Acros II - What speed are you getting?

[Steven Lee]

That is why, if you are asking a question about what "speed" people are getting from a film, it is useful to both determine how they are evaluating that speed and, if they are actually sharing the Exposure Index that they use, what sort of negatives they prefer.

You re-stated the obvious that film speed and EI are different things, and then came to the wrong conclusion. When I'm asking if one is getting full film speed, that's precisely what I am asking. I am not asking them how they usually expose it. Personal exposure preferences should be out of scope. EI does not apply here. Dragging it into a conversation instantly makes it pointless.

Film speed is ISO speed. The purpose of it to have no other. Everything else is just someone's favorite exposure index, including the ZS shenanigans. People say things like "I'm getting full box speed of film X in developer Y" all the time. And everyone understands what they mean.

Your advice above invites people to derail future film speed conversations with an irrelevant tangent.

 

[Stephen Benskin]

You re-stated the obvious that film speed and EI are different things, and then came to the wrong conclusion. When I'm asking if one is getting full film speed, that's precisely what I am asking. I am not asking them how they usually expose it. Personal exposure preferences should be out of scope. EI does not apply here. Dragging it into a conversation instantly makes it pointless.

Film speed is ISO speed. The purpose of it to have no other. Everything else is just someone's favorite exposure index, including the ZS shenanigans. People say things like "I'm getting full box speed of film X in developer Y" all the time. And everyone understands what they mean.

Your advice above invites people to derail future film speed conversations with an irrelevant tangent.

I mostly agree, but believe you are directing your post at the wrong person(s). I also believe people's understanding of the difference between film speed and exposure is not as obvious as you think. My experience is that most of the discussions on film speed get derailed because of it. It's either that or they are using one or more logical fallacies.

 

[chuckroast]

You re-stated the obvious that film speed and EI are different things, and then came to the wrong conclusion. When I'm asking if one is getting full film speed, that's precisely what I am asking. I am not asking them how they usually expose it. Personal exposure preferences should be out of scope. EI does not apply here. Dragging it into a conversation instantly makes it pointless.

Film speed is ISO speed. The purpose of it to have no other. Everything else is just someone's favorite exposure index, including the ZS shenanigans. People say things like "I'm getting full box speed of film X in developer Y" all the time. And everyone understands what they mean.

Your advice above invites people to derail future film speed conversations with an irrelevant tangent.

Forgive me, but this makes no sense to me. "ISO Speed" is a laboratory standard. It is intended to bring consistency of measurement across different manufacturers and films. Assuming the manufacturer has done their job properly is IS the laboratory standard speed of the film. That means that everyone gets an ISO of 100 with Acros II. But this is only obliquely related to what any given individual will actually realize in practical use.

So, when someone says "I am getting full box speed", it means that - for their manner of exposing, developing, printing, scanning, etc. - they are getting the same effective speed as the ISO rating.

You cannot ask "is anyone getting full film speed" without also understanding how the photographer is shooting, processing, and displaying their work. The former proceeds from the latter and the question is meaningless if you don't know both.

For example, I routinely get "full box speed" when I semistand develop. In my case, that means I can set the meter to the ISO speed of the film, meter for the darkest shadow of interest, and set the exposure to 2 stops below indicated (Zone III) because that where I want the shadow detail to lie on the HD curve. All of this is just my own convention, not some canonical truth. It is how I shoot and place. You may do so differently to suit your visualization.

As another example, you'll hear people talk about pushing film. But the film hasn't gotten any faster, it's not more light sensitive. That is, the ISO rating isn't increased by film "pushing". What they are saying - whether they acknowledge it or not - it that they are sacrificing shadow detail, and increasing highlight contrast significantly, by doing two things: A) Telling their light meter that the film has an effective speed far above its ISO rating, and B) Overdeveloping aggressively.

So I do think the "what speed are you getting" isn't a particularly useful question unless you also stipulate these other parameters of how you work.

 

[Arvee]

I agree with @chuckroast and perhaps the thread title would have been worded better as "What ASA are you using to achieve the aesthetics you desire in your black and white prints?" thus making film speed assignment purely subjective.

That is the bottom line: using the product and tools in a manner to allow the user to achieve his desired artistic vision while keeping in mind the profile of the film's capability/limitations as outlined in the ISO definition.

