Using Perceptol ignoring speed loss?

Juan Valdenebro · Mar 6, 2022

I wonder if someone's using Perceptol for box speed and even for mild uprating: a third or two thirds over box speed...
It's known Perceptol is a speed losing developer, but Ilford's official datasheets also give times for box speed for several films: Delta100, PanF50+ and FP4+, and the same for TMX and TMY... At least those five can be decently used at box speed in Perceptol. And there are official Ilford times not only for box speed at 1+3, but at 1+1 and stock too!
I don't use Perceptol for small or absent grain, but for tone and for making grain sharp and organized: HP5+, for instance, has a type of grain I dislike in ID-11/D-76, a mess, but in Perceptol, no matter the used dilution, HP5+ produces beautiful, tight, sharp and equalized grain.
I remember a couple of times I've read it's possible to do slight pushes with Perceptol, and that yet it controls grain and contrast better than ID-11/D-76 because it's a slow working developer. It seems in absence of Hydroquinone, Metol defines a better type of image structure that's visible in prints when we use ISO400 35mm film.
Someone with experience using Perceptol this way?
By now I've seen it works well with HP5+ for soft light at box speed... Soon I'll check EI640.

pentaxuser · Mar 6, 2022

Juan, Ilford even give times for D3200 at 3200 with Perceptol in its Perceptol spec sheets. Here it is: the 18 refers to mins
EI 3200/36 18

So it must work based on the above, surely?

pentaxuser

Lachlan Young · Mar 6, 2022

Juan Valdenebro said:
It seems in absence of Hydroquinone, Metol defines a better type of image structure

Metol's sharpness enhancement seems to be from exhaustion byproducts - adding any HQ (etc) switches this effect off. Phenidones on the other hand seem to produce inhibition effects and don't lose this effect when HQ (etc) is added. Most films are optimised for the behaviour of ID-11/ D-76 where sharpness enhancing inhibition effects are largely derived from its solvency releasing development inhibition agents (I and Br) from the emulsion(s), thus developers that have further sharpness enhancing inhibition agents etc might seem to deliver higher levels of visual granularity. Xtol seems to attempt to square this circle - balancing out speed, sharpness and granularity.

It also seems that the reason Kodak never pursued Rodinal types of developer post-WW2 was because it was felt that Microdol/ Microdol-X (and by extension, Perceptol) were superior in outcomes. As with Rodinal, I wouldn't try to compensate for underexposure with Perceptol, but there's no reason it can't be used for development to a higher contrast index. From Ilford's HP5 (not +) data, the idea of rating at EI320 in stock Perceptol when developing to a 0.7 G-bar is suggested and EI 200 for 0.55. It doesn't take a lot to see where the suggested setting of 250 for 0.62 might have come from. Metering methods will further alter this.

Alan Johnson · Mar 7, 2022

Perceptol 1+3 was a favorite of Barry Thornton in his book Edge of Darkness . He also argued that Metol alone ought to be the sharpest developing agent, IIRC that was before the days of FX-39. Here is Delta 400 at box speed in Perceptol 1+3 with my Epson V700, click twice and wait for it to load.
https://www.flickr.com/photos/98816417@N08/50736160741/

snusmumriken · Mar 7, 2022

My uninformed experience of using a metol-only developer - in the shape of Barry Thornton's 2-bath - is that you can make the most of film speed (Ilford's box speeds work well for me) by extending development in a very mild alkali (the first bath in the 2-bath formula) but that pushing your luck in this respect results in high fog levels (i.e. development starts in grains that weren't actually exposed), which impacts on tonal rendering. I don't know how this would translate to the use of a 1-bath developer. Basically you are expecting to under-expose and over-develop, without adjusting the chemical environment. I'd have thought that can only produce poor negatives. Someone with more technical knowledge will hopefully improve on my inexpert view!

Alan Johnson · Mar 7, 2022

Perceptol in the undiluted form contains a high concentration of sulfite . This dissolves the exterior of silver bromide grains and re-precipitates the silver uniformly over the surface of the emulsion, giving fine deposits that give the fine grain appearance. The low pH means that the sulfite is in contact with the silver grains for longer and dissolves more, causing a reduction of the effective EI to half box speed.
When diluted 1+3, the dissolution of grains by sulfite is much less and the grain appearance is somewhat larger but sharper. Larger grains are developed corresponding with an increase in the effective speed of the emulsion to box speed.
This is a simplified explanation.

