Any 'acutance enhancing agents' besides potassium iodide?

Athiril · Feb 19, 2015

The images were upscaled 200% digitally, just so it's easier to see.

I can't really make anything out past element 3 on that specific part of the chart, and am tempted to say 2.5 Where as there is still some differentiation at element 5 on the bottom chart. While 3 becomes very clear. I think that's probably the biggest area of difference on the chart, the vertical and diagonals show improvement, though not as huge as the top chart isn't as poor in the those areas in this specific case.

It's the same for me if I look at the chart at 100%, try this link then clicking on the actual image once with the cursor once it's loaded to view it at 100%
http://i.imgur.com/LYteqhR.jpg

Photo Engineer · Feb 19, 2015

Dan, it is the density difference and the contrast difference that can fool you.

Until they are matched I just cannot choose based on prior experience.

PE

Athiril · Feb 19, 2015

I'm not seeing any such difference. Can you point it out?

Photo Engineer · Feb 19, 2015

The "black" bar, dead center top is less dense in one than the other implying different density and / or contrast.

PE

Athiril · Feb 19, 2015

The black bars in the center make up the bottom of the top chart and the top of the bottom chart. They are different parts of each respective image. Compare them to the same area in each. Ie: to the top of the top chart and bottom of the bottom chart.

There's magic tape and or reflection off that section of the chart so the black is lighter than the bottom and sides. Just like on the left side you can see where half goes lighter on both.

Ian Grant · Feb 20, 2015

Crawley wrote his original set of articles in 1960, there was a major step forward in film emulsions in the late 60's with the introduction of FP4 & HP4 and he later wrote that iodide had little of no effect with most modern films.

Kodak films became more susceptible to Dichroic fogging with Thiocyanate as their emulsions were improved, which led to the switch from Kodatol (DK-20) to Microdol and later Microdol-X. Kodak's emulsions varied slightly depending on where they were made & coated, (US, Canada & UK). particularly Tri-X, it may have also affected the susceptibility to Dichrioc fog as Microdol X was introduced much later in the UK.

When I tried a developer that was essentially a hybrid of D25/Microdol so D23 with Sodium Chloride and some Metabisulphite with Tmax100 I was told I'd have Dichroic fog in fact the negatives were fine. The problem is books etc warn of Dicrioc fogging with some older formulae but that was with the film emulsions of that era.

The addition of Thiocyante to Rodinal gives the finer grain you'd expect, what was the drop in effective film speed ?

Ian

Athiril · Feb 20, 2015

I don't think I had much of a drop in speed unlike with sodium chloride, but I would have to actually test for that specifically. Same with Xtol, T-Max had no dichroic fogging in either Rodinal or Xtol with the thiocyanate, FP4+ and 80S did, but the negatives were very good once it was wiped off the film.

I've tested many many strips getting this far with different variables. I suspect this is what Spur HRX is employing in it's developer, and am trying to get my hands on some to see if it produces any better or worse than my results with my equipment and testing setup.

Alan Johnson · Feb 20, 2015

Dan,
First, thank you for presenting these results, it seems a good method not used before on film.
My question -are you looking at resolution rather than sharpness?
Eg, if you photograph the chart on 3200 and 100 ISO film, the 100 will have higher resolution because the grain is smaller.
With about 1g/L thiocyanate, the grain size is reduced due to the solvent effect, the resolution will be higher because the grain is smaller.

David Lyga · Feb 20, 2015

Athiril: PE is correct here. It is amazing how much lower the grain gets when the contrast index is even slightly lowered. Still, there might be at least some validity to your assetion but, do not be misled. - David Lyga

Rudeofus · Feb 20, 2015

Athiril said:
I've tested many many strips getting this far with different variables. I suspect this is what Spur HRX is employing in it's developer, and am trying to get my hands on some to see if it produces any better or worse than my results with my equipment and testing setup.

AFAIK this SPUR HRX developer doesn't use p-Aminophenol, so there are good chances it performs quite a bit better (in all three aspects speed/grain/sharpness) than Rodinal, even with the extra ingredients.

Photo Engineer · Feb 20, 2015

Ian is correct. We have echoed the same comments on Iodide and Crawley developers with modern films.

In addition, a lot of work went into eliminating dichroic fog in films at Kodak.

We (here in Rochester) are working on a number of sulfur sensitization variations at GEH for future workshops. Among other things is the effect that David points out, and so we have to get H&D curves that match so as to make any sense of speed, fog, grain and sharpness.

PE

Athiril · Feb 20, 2015

Alan Johnson said:
Dan,
First, thank you for presenting these results, it seems a good method not used before on film.
My question -are you looking at resolution rather than sharpness?
Eg, if you photograph the chart on 3200 and 100 ISO film, the 100 will have higher resolution because the grain is smaller.
With about 1g/L thiocyanate, the grain size is reduced due to the solvent effect, the resolution will be higher because the grain is smaller.

Yes maximum resolution increases, but at the same time the clarity and contrast of it goes up, eg if the before shot only can really see up to element 3, and that's a just barely can see some kind of fuzzy soft differentiation of the lines, it becomes clear on the after shot, which says to me sharpness at that frequency should be up.

I've also got some FP4+ stand developed in Rodinal 1+100 at EI 500 with the additives, resolution is higher than box speed in Rodinal, and also higher than in Xtol, but with also rougher grain.

