque plastic and insert it between the light source and
the sensitized paper.

Choice of developer, whether staining or not, is basically irrelevant
as a factor with regard to the maximum potential CI of a film since
this is quality is pretty much built into the film. Of course, if you
use a very energetic formula you will reach the maximum CI sooner in
development, but it is not possible to push the envelope.

Since this discussion emerged from a discussion on developing for
shadow density with in camera negatives I assume that the subject
continues to be this type of negative, as opposed to enlarged digital
negatives or negatives enlarged on lith film. In those cases it may
be possible to reach a CI of 1.45 or higher.

However, assuming that the subject is in camera film, and sheet film
also since we are talking about contact printing in palladium or
platinum, the question remains, which modern films are capable of
being developed to a CI of 1.45?

Sandy

Etienne wrote:

>Sandy wrote:
>
>> So let me ask again. What film/developer/agitation/temperature
>> combination should one use for N development of in- camera negatives
>> when the density range required for scenes of normal contrast is log
>> 3.0 or above?
>>
>> And what should one do when the scene requires N+ development?
>>
>> My best estimate for most common films is that you can't get there from
>>here.
>
>I don't understand the question. The DR of the negative that just "fits" a
>given printing process doesn't change with the scene contrast -- it is a
>matter of (1) FB+F plus the image density necessary to get up off the toe,
>and (2) the Dmax of the film at the shoulder. Neglecting the small rise in
>FB+F that accompanies longer development, one just develops until the
>highlight densities are log D 3.3 or whatever.
>
>Note that users of staining developers may find that the increase in FB+F
>is NOT negligible. (Ditto constant-agitation developing, but to a lesser
>degree.) M-Q or P-Q developers, or even the non-staining pyro formulae,
>used with intermittent agitation, do not have this problem. I develop in
>glycin, which is perhaps the least fog-prone developing agent known, and
>have never had any problem, even using constant agitation for 30+ minutes
>at 75 degrees F. [Side note: beware of any glycin you receive that is
>darker than a sheet of Crane's Ecru paper -- although many internet sources
>say it works fine, IME it does not. It should be just barely off-white.
>I'm speaking from extensive experience here -- I suspect I've mixed more
>glycin developer since commercial glycin developers have been off the
>market than the next 10 glycin users combined.]
>
>If one's film and/or developer will not produce the required highlight
>density (or will not produce it without excessive FB+F), there is still
>hope. Super-proportional intensification (if the shadows are already at
>the correct density and the highlights are insufficiently dense) or
>super-proportional reduction (if you expose more to get the highlight
>densities up where they belong and the shadow densities are too high), or
>both, can expand DR by log D 1.0 or so. I have even made HP5+ negatives
>with a DR of 3.0 this way, although I don't care for the film and stopped
>testing.
>
>Best regards,
>
>etienne
Received on Sat Oct 1 08:12:37 2005