Acros II - What speed are you getting?

Steven Lee · Aug 16, 2023

I just made a mistake of shooting and developing a roll of Acros II while on a great location. The mistake was using the unfamiliar film without testing it first. I developed it in Xtol 1+1 using the MDC time of 9.5 minutes. The negatives show decent contrast, but the shadows are crushed. This worked for some images, but not for others. Bummer.

My metering technique was the same as Delta 100, which is the film I normally shoot. Also I kept the yellow filter on with +1EV exposure compensation. According to my data set of one, Acros is significantly - at least a full stop - slower than Delta 100. I only had one roll, so I can't test its speed right now, but the curiosity is pushing me to ask here: What speed are you getting with Acros 100? How would you compare it to Delta 100 or FP4? How does it play with contrast filters, like the yellow here?

Here's how most of my images from that roll look like. Again, I am not concerned with the metering because Delta 100 turned out much better.

Alan9940 · Aug 16, 2023

After testing, I rate it at EI 80. And, I've never noticed any odd tonal relationships from filter use vs any other pancro film.

JParker · Aug 17, 2023

With my developers, I get 1/3 stop less speed with Acros II compared to Delta 100.

runswithsizzers · Aug 17, 2023

I metered <this roll> of Acros II at EI 64, but I am not clever enough to say if that was the correct decision. In most shots, I think I am seeing at least some shadow detail, so I am assuming my exposures are not too far off(?) I don't have access to a darkroom right now, so I can't comment on how these negatives print. Normally, I use Xtol at 1+1 but this roll was processed in Ilfosol 3 at 1+14. For metering, I mostly relied on the camera's built in meter (Pentax KX), although I occasionally checked that with an incident reading from my Sekonic L-308.

Some of that roll was shot with no filter, some with a yellow K2, and one with an orange O2. My feeling is that Acros may be slightly less effected by contrast filters than some other films(?) For example, I used no filter for this shot - the northern blue sky made a nice shade of gray without a filter...

---

... but for this one, taken at the same time, I used an orange filter...

Yes, the blue sky is darker with the orange filter, but maybe not as much as I would expect? However, I don't use the orange filter very often, so my expectations may not be worth much.

chuckroast · Aug 17, 2023

I get full box speed when developing it in highly dilute Pyrocat using semistand technique for an hour development time.

I have not yet tested it with conventional development but - based on a ton of testing over the years, both by densitometer and by inspection - I'd rate it at ASA 50 for D-76 1:1 HC-110B, PMK Pyro, and ASA 80 for conventional Pyrocat-HD. Those estimates have consistently been shown to be in the ballpark across many films and developers I use. I have never seen any film, in any developer hit full box speed with the recommended development times and normal agitation.

cirwin2010 · Aug 17, 2023

I haven't done any specific testing, but I believe I am getting full speed with the following development regime. I shoot a lot of night scenes and I've always been happy with the detail I get in the deepest shadows.

-Acros 100 @ 100
-Rodinal 1:100 for 18 minutes @20c
--Agitate for 15 seconds each minute for the first 3 minutes
--Agitate for 15 seconds every 3 minutes for the remaining time
(listed on Massive Dev Chart)

pentaxuser · Aug 17, 2023

runswithsizzers said:
I metered <this roll> of Acros II at EI 64, but I am not clever enough to say if that was the correct decision. In most shots, I think I am seeing at least some shadow detail, so I am assuming my exposures are not too far off(?) I don't have access to a darkroom right now, so I can't comment on how these negatives print. Normally, I use Xtol at 1+1 but this roll was processed in Ilfosol 3 at 1+14. For metering, I mostly relied on the camera's built in meter (Pentax KX), although I occasionally checked that with an incident reading from my Sekonic L-308.

Some of that roll was shot with no filter, some with a yellow K2, and one with an orange O2. My feeling is that Acros may be slightly less effected by contrast filters than some other films(?) For example, I used no filter for this shot - the northern blue sky made a nice shade of gray without a filter...

---

... but for this one, taken at the same time, I used an orange filter...

Yes, the blue sky is darker with the orange filter, but maybe not as much as I would expect? However, I don't use the orange filter very often, so my expectations may not be worth much.