Simply put: use whatever ASA you desire that fits the film's capability and also achieves your desired end result and not be constrained by the restrictive nature of the ISO specification.

Black and White Photography, on the whole, is far more an artistic endeavor than documentary.

 

[runswithsizzers]

I also believe people's understanding of the difference between film speed and exposure is not as obvious as you think.

The difference is not obvious to me. I thought the question was, What EI do you use with Acros? Apparently my ignorance is so profound, I should have never posted my first reply (#4), and I would delete it if that were possible.

 

[chuckroast]

The difference is not obvious to me. I thought the question was, What EI do you use with Acros? Apparently my ignorance is so profound, I should have never posted my first reply (#4), and I would delete it if that were possible.

I think you're original understanding is reasonable (and was mine as well). We may now just be in a pedantic rabbit hole ...

 

[Steve Goldstein]

A “pedantic rabbit hole”? On the Internet? Never!

 

[Steven Lee]

Forgive me, but this makes no sense to me. "ISO Speed" is a laboratory standard. It is intended to bring consistency of measurement across different manufacturers and films. Assuming the manufacturer has done their job properly is IS the laboratory standard speed of the film. That means that everyone gets an ISO of 100 with Acros II.

Exactly. This is exactly what I was asking, because not all manufacturers adhere to the ISO standard. Foma 400 never reaches its stated ISO speed even in Microphen, for example. And that is what I was asking: whether Acros offers honest ISO 100 or not, and in what developers.

There was no need to bring exposure into the conversation, as Matt was suggesting. Photrio loves going on tangents in threads, which can be fun at times, but it's not always helpful.

 

[pentaxuser]

The way you answered the question, runwithsizzers, is exactly the way it was asked so you did exactly as was asked. However it was bound to move quickly on to the processing, developers, agitation etc. Sometimes that leads down rabbit holes. This can be both productive and unproductive.

In fact a useful answer to the person asking questions expanded on in the thread has to include each users experience in terms of agitation developer etc with a picture or pictures of such an example as you provided.

pentaxuser

 

[chuckroast]

A “pedantic rabbit hole”? On the Internet? Never!

"I'm shocked, SHOCKED, there's gambling going on. Your winnings sir." -Casablanca

 

[MattKing]

There was no need to bring exposure into the conversation, as Matt was suggesting.

With all due respect, I think you invited that when you started the thread.
And when I read the initial post, I was somewhat surprised that you asked your question the way that you did. That surprise was based on what I've observed in your posts.
Very few people here make use of a densitometer and graph their characteristic curves. I haven't done that for years. I have never owned a densitometer, and would not be likely to buy one, because if and when I need one, I have friends .
In my case,, if someone asks me about a film's speed, I am happy to share with them the information that I can, and I believe it is relevant and can be helpful to those who don't have a densitometer at hand or the ability/knowledge to make full use of the results from them. But it is not the same thing as an analytical speed test.
The vast majority of people here (and in the world) don't evaluate their results based on anything like an ISO standard, because they aren't set up to do so. Instead they make practical determinations of what EI works best for them. Some/many of them conflate speed with EI.
I expect that you were hoping to get responses from people like Stephen and Bill and albireo, who do make use of the tools that do reveal actual speed. But when you couched your question the way that you did - including references to "crushed shadows" - that got you a lot of very different results.
Of course, if you had asked the question the way that I would have expected you to - something akin to "share your curves" - you probably would have had the same responses from chuckroast anyways.

 

[chuckroast]

Exactly. This is exactly what I was asking, because not all manufacturers adhere to the ISO standard. Foma 400 never reaches its stated ISO speed even in Microphen, for example. And that is what I was asking: whether Acros offers honest ISO 100 or not, and in what developers.

There was no need to bring exposure into the conversation, as Matt was suggesting. Photrio loves going on tangents in threads, which can be fun at times, but it's not always helpful.

But that's what threw me off. If a manufacturer claims somethings meets the ISO standard - unless they are lying - then it meets the standard. So Foma 400 is either jolly well is ISO 400 (likely) or Foma are lying (unlikely). There is no such thing as "honest" ISO speed. ISO is just a laboratory standard of measurement.

Whether you an actually achieve that speed in practice is entirely a matter of the type of developer you use and how you develop. As I mentioned earlier up the rabbit hole here, I have yet to see any film hit full ISO speed in practice when using conventional development, but all of them do when developed for a very long time like one does in seminstand at least for my way of placing exposure.

