Plus X and Tri-X 320 Curves

braxus · Apr 16, 2023

Matt was saying Plus X has a very similar look to Tri-X 320. I shoot Plus X outdoors on sunny days with great results. I dont know if the Tri-X 320 film would give the same effect? Here are the curves between these two films. Im no expert on reading these charts, so maybe someone could comment?

ic-racer · Apr 16, 2023

Those curves were made at the Kodak lab. Yours will likely be different. I usually get my 'look' to an image during printing.

BradS · Apr 16, 2023

I guess it depends on what is meant by "very similar look" and, as @ic-racer says, it depends very much on how you expose and process and print. The characteristic responses of these two are quite different. Certainly, the two films are significantly different in terms of contrast. The characteristic curves plainly show that.

With considerable skill and care, one might be able to get similar looking prints from the two films but, in my experience, it would not be easy at all - especially outdoors in bright, contrasty sun. Kodak's own data sheet indicate that Kodak 320TXP is a fairly difficult film to use in high contrast daylight situations. If you read the text, I belive it says something about 320TXP being optimized for controlled studio lighting.

So, in summary, can it be done? can one get "the same look"? yeah, maybe but it's not gonna be easy.

braxus · Apr 16, 2023

Ok thanks guys. I was hoping the Tri-X 320 would be a good replacement for Plus X. I guess not.

MattKing · Apr 16, 2023

In our off-thread conversations, braxus and I were discussing how he liked how Plus-X responded for him in sunlit conditions, so I referenced how Plus-X had some similarities with Tri-X 320 in respect to shadow separation. My sense is that braxus has a particular interest in that part of the characteristic curve. The suggestion from me that he try Tri-X 320 comes from that fact, as well as my experience with Plus-X that indicated it used to work well too in a studio lighting situation.
I don't know that Tri-X 320 will work for him, but I think it would be worthwhile trying it.

ic-racer · Apr 16, 2023

I have noticed as more and more people constructing and sharing H&D curves. They frequently look different from the curves presented by the manufacturer.

albada · Apr 17, 2023

ic-racer said:
I have noticed as more and more people constructing and sharing H&D curves. They frequently look different from the curves presented by the manufacturer.

Hopefully more and more people are buying this densitometer from our own @dkonigs :
Printalyzer Densitometer

Lachlan Young · Apr 17, 2023

ic-racer said:
I have noticed as more and more people constructing and sharing H&D curves. They frequently look different from the curves presented by the manufacturer.

For the hopefully obvious reason that most home-made H&D curves are not made to the same baseline levels of control and consistency as the average product researcher will have access to as a matter of course. More often than not, the home denistometrists are demarcating their errors without noticing them and/ or not normalising their scales to align with manufacturers' charts they wish to compare.

Not that a short toe GP film like 135 PX (or the last generation 120 version as well) is difficult to find a curve equivalent for from amongst in-production emulsions...

DREW WILEY · Apr 22, 2023

Tri-X 320 is different from Tri-X 400, and is classified as a medium-toe film. Plus X was classified as an "all toe" film, with a long upswept curve, engineered for high-key studio portraiture. The curves are significantly different in that respect. Grain structure is quite different too, Plus-X being much finer grained, and lower speed of course. I guess one could beat them half to death into looking somewhat similar; but perusal of any contemporaneous Kodak black and white film guidebook would spell out a bold distinction between these two films.

A better strategy would be to take a general-purpose med speed film like FP4 and induce a sag in the curve using 1:2 dilution D76. That should come fairly close, unless over-developed.

Lachlan Young · Apr 27, 2023

DREW WILEY said:
Plus X was classified as an "all toe" film, with a long upswept curve, engineered for high-key studio portraiture.

'Plus-X' meant many different things - the OP is referring to 125PX (successor to 135 Plus-X (5062)/ 120 Verichrome Pan), what you're referring to are the characteristics of 4147 in things like DK-50/ HC110 (however in D-76/ Microdol-X, 4147 was designed to deliver short toe/ long straight line characteristics).

DREW WILEY · Apr 27, 2023

Yeah, it's always confusing when the names get re-applied to different products. Verichrome and Vericolor also had more than one meaning. Even Tri-X suffered that fate. I didn't know D76 produced a straight line with anything, generally a bit of sagm more than HC-110 typically. I don't have time to dig thru all the old literature. But the last Kodak guidebook with all the old classic films in it dates from '76, and shows the same long-swept toe curve for both 2147 and 4147 (one set of curves only, for both), based on HC-110. Only Royal Pan had a longer toe. It's been darn near that long since I last used Plus-X Pan myself, and then only in sheets. And it's always been my hunch that Pan Masking Film was basically Plus-X minus the anti-halation layer.

john_s · Apr 28, 2023

Lachlan Young said:
For the hopefully obvious reason that most home-made H&D curves are not made to the same baseline levels of control and consistency as the average product researcher will have access to as a matter of course. More often than not, the home denistometrists are demarcating their errors without noticing them and/ or not normalising their scales to align with manufacturers' charts they wish to compare.