Juan Valdenebro · Mar 7, 2022

pentaxuser said:
Juan, Ilford even give times for D3200 at 3200 with Perceptol in its Perceptol spec sheets. Here it is: the 18 refers to mins
EI 3200/36 18

So it must work based on the above, surely?

pentaxuser

I have not tried it, but I bet beautiful photographs can be made even with D3200 in Perceptol, depending on scene contrast, and possibly that's why there's an official Ilford time for it.
I like TMZ in TMaxDev.

Juan Valdenebro · Mar 7, 2022

Lachlan Young said:
Metol's sharpness enhancement seems to be from exhaustion byproducts - adding any HQ (etc) switches this effect off. Phenidones on the other hand seem to produce inhibition effects and don't lose this effect when HQ (etc) is added. Most films are optimised for the behaviour of ID-11/ D-76 where sharpness enhancing inhibition effects are largely derived from its solvency releasing development inhibition agents (I and Br) from the emulsion(s), thus developers that have further sharpness enhancing inhibition agents etc might seem to deliver higher levels of visual granularity. Xtol seems to attempt to square this circle - balancing out speed, sharpness and granularity.

It also seems that the reason Kodak never pursued Rodinal types of developer post-WW2 was because it was felt that Microdol/ Microdol-X (and by extension, Perceptol) were superior in outcomes. As with Rodinal, I wouldn't try to compensate for underexposure with Perceptol, but there's no reason it can't be used for development to a higher contrast index. From Ilford's HP5 (not +) data, the idea of rating at EI320 in stock Perceptol when developing to a 0.7 G-bar is suggested and EI 200 for 0.55. It doesn't take a lot to see where the suggested setting of 250 for 0.62 might have come from. Metering methods will further alter this.

Good post, Lachlan, thanks.
I'm planning this use of Perceptol for -as you said- development to a higher contrast index, thinking of overcast light only, as I carry a second camera for direct sunlight unless I'm exposing at half box speed with my main camera so I can use it well for sun too.
Yesterday I read someone saying he uses Perceptol for ISO400 at EI1600! I bet Perceptol will do a good job et EI640 even if grain grows a bit: I like that very much, as long as the image retains Perceptol's grain: more organized and stable than HP5+ grain in D-76. What I decided today was to use a dilution that's stronger than 1+3 for mild uprating. 1+3 is a little weak.
Have a nice day.

Juan Valdenebro · Mar 7, 2022

Alan Johnson said:
Perceptol 1+3 was a favorite of Barry Thornton in his book Edge of Darkness . He also argued that Metol alone ought to be the sharpest developing agent, IIRC that was before the days of FX-39. Here is Delta 400 at box speed in Perceptol 1+3 with my Epson V700, click twice and wait for it to load.
https://www.flickr.com/photos/98816417@N08/50736160741/

That's great, Alan!
I have never tried D400!
Beautiful!
Thank you!!!

Juan Valdenebro · Mar 7, 2022

snusmumriken said:
My uninformed experience of using a metol-only developer - in the shape of Barry Thornton's 2-bath - is that you can make the most of film speed (Ilford's box speeds work well for me) by extending development in a very mild alkali (the first bath in the 2-bath formula) but that pushing your luck in this respect results in high fog levels (i.e. development starts in grains that weren't actually exposed), which impacts on tonal rendering. I don't know how this would translate to the use of a 1-bath developer. Basically you are expecting to under-expose and over-develop, without adjusting the chemical environment. I'd have thought that can only produce poor negatives. Someone with more technical knowledge will hopefully improve on my inexpert view!

Only in case of high contrast scenes.
For low contrast scenes, sometimes it's not even considered a push, but correct exposure and development.

Juan Valdenebro · Mar 7, 2022

Alan Johnson said:
Perceptol in the undiluted form contains a high concentration of sulfite . This dissolves the exterior of silver bromide grains and re-precipitates the silver uniformly over the surface of the emulsion, giving fine deposits that give the fine grain appearance. The low pH means that the sulfite is in contact with the silver grains for longer and dissolves more, causing a reduction of the effective EI to half box speed.
When diluted 1+3, the dissolution of grains by sulfite is much less and the grain appearance is somewhat larger but sharper. Larger grains are developed corresponding with an increase in the effective speed of the emulsion to box speed.
This is a simplified explanation.