But that's why exposure does enter the picture and why I think Matt makes a fair point. What do you mean by "honest" speed? Formally, you'd have to do the measurements and calculations mentioned above to confirm that Foma are following the ISO standard properly. I sort of doubt that's what you're after. My guess it that you want to know whether or not you can expose the film at the ISO indicated speed and get good results. And "good" here is all about how you expose, place, develop, print and so on.

Precision of language might also help here:

ISO - A laboratory standard for specifying film sensitivity to light

Personal ASA or Personal EI- The film speed I use when calculating exposure to get negatives to produce the results I like

 

[Steven Lee]

@chuckroast Interesting... so you think there's a way to get Fomapan 400 to show true ISO 400 performance with semi-stand development?

I guess you and @MattKing are both correct at pointing out that my language should have been more precise. Next time I'll do better, although I did try to distance it from exposure, knowing Photrio's habits of force-lecturing people on tangentially related topics... From now on my questions here will be written as legal contracts, 2+ pages no less!

 

[MattKing]

@chuckroast Interesting... so you think there's a way to get Fomapan 400 to show true ISO 400 performance with semi-stand development?

I guess you and @MattKing are both correct at pointing out that my language should have been more precise. Next time I'll do better, although I did try to distance it from exposure, knowing Photrio's habits of force-lecturing people on tangentially related topics... From now on my questions here will be written as legal contracts, 2+ pages no less!

Actually Steven, I was interested in the question that I think you meant to ask, and was looking forward to the sort of responses that I think you were looking for.
While I don't do the plots or similar investigations, I do value them. No contracts are necessary .
And correct me if I'm wrong, but I believe that there is information out there that indicates that Fomapan 400 can show ISO 400 if you pick exactly the right developer and bend the ISO testing procedure as far as it can go without breaking it.

 

[Steven Lee]

@MattKing Hehe, basically what happened is that a straightforward/boring question got diverted into a far more nuanced and interesting territory of finding film+chemistry+development combination to suit one's needs. I am certainly now intrigued by stand-developing Fomapan 400. I don't think that there's an off-the-shelf developer that gets me anywhere close to ISO 400 with that film with standard Kodak/Ilford recommended intermittent agitation. But I want to use it more. I have a soft spot for their spectral response (ghost-faced portraits) but never liked their limited range / high contrast and crushed shadows when I expose them at box speed and develop according to datasheets.

[EDIT] Based on what I gathered on Acros, it is indeed slower than true ISO 100 films like FP4 or Delta 100, Chuck's comments notwithstanding. So I got my boring answer too!

 

[chuckroast]

@chuckroast Interesting... so you think there's a way to get Fomapan 400 to show true ISO 400 performance with semi-stand development?

I guess you and @MattKing are both correct at pointing out that my language should have been more precise. Next time I'll do better, although I did try to distance it from exposure, knowing Photrio's habits of force-lecturing people on tangentially related topics... From now on my questions here will be written as legal contracts, 2+ pages no less!

No contract required, just some clarity in what you're asking.

Fomapan 400 would likely show a true usable EI of 400 in seminstand with either D-23 diluted 1:1 up to 1:3 or so, or Pyrocat-HD 1.5:1:200. But that's not the whole story.

First, you have to deal with proper film suspension to avoid nasty drag effects.

Then, there is the question of whether it will give you the look you want. Dilute D-23 can reveal grain more than you might like, depending on format. I've no idea how it would do with Fomapan 400. Pyrocat-HD can give you a great look but - again - it takes time to dial it in right. How you meter and place things figures prominently here as well.

I've had very good outcomes with extended, low agitation development, but it took a bit of work to dial it in. If you only goal is try and make the film really work at full box speed, I'm not sure that alone makes it worth it.

 

[chuckroast]

@MattKing But I want to use it more. I have a soft spot for their spectral response (ghost-faced portraits) but never liked their limited range / high contrast and crushed shadows when I expose them at box speed and develop according to datasheets.

So, just for fun, try exposing it at 200 and underdeveloping 20% against recommendation and see how that looks.

 

[Steven Lee]

@chuckroast Thank you for your responses, Sir. That's not where I wanted this to go, but I'm glad it did.

 

[faberryman]

It also would help to know what developer Foma chose and what developing regime they followed in conducting their ISO testing.