Not that a short toe GP film like 135 PX (or the last generation 120 version as well) is difficult to find a curve equivalent for from amongst in-production emulsions...

My curves are of course not as accurate as those of the manufacturers, because I do them with in-camera tests, and can't allow for flare and some shutter inaccuracy and some various other things. However, in a way, they are superior for my purposes because they are directly transferable to my use of the materials, my developing choices etc. I don't do endless measurements, but when I had to change from Neopan400 to HP5+ I have found my amateurish curves useful.

Juan Valdenebro · Apr 28, 2023

125PX was amazing. I can't really know the level of my skills back then, but in 2003 I compared HP5+, Tri-X400, FP4+ and 125PX, all in ID-11 1+1, same scene, soft light, same contrast negatives, and Plus-X had both the best tone and definition to me, my classmates and my teachers.

albada · Apr 29, 2023

Juan Valdenebro said:
125PX was amazing. I can't really know the level of my skills back then, but in 2003 I compared HP5+, Tri-X400, FP4+ and 125PX, all in ID-11 1+1, same scene, soft light, same contrast negatives, and Plus-X had both the best tone and definition to me, my classmates and my teachers.

What was in that scene? One poster mentioned that the curve for Plus-X was "all toe", and I'm thinking of kinds of scenes that would benefit from that curve.

Mark

DREW WILEY · Apr 29, 2023

Low contrast scenes or studio settings where you want distinct upper midtone and highlight tonality expansion, at the expense of deep shadows. You might also try Pan F Plus, which doesn't have much of a toe at all, but an exaggerated S-curve suited to scenes with about the same limited contrast range as works well for color slide film. That will give you some wonderful silvery upper tones if you know how to use it; but don't expect to be happy with it in high-contrast applications.

Juan Valdenebro · Apr 29, 2023

albada said:
What was in that scene? One poster mentioned that the curve for Plus-X was "all toe", and I'm thinking of kinds of scenes that would benefit from that curve.

Mark

125PX was not all toe: it had good separation in the shadows.
And there's not a single type of scene that's better for it: any photographer can make it work well for low, medium, and high contrast scenes.
My scene had all tones from black to white, soft light outdoors, at EI125 spot metered on Kodak's gray card, ID-11 1+1.

DREW WILEY · Apr 29, 2023

Good separation compared to what? Compared to Super-XX or TMax? - not even in the same league. I wouldn't dream of using it in the high mountains or stark desert conditions. Even FP4 has a hard time with that. You just admitted you were working with SOFT light outdoor conditions. Make a comparison up in the Andes in direct sunlight, where 11 to 12 stop scene illumination ranges are probably common. And I'm not referring to stomping the life out of the scene by excess under or minus or pull development.

You just validated my own contention as well as Kodak's marketing claims : Plus X was designed for softer light or controlled studio conditions.

Juan Valdenebro · Apr 29, 2023

Hi Drew,
Good separation in the shadows in opinion of its Kodak designers.
I don't need more shadow separation than that.
If your opinion is, with the slightly more shadow separation we can get from TMax films, your photographs are better, you have the right to that opinion.
I don't think that way about my photographs.
Take the 20 most important photographs in history, and give them a little more or a little less shadow separation: it doesn't matter at all.

DREW WILEY · Apr 29, 2023

It's not about "just better". There simply won't be anything left in the shadows way down there with a medium toe film unless it's overexposed with the highlights blown out as a result. And I could care less about what someone thinks are the 20 best photos in history. That would be a pitifully tiny and narrow-minded sampling of even a single person's work. It does matter. Otherwise, why would they have even bothered to make such a variety of films to begin with, each with its own personality and commercial users? More detail in the bold graphic shadows of Brett Weston? - end of him in art history. Less detail in AA's shadows - there would go all his collectibility. Even significant musicians carefully tune their instruments. I don't want just something - I want exactly what I want, and nothing less.