Good text, Alan.
In recent years I've found Metol only developers THE developers. Grain is superb, and tone is superb.
Then we gain speed sometimes, and sometimes we have better keeping properties, but we lose other things sometimes with the rest of developers.
Even if I love D-76, it's just a middle point between Perceptol and Microphen.
Those three (classic Ilford Powder Developers) cover most photographic requirements.

DREW WILEY · Mar 7, 2022

I shoot TMax 100 at box speed of 100 for Perceptol 1:3. It's the only film I use this developer for, at least in this dilution. In the past, I developed a lot of FP4 sheet film in Perceptol 1:1, but needed to rate it at 50 for best results. For some of my other favorite films, like TMY400, FP4+, HP5, and Acros, I now strictly use PMK pyro.

Juan Valdenebro · Mar 7, 2022

My plan for next week (hope the film's here by then) is HP5+@500 in Perceptol 1+2. I imagine 1+3 would probably be a little soft for overcast, considering the native contrast of HP5+.
I want sharp and very visible grain, so I won't go for 1+1, and I seek more contrast for soft light than HP5+ in D-76. For a condenser enlarger, it will be a highish EI for HP5+ in Perceptol, possibly close to a 1 or 1 1/2 stop push.
1+2 is closer to 1+3 than to 1+1. I'll use 200ml of perceptol no matter the format.
And I wonder how that grain will compare to my current test of FP4+ in Microphen.

Juan Valdenebro · Mar 7, 2022

Does anybody know why Ilford's recommendation of a single precise EI for HP5+ in Perceptol (EI250 for stock, EI320 for 1+1 and for 1+3), while for FP4+ they have times for all dilutions at EI50, and also for all dilutions at EI125?

Juan Valdenebro · Mar 7, 2022

Could it be because of FP4's more separated shadows?

DREW WILEY · Mar 7, 2022

Yes, FP4 does extend the straight line deeper into the shadows than HP5. But in this case, the Ilford development recommendation is probably due to their overly optimistic film speed marketing. HP5 does have a longer toe. But there's no way you're going to get a high contrast subject onto the straight line section of the FP4 curve at box speed either. One more reason I don't like standardized contrast index formulas and so forth. I don't want a generic extrapolation of the curve for marketing niche purposes, but want to understand the specific actual curve shape with given developers, especially where the toe begins, because that's where shadow gradation begins to level out.

Another possible reason is that Ilford wants to cover the potential needs of journalistic and street photographers, who often have to "wing-it" just to get results, and are not always demanding of optimal image quality like a large format landscape photographer might be, for example. Some people love HP5 for 35mm street snapshooting, while I refuse to shoot it in anything smaller than 8x10 sheet film due to a much different standard of expectation. Same reason I don't shoot FP4 even at box speed unless its a moderate or low contrast situation. I'd imagine HP5 would come out rather grossly grain in Perceptol 1:3. I love it in pyro, however, for the remarkable "watercolor grain" effect - well blended inconspicuous grain, yet with superb edge acutance.

Juan Valdenebro · Mar 7, 2022

All your points make sense, Drew.
I'll see if I like the grain of HP5+ using 1+2, and if contrast is fine for overcast. And if not, I'll go for 1+1.
Thanks.

Lachlan Young · Mar 7, 2022

Alan Johnson said:
He also argued that Metol alone ought to be the sharpest developing agent

