Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Bruce Watson <bwyg@...> wrote:
>
> fredfischer77 wrote:
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Bruce Watson <bwyg@> 
wrote:
> > Hi Bruce
> >
> > I believe grainier highlights are a product of development. Highlight areas tend to 
exhaust or have slower development activity, because of the large amount of exposure 
they receive, creating a larger "grain" where as shadow areas develop more fully. This 
really holds true 
> > with "silver solvent" developers like D76.
> >   
> 
> Interesting theory which holds some truth if you are talking about stand 
> or semi-stand development where the point is to induce developer 
> exhaustion in the highlights. For normal agitation however development 
> doesn't exhaust anywhere on the film. That is actually the point of 
> normal agitation -- to prevent developer exhaustion.
> 
> Grain clumps vary widely in size depending on exposure and subsequent 
> development. One of the reasons for this is the 3D nature of the 
> emulsion. More exposure means that photons transit deeper into the 
> emulsion. When developed to metallic silver, the individual grains 
> overlap forming a larger overall grain clump. If you want to see some 
> photomicrograms, have a look here:
> 
> http://aic.stanford.edu/sg/emg/library/pdf/vitale/2006-03-vitale-
filmgrain_resolution.pdf
> 
> Mr. Vitale has been researching this and other film topics for decades. 
> There's way more information here than most people want to know. But it 
> all makes sense, and other researchers like Kodak's Grant Haist back him 
> up.
> 
> I specifically refer you to page 17, figure 18-D which shows an 
> excellent example of grain clumping.
> --
> Bruce Watson
>


Continuous processing (Jobo, Wing-Lynch, roller transport) has somewhat the same 
"grainer highlight" effect as the soluble halides, which are released in development, act as 
restrainers, again slowing highlight development, and also the shorter development times 
of that type of process. Hand process, dip and dunk all have a "stand" time just for 
restraining reasons. Different B&W films have different amounts of iodides/bromides 
(restrainers) built into them as a control.
I have noticed that film developed in Rodinal seems to have fairly uniformed grain size 
regardless of exposure. Again this is a different developer (p-Aminophenol) that makes a 
very sharp, high acutance image. The high dilution (1:25, 1:50) exhaust quickly in 
highlight areas during the recommended stand times acting as restraint. 
I will refer you to "Photographic Materials and Processes"  page 273 (7.40) which has 4 
authors, and, although I could give a educated guess to who wrote what, the book is 
strong enough to stand on its own.

F Fischer