 

[Stephen Benskin]

Hope you don't mind, but I played a little with your image and it appears shadow detail isn't all that bad. The image just appears to have been printed heavy. The negative should have even more and would be a better way to evaluate the exposure.

"ISO Speed" is a laboratory standard. It is intended to bring consistency of measurement across different manufacturers and films. Assuming the manufacturer has done their job properly is IS the laboratory standard speed of the film. That means that everyone gets an ISO of 100 with Acros II. But this is only obliquely related to what any given individual will actually realize in practical use.

That is an incredible mischaracterization of the ISO standard. What made Jones' testing unique is that for the first time instead of basing a method on what was assumed important from a sensitometric perspective, Jones began with the end result of the photographic process and worked backward. From L.A. Jones and C.N Nelson's A Study of Various Sensitometric Criteria of Negative Film Speeds, "These series of prints were judged by 200 observers, each observer being requested to choose the first excellent print in each series. In this way, a statistical psychophysical evaluation of the effective camera speeds was obtained. It was recognized, of course, that such a method is much too complicated and laborious to permit of its application in practice and that for such a purpose, it is desirable or, in fact, imperative to find a sensitometric method to which will yield results in close agreement with those obtained by the direct psychophysical method." The results from various sensitometric methods were compared to the judged prints or to the print speeds and their correlation graphed. This is from the testing done in the 50s which lead to the 1960 standard and the use of the Delta-X Criterion, which is a short hand version of the fractional gradient method, as the speed method.

The "laboratory" aspect is to control the desired variables and limit the undesirable variables. Instead of laboratory, why not use scientific?

[

I have yet to see any film hit full ISO speed in practice when using conventional development

That is quite a declarative statement. Where is the proof? What method did you use to compare to the ISO speeds and what is the level of confidence of its accuracy?

You refer to the Zone System a number of times so I am going to use its testing method as an example. Zone System speed point is four stops down from the metered exposure. The EI is determined when the exposure falls at 0.10 about Fb+f.

The metered exposure for a given speed setting, creates an exposure of 8/EI at the film plane. The black and white speed point of 0.8/EI or 0.8/Hm falls 10X to the left, or Δ1.0 log-H. Four stops is equal to Δ1.20 log-H. That means, testing the same film will result in film speeds 2/3 of a stop different between the two methodologies.

Many Zone System users recommend rating the film at ½ the ISO speed. The third of a stop discrepancy from the 2/3 stop can easily be attributed to inaccuracies in testing or simply rounding. When adjusting for the difference in methodologies, any Zone System test resulting in speeds ½ to 1 stop below the ISO speed actually indicates the film is achieving ISO speeds.

That’s why it’s important to state the testing method or more precisely the interpretation method. With ISO speeds, simply using ISO before the speed indicates the standards were followed.

 

[Scott J.]

It also would help to know what developer Foma chose and what developing regime they followed in conducting their ISO testing.

That's a great point. The section of the ISO standard that pertains to development (Section 5.4.2) doesn't specify a developer, dilution, method, or temperature. It simply says manufacturers who use the ISO standard should disclose this information to users.

I looked at the Foma 400 data sheet (https://www.foma.cz/en/fomapan-400) and it doesn't say what developer, time, or temperature they used. Now, in all fariness to Foma, it's rare to see that kind of full disclosure reported in a data sheet, so they're not unusual in that regard. What I did find interesting, however, is that their film speed vs. development time curves for various developers all show maximum ISOs of between 250-320. None of the curves actually touch the 400 ISO line for the range of development times given.

 

[Steven Lee]

I looked at the Foma 400 data sheet (https://www.foma.cz/en/fomapan-400) and it doesn't say what developer, time, or temperature they used.

It does. Page two: they show curves for D76, Microphen, Fomadon, Xtol, and LQN with temperature and times. They even describe their agitation method. Microphen and LQN get to about ISO 320, others are around 250. So that's clearly not an ISO 400 film.

 

[Scott J.]

It does. Page two: they show curves for D76, Microphen, Fomadon, Xtol, and LQN with temperature and times. They even describe their agitation method. Microphen and LQN get to about ISO 320, others are around 250. So that's clearly not an ISO 400 film.