On the Delta 3200, only grain improved (tested in Xtol with and without the additives), resolution stayed the same, but I only tested the same amounts as previously mentioned and that was it, I've tested varying amounts on other films, and think this current amount is a good 'general purpose' starting point.

Rudeofus said:
AFAIK this SPUR HRX developer doesn't use p-Aminophenol, so there are good chances it performs quite a bit better (in all three aspects speed/grain/sharpness) than Rodinal, even with the extra ingredients.

I've also done it with Xtol, and Spur HRX appears to list 4 developing agents in the msds iirc.

David Lyga · Feb 20, 2015

And Athiril, you cannot get around this: If you have a low contrast negative, with but slight grain, when you use a high contrast paper in order to reconstitute the image quality (with proper contrast), you are going to get that grain. In many asjpects, 'grain' and 'contrast' are married to each other. - David Lyga

Rudeofus · Feb 20, 2015

Athiril said:
On the Delta 3200, only grain improved (tested in Xtol with and without the additives), resolution stayed the same, but I only tested the same amounts as previously mentioned and that was it, I've tested varying amounts on other films, and think this current amount is a good 'general purpose' starting point.

Speed tests would be very interesting with Delta 3200 and your modified Xtol, because these SPUR developers seem to have massive difficulties with Delta 3200 and its speed potential ...

Athiril said:
I've also done it with Xtol, and Spur HRX appears to list 4 developing agents in the msds iirc.

Make that number five:

Dimezone-S (listed as "4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone")
Phenidone (listed as "1-Phenyl-3-pyrazolidinone")
Hydroquinone
Metol (listed as "4-Methylaminophenol sulfate")
Hydroquinone Monosulfonate Potassium Salt (listed as "Hydroquinone sulfonic acid (potassium salt)")

They seem to have abandoned this approach, their HRX-3 developer MSDS lists only Dimezone-S and Hydroquinone Monosulfonate Potassium Salt as development agents, although we don't know how complete that listing is.

Rudeofus · Feb 20, 2015

Michael, you could quickly check whether it contains sulfite or not: take a very small sample of this dev, add a strong odorless acid (e.g. Citric Acid), then check/smell whether it emits Sulfur Dioxide.

Athiril · Feb 20, 2015

Might be hard, Adotech II stinks of Ammonia. It also fogs the base ever so slightly which is good for automated film readers that can't handle almost perfectly clear base.

Photo Engineer · Feb 20, 2015

Many old formulas contained Ammonia which is a powerful silver halide solvent, but also causes dichroic fog in some cases.

PE

Gerald C Koch · Feb 24, 2015

Acutance developers are based on a mechanism whereby either a single developing agent (like Metol or catechol) or the alkali are deplenished during the development process. This local exhaustion limits the developed image to the surface of the emulsion. Therefore there is less light scatter during printing resulting in a sharper image. One cannot simply add iodide to any developer and convert it into an acutance developer. Nor is there any another magical additive. It is more involved than that.

Photo Engineer · Feb 25, 2015

Well, add to that list the production of a chemical during development that either enhances or retards development, but is not necessarily deplenished during the development. Bromide is an example. It increases locally faster than it can diffuse and the overall concentration goes up. Iodide, under discussion here, is another.

PE

Gerald C Koch · Feb 25, 2015

Alan Johnson said:
In "Controls in Black and White Photography" p234 ,R. Henry discusses the effect of potassium iodide addition to D-76 1+1 and Panatomic-X.Using a microdensitometer he found iodide addition made no difference to the acutance or the height of the border effect.He used 5ml/L of 0.001% iodide.
Not all Henry's results are in line with later opinion,for instance he found diluting Microdol-X had little affect on acutance.

Thank you for citing Dr Henry's excellent book. When I first obtained it I thoroughly read it cover to cover. Sadly that was quite a few years ago but I remembered having read that KI had little or no effect on high solvent developers like D-76. That was the basis of my statement that KI was not a magical additive for all developers.

Jerry

Athiril · Feb 26, 2015

I got my hands on some Panatomic-X (not the aerial kind), and no matter how I developed it, could not exceed 40 lp/mm, which I found odd, the additives iirc had no effect on it, I forgot about it for a bit and put it to the side. If the statement is based on Panatomic-X then I would throw doubt on it as a general rule for this reason.

Alan Johnson · Feb 26, 2015

The suggestion mentioned by Crawley is that iodide in modern films makes them less susceptible to sharpness increase caused by iodide added at 0.00005g/L.
Since IDK the iodide content of Panatomic-X, Henry's result cannot really be claimed to support this, although the iodide was the same 0.00005g/L.
The results of Athiril seem to be new as they are based on an iodide addition some 200 times higher, 0.01g/L

Photo Engineer · Feb 26, 2015

Iodide addition does not work on high iodide films. If Kodak changed the iodide content of an emulsion to get more speed, then the Crawley effect would go down or vanish.

PE

Alan Johnson · Feb 26, 2015

"In a manner akin to a home-based inventor of the Victorian era, Geoffrey went on to create a black and white film developer called Acutol." :
http://www.theguardian.com/technology/2010/nov/15/geoffrey-crawley-obituary

Alan Johnson · Feb 28, 2015

Photo Engineer said:
Iodide addition does not work on high iodide films. If Kodak changed the iodide content of an emulsion to get more speed, then the Crawley effect would go down or vanish.

PE

This may be true but at a level 200 times that previously tested there is no scientific evidence?

Any 'acutance enhancing agents' besides potassium iodide?

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