When my brother was in a very well known photo academy in the mid-60's, all the students were expected to be proficient in three films - "straigjht line Super-XX for industrial and landscape application, mid-toe Tri-X for photojournalism etc, and long-toe Plus-X for Caucasian studio portraiture. That's because these were very different films, with plenty more to choose from at that time too. And Kodak sold enormous amounts of each of them. T-Max was intended to replace them all, based on its greater development malleability. But it proved too fussy and unfamiliar to many; so those plans only partially succeeded. I've used all kinds of black and white films at one point or another, and am quite aware of the pros and cons of each.

Some people use a single film their entire life until it is no longer made. That's fine. Others like me have needed to use quite a variety of them, including for specialized lab and reproduction purposes. I kept a lot of Tech Pan on hand, for example, for sake or forensic art sleuthing and restoration purposes, which it was superbly designed for prior to modern digital methods. But it was a wretched scenic film. Some people love the gritty street look of Tri-X, and I can admire what they had done with it, but I rarely like it for my own work. Let's just be glad there is still a remaining selection of flavors to choose from in the ice cream shop, and not just one, because they're not in fact all the same.

Lachlan Young · Apr 29, 2023

albada said:
What was in that scene? One poster mentioned that the curve for Plus-X was "all toe", and I'm thinking of kinds of scenes that would benefit from that curve.

'Plus-X' meant different things in different formats, until the last generation that was coated in B38, which was an evolution of the 135 format (and Verichrome Pan 120) version that had a very normal curve shape.

What Drew is referring to is one aspect of 2147 PXE/ 4147 PXT when developed in HC-110. In D-76/ Microdol-X etc, it delivered more normal short toe characteristics.

You can find all the relevant details about PXT in this duplicating manual and in data sheet F8.

DREW WILEY said:
I didn't know D76 produced a straight line with anything

It produces the industry definition of short toe/ straight line characteristics with most general purpose camera films because it was largely the main developer used in designing them.

DREW WILEY · Apr 29, 2023

Or spend a couple decades doing off n'on duplications like I did, and you get a good feel for what films and developers are the most appropriate for any given project. When in doubt, go with something in the mid-range of characteristics, like FP4 these days. Sometimes the big labs would substitute DK50 for HC-110 for sake of cost saving. Good ole D76 has certain bad habits if you don't understand it needs to be used at pH equilibrium. It's the basic Ford/Chevy developer - certainly no Ferrari. And I'd never use it for serious straight line applications like matched color separation negs. HC-110 can be diluted and modified into way more configurations than 76. But now the duplication and restoration trade have gone almost entirely digital. And that's the only application where I optionally use a digital camera myself - at the copy stand. A sneaky little trick I sometimes employ to shorten the toe and make it steeper is to add a tiny amount of 1% benzotriazole to the HC-110, which acts as a "toe cutter".

But, Lachlan, the official published curves I was just viewing a day or two ago were specifically for BOTH 2127 and 4147, and done in 76, and showed a rather long toe. How do you explain that? In fact, it's the same set of curves you linked in the duplicating manual (which I also own). That is a long toe. Period. Just compare it to the Super-XX page. This is all academic of course, since both of those films are now obsolete.

braxus · Apr 29, 2023

I asked this before, but didn't get a response on it. If using DK-50 to get a more Plus X film curve out of the FP4+ film, someone also mentioned HC-110 as a substitute for DK-50 giving similar results. I have some HC-110. Will HC-110 give the same curves as DK-50, or should I just stick with DK-50?

DREW WILEY · Apr 29, 2023

Whichever one is more convenient for you. I wouldn't worry about it too much.

albada · Apr 30, 2023

DREW WILEY said:
A sneaky little trick I sometimes employ to shorten the toe and make it steeper is to add a tiny amount of 1% benzotriazole to the HC-110, which acts as a "toe cutter".

Does that trick work for other developers?

sasah zib · Apr 30, 2023

braxus said:
I asked this before, but didn't get a response on it. If using DK-50 to get a more Plus X film curve out of the FP4+ film, someone also mentioned HC-110 as a substitute for DK-50 giving similar results. I have some HC-110. Will HC-110 give the same curves as DK-50, or should I just stick with DK-50?

my introduction to hc-110 was when a kodak tsr brought a 'new' developer. we mixed/used dk50 & dk60 by the barrel ... that first labsheet showed all three devs with conversion of the 50 &60 to 110...hc could mimic the others for general work. dk60 was better for some masks; 50 for others as well as split seps.

the tsr was calling it high concentrate --

I would not switch to 110, if my prints from 50 satisfied me. i'm quite happy mixing from skratch.

Plus X and Tri-X 320 Curves

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