Altering dev times for contrast...any point?

[Robert Canis]

In Large format we have the opportunity to make a custom development for each individual sheet, or we simply group those shots requiring (say) N-1.

We have techniques that are valid for rolls, for example diafine developer is a highly compensating way, or stand...

Also, depending on our particular subject (sunny vs cloudy, kind of scenes in the roll ) we may use something not standard. I've a proficient friend that shot (for 2 decades) TMY ay EI 200 developed N-1, now he shots TMX at box speed developed normally, but he presently shots different subjects...

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Regarding Split Grade, this is mostly the same than non Split grade. An Split Grade printing ends in the same than using a particular grade. At the end after exposing with (say) Grade 2 we also burn highlights with 00 and shadows with 5... Split grade has a single (usually minor) advantage compared to regular: we can dodge some areas in the 00 exposure or in the 5 exposure. After using a particular grade we can allso burn different areas with different grades, but dodging 00 or 5 can only be done in Split.

For the basic adjustment of a print (before image manipulation activity) we vary Exposure and Contrast. In Split Grade we (usually) adjust that in a different way, we adjust the Yellow (green+red) exposure for the highlights and the Purple (blue+red) for the shadows. With regular printing we usually adjust exposure for the highlight and later we adjust grade for the shadows. At the end it's the same, done in different ways. Split Grade provides no miracle, just another workflow, with the minor advantage of a more selective dodging, if we master that.

For myself, I use Rodinal 1:50 but the time and agitation I employ for N development enables me to obtain in excess of the usual 5 stops. Indeed, I would say I get closer to 7 resulting in a negative exhibiting good contrast and minimal grain. The scene has to be pushing beyond this for me to do N-1.



shoot HP5 at box speed

 

[138S]

enables me to obtain in excess of the usual 5 stops. Indeed, I would say I get closer to 7 resulting in a negative exhibiting good contrast and minimal grain.

I depends on film processing, but we can easily get well beyond 7 stops...

Negative film usually offers way more than 5 stops latitude, with POTA developer one may cature up to 20 stops, being 18 quite easy. Another thing is being able to print that dynamic range on paper, or showing it in a monitor. See this color negative film exposure test made under regular development, the girl's face (and hands) has detail at -6 but also at +6, probably at labeled "correct exposure" face was at some +2.5 locally so in the -6 shot the face would be at some -3.5 locally, at +6 image still has good detail so for sure Portra sports more than 12 stops range, before we no pull.

(https://carmencitafilmlab.com/how-exposure-affects-film/)

This is the Kodak Vision 500T graph, contrary to still fim, this stock film datasheet shows latitude in stops:

 

[Lachlan Young]

For myself, I use Rodinal 1:50 but the time and agitation I employ for N development enables me to obtain in excess of the usual 5 stops. Indeed, I would say I get closer to 7 resulting in a negative exhibiting good contrast and minimal grain. The scene has to be pushing beyond this for me to do N-1.



shoot HP5 at box speed

Done correctly, 'Normal' processing should deliver 7 stops of information on the film's straight line at about the right average gradient to print well on grade 2 paper, relative to your enlarger light source etc. Something worth noting about Rodinal and FP4+/ HP5+ is that it tends not to shoulder/ roll off highlight density (likely because of the low solvency not releasing restraining byproducts - iodide etc - from the emulsions), thus meaning that densities beyond those 7 stops will continue to record fairly linearly - this may or may not be useful to you. You may also find that there's a bit less useful shadow speed difference between FP4+ and HP5+ in Rodinal, rather than the 1 2/3 stops the box speeds suggest.

 

[138S]

LOL !!! more iodide/bromide in the emulsion ?= more density. "Again it's someone trying to 'prove' that they're cleverer than the emulsion development photoengineers who designed the film to demonstrate he is cleaverer than them."

When one forgets to take the prescribed pills, or when he takes too many pills, then he starts confusing bromide with other things

 

[Lachlan Young]

It's not just about bromide. Iodide, and the placement/ accessibility thereof are seemingly very important to how the sharpness and highlight behaviour of modern films are regulated. These characteristics have been well known in the literature for decades. Rodinal seemingly does not access the surface iodide as well as moderately solvent developers, thus it delivers overall lower sharpness in absolute measurable terms, and apparently less shouldering/ limiting of the maximum density of an emulsion. The larger granularity it tends to deliver may mislead some to believe it's 'sharper', but when enlarged to reasonably large sizes or scanned with equipment capable of delivering high MTF performance, the loss of fine detail compared with more solvent developers like D-76 becomes apparent. PQ Universal, which is also very low solvency, exhibits similar behaviour, delivering a very long straight line and larger granularity. In other words, it's possible by controlling the distribution of the iodide within a set of emulsions to potentially offer significant differences in behaviour between solvent and non-solvent developers. A film with less surface iodide in the slow emulsion(s) would exhibit less difference between solvent and non solvent developers, but may overall deliver less sharpness than one with surface iodide developed in a solvent developer.

 

[Robert Canis]

I depends on film processing, but we can easily get well beyond 7 stops...

Negative film usually offers way more than 5 stops latitude, with POTA developer one may cature up to 20 stops, being 18 quite easy. Another thing is being able to print that dynamic range on paper, or showing it in a monitor. See this color negative film exposure test made under regular development, the girl's face (and hands) has detail at -6 but also at +6, probably at labeled "correct exposure" face was at some +2.5 locally so in the -6 shot the face would be at some -3.5 locally, at +6 image still has good detail so for sure Portra sports more than 12 stops range, before we no pull.

(https://carmencitafilmlab.com/how-exposure-affects-film/)




View attachment 265450



This is the Kodak Vision 500T graph, contrary to still fim, this stock film datasheet shows latitude in stops:

View attachment 265453

That is impressive!