They show development curves for various developers, yes. But they don't identify which one (if any) was the basis of their ISO speed determination. And again, none of the curves shown actually touch 400 ISO. the ISO standard allows for fractional speed definitions (e.g., ISO 320, ISO 250, etc.), so it's not clear where Foma's ISO 400 rating is coming from. Maybe they just rounded up out of optimism?

 

[Steven Lee]

Maybe they just rounded up out of optimism?

That's what I always thought.

 

[chuckroast]

Hope you don't mind, but I played a little with your image and it appears shadow detail isn't all that bad. The image just appears to have been printed heavy. The negative should have even more and would be a better way to evaluate the exposure.

View attachment 347134


That is an incredible mischaracterization of the ISO standard. What made Jones' testing unique is that for the first time instead of basing a method on what was assumed important from a sensitometric perspective, Jones began with the end result of the photographic process and worked backward. From L.A. Jones and C.N Nelson's A Study of Various Sensitometric Criteria of Negative Film Speeds, "These series of prints were judged by 200 observers, each observer being requested to choose the first excellent print in each series. In this way, a statistical psychophysical evaluation of the effective camera speeds was obtained. It was recognized, of course, that such a method is much too complicated and laborious to permit of its application in practice and that for such a purpose, it is desirable or, in fact, imperative to find a sensitometric method to which will yield results in close agreement with those obtained by the direct psychophysical method." The results from various sensitometric methods were compared to the judged prints or to the print speeds and their correlation graphed. This is from the testing done in the 50s which lead to the 1960 standard and the use of the Delta-X Criterion, which is a short hand version of the fractional gradient method, as the speed method.

The "laboratory" aspect is to control the desired variables and limit the undesirable variables. Instead of laboratory, why not use scientific?

View attachment 347135 [



That is quite a declarative statement. Where is the proof? What method did you use to compare to the ISO speeds and what is the level of confidence of its accuracy?

You refer to the Zone System a number of times so I am going to use its testing method as an example. Zone System speed point is four stops down from the metered exposure. The EI is determined when the exposure falls at 0.10 about Fb+f.

The metered exposure for a given speed setting, creates an exposure of 8/EI at the film plane. The black and white speed point of 0.8/EI or 0.8/Hm falls 10X to the left, or Δ1.0 log-H. Four stops is equal to Δ1.20 log-H. That means, testing the same film will result in film speeds 2/3 of a stop different between the two methodologies.

Many Zone System users recommend rating the film at ½ the ISO speed. The third of a stop discrepancy from the 2/3 stop can easily be attributed to inaccuracies in testing or simply rounding. When adjusting for the difference in methodologies, any Zone System test resulting in speeds ½ to 1 stop below the ISO speed actually indicates the film is achieving ISO speeds.

That’s why it’s important to state the testing method or more precisely the interpretation method. With ISO speeds, simply using ISO before the speed indicates the standards were followed.

It's much simpler than that. Every single film/developer combination I have tried, when shot at box ISO and developed according to the recommended time/agitation discipline has lacked shadow detail. Switching to the ZS definition for effective ASA delivered results as you note - the personal ASA showed a full stop (ish) slower.

Now you can argue that the original ISO methodology of getting 200 viewers to tell them what looked best is a better test (as controlled with scientific rigor). You can argue that my subjective idea of what constitutes "good shadow detail" doesn't constitute proof. You can argue that my meters or thermometers are all out to lunch and that's why I'm not seeing sufficient shadow density when working at the prescribed ISO and development scheme.
The problem is that my experience is echoed by a great many other experienced photographers who have found the exact same things; The ISO rating gives weak shadow detail and its typically a full stop too fast in practice.

As I noted upthread, I did several years industrial research that involved measuring human response to sensory input. The individual-to-individual variability made finding statistical significance in the results ... challenging. So I am not wildly confident that asking 200 people what makes a "good" picture is any better a measure than my own need for shadow detail.

The ISO standard is useful. It provides a consistent and controlled way to speak to film sensitivity. But practice beats theory, and there is a significant body of practice that finds far better results by using the ZS definition of speed and development discipline.

I am not terribly dogmatic about any of this. If people are getting satisfactory results with ISO marked speed, Godspeed to them. We each work in our own way to our own vision.

N.B. All of this is pretty much beside the point anyway. The biggest sin I see committed in monochrome photography is a lack of local contrast even if the entire SBR is captured. This yields flat, boring images irrespective of the shadow detail ...