This might have been the case before much research was done into the Phenidones, but it was decades out of date by when Thornton was writing - he might have been correct-ish before the 1950s, but by the 70s/80s, he was out of date, let alone the late 1990s. If someone had the time for some lengthy textual analysis, they could probably work out exactly what books Thornton was relying on - my reckoning is that much was pre-1960, possibly pre-1950. Phenidone far outperforms Metol for sharpness (inhibition vs exhaustion effects), but has major visually obvious disadvantages when used as the sole developing agent, likely because of the inhibiting effects of its byproducts. Upshot is that a PQ developer can be adjusted to at least equal a metol only developer for sharpness - however, those inhibition effects will generally make the granularity more visible. Just to really mess with people's perceptions further, there's some even more confounding data that seems to show that at the concentrations of Metol found at anywhere from stock to 1+3 dilutions of Perceptol/ Microdol type developers, edge sharpness (even with 1970s or older emulsions) is remarkably constant at anywhere from 25-100g/l of sulphite - so all that's likely to be happening is you're largely changing the level of visible granularity rather than altering edge sharpness per se. There's similar data that would appear to support why Xtol has the level of sulphite it does - again because the edge sharpness levels seem to remain steady at stock and various dilutions. What we are told are the thresholds for 'solvency' seem to have become rapidly less clear by the 1950s, and are very blurred today - especially as many emulsions are apparently engineered to interact with developer solvency in terms of exploiting development inhibition effects (from the release of precisely placed iodide in particular). And lower granularity will impact on perceived tonal range (as opposed to sensitometric) in terms of apparent information capacity.

Lachlan Young · Mar 7, 2022

Juan Valdenebro said:
I imagine 1+3 would probably be a little soft for overcast, considering the native contrast of HP5+.

You might just be standing there developing for a while - and the native contrast of HP5+ is little different from Tri-X in D-76 and D-76 derivatives (ie the other Ilford powder developers for example), if you respect the slight difference in effective shadow speed.

Juan Valdenebro said:
Does anybody know why Ilford's recommendation of a single precise EI for HP5+ in Perceptol (EI250 for stock, EI320 for 1+1 and for 1+3), while for FP4+ they have times for all dilutions at EI50, and also for all dilutions at EI125?

Because their opinions will have changed depending on how they perceive the end user exposing HP5+, how they'll process it & what they'll enlarge with. I've seen suggested EI's encompassing EI 200, 250, 320 and 400 in official Ilford documents for HP5+ and Perceptol. The main thing that I think they want to make clear is that it's probably best to not underexpose HP5+ if you want to run it in Perceptol - or at least that there's less latitude for doing so compared to ID-11, let alone Microphen. FP4+ for whatever reasons delivers right at the upper end of its speed rating in D-76 type developers (not in HC-110 - which is littered with atypical results for many emulsions, which are then claimed as incontrovertible universal 'fact' without meaningful comparison) and it is going to have a different iodide level (and possibly placement) from HP5+ - which may impact on relationships with developer solvency & thus development inhibitory effects.

snusmumriken · Mar 8, 2022

Lachlan Young said:
This might have been the case before much research was done into the Phenidones, but it was decades out of date by when Thornton was writing - he might have been correct-ish before the 1950s, but by the 70s/80s, he was out of date, let alone the late 1990s. If someone had the time for some lengthy textual analysis, they could probably work out exactly what books Thornton was relying on - my reckoning is that much was pre-1960, possibly pre-1950.

Lachlan, a problem for most of us is that advances in knowledge are (or were? do they still happen?) reported in academic publications that lie behind a wickedly expensive pay-wall. Of course there is a huge amount of information and/or opinion on the internet, particularly this forum, but it's like trying to piece together several different versions of the Apocrypha. Is there any more up-to-date textbook you would recommend? Or are most advances in photochemistry industrial secrets?

Juan Valdenebro · Mar 8, 2022

More than any other thing, IMO most people don't test materials.
The majority of film users are just reading internet opinions and scanning.
That way it's not possible to see clearly what light sensitive materials were designed for.

Christiaan Phleger · Mar 9, 2022

Juan, in following your (recent) photographic developing journey, I have to add that you may want to try a bit of FX-1 for the grain appearance. A few years ago I was shooting a project and while I did have to work with the more limited tonal scale, the grain and edge effects was closer to what I was looking for. I was shooting a Leica M with a 135mm at f/11, shooting very detailed storefronts with lots of fine detail I wanted to render very crisp, shooting quickly with a light tripod and cable release.

Juan Valdenebro · Mar 9, 2022

Hi Riding,
Thank you!
I'll take a look at it...

flavio81 · Mar 10, 2022

Wow, great thread, thank you very much to the contributors. I hope someday i get hold of a bit of Perceptol to test it.

Using Perceptol ignoring speed loss?

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