Based on these two shots and Acros II speed of ISO 100 the orange filter does not look as if its power to darken the sky is a good bang for buck against the 1.5./ 2 stops speed loss or thereabouts of an orange filter

pentaxuser

Craig · Aug 17, 2023

Steven Lee said:
I developed it in Xtol 1+1 using the MDC time of 9.5 minutes.

That seems short to me. In a roundabout way I'll do a comparison.

The Fuji datsheet says the time in full strength D76 is 7¼ min, and that and ID11 are the only non-Fuji developers listed. Ilford gives 7½ for HP5 - lets call that close enough to the D76 time Fuji gives, and Ilford says to use 12 min for Xtol 1:1

I know that HP5 isn't Acros, but I would expect a Xtol 1:1 time to be longer than 9½ min.

MattKing · Aug 17, 2023

What are people using as their speed criteria?
Something akin to the ISO criteria, something like the Zone System criteria, or what?

Steven Lee · Aug 17, 2023

Thank you everyone who responded

MattKing said:
What are people using as their speed criteria?

People with densitometers and grey cards plot their own characteristic curves and use the ISO definition of film speed, I've seen at least 3 different people post their results here.

I employ a simplified version of this using HP5+ as a reference because I know its behavior well. I expose a scene on HP5+, develop it with my regular routine, and compare a new film+developer combination to that. My test scene includes a step wedge too where I can sample density with a densitometer. This way I can evaluate everything all at once: its speed, contrast, spectral response and grain character.

Should have done that before taking that roll on a trip :-(

MattKing · Aug 17, 2023

Steven Lee said:
People with densitometers and grey cards plot their own characteristic curves and use the ISO definition of film speed

Some with those resources do, and some - actually a fair number - use different definitions. Particularly the Zone system definition.
Which is fine, as long as everyone who shares a speed mentions which definition they are using.

DREW WILEY · Aug 17, 2023

No change from the original Acros. I typically rate it at 50 for a high contrast scene, to get better shadow gradation, or at full box speed of 100 in moderate contrast situations. But since the II version has a little longer straight line down into the shadows than the first version, I'm a little more comfortable with routinely calibrating it higher than 50 for PMK. It all depends on what else is on the same roll anyway, and how long that particular roll will be developed based on the preponderance of exposures on that specific roll. I factor several potential variables, but at this point, almost intuitively.
Usually, on any given roll there is likely to be an odd duck or two out of synch, contrast-wise, from the other exposures;
so I have to prioritize development for sake of any image I suspect will be the best pick of the litter.

Tony-S · Aug 17, 2023

Acros II @100 in Perceptol 1+2, 16 min at 75F, FTW!

chuckroast · Aug 17, 2023

MattKing said:
What are people using as their speed criteria?
Something akin to the ISO criteria, something like the Zone System criteria, or what?

The usual definition is the ASA that places Zone III at 0.1DU above FB+F on a densitometer. After doing (way too much) densiometric testing, I've found that pretty much every film achieves this a 1/2 box ASA when processed in inversion or open tanks, agitating every 30 seconds, and reducing development time 20% from the published recommendations. This has been true across APX 100, Tri-X, Plus-X, Efke PL100M using D-76, HC-110B, DK-50 as measured on a densitometer. By inspection, it's approximately correct for FP4+, and HP4+, and looks right for all the above films with PMK, Pyrocat-HD, and D-23.

In this case, 'looks right' means that there is meaningful shadow detail when using "1/2 box ASA, -20% development" rule-of-thumb. Or, at least, it's a good/close enough starting point. PMK is the outlier here because it oxidizes so fast. When using this developer, I use 1/2 box speed, agitate every 15 seconds, and develop 12-14 minutes for pretty much everything.

Obviously, this will vary with bad meter calibration, flakey thermometers, shutters out of whack and so on, which is why everyone needs to determine their own "personal ASA" that takes these variables into account.

Monochrome film is pretty forgiving of slight (<1 f/stop) overexposure, but underexposure is punished badly. So, when I have to guess with a new film, I always guess toward slightly more exposure.

ASA is a little bit like EPA mileage estimates for new cars. They're not intended to be absolute measures but a way to compare one brand to another. A 400 ASA film should reliably require 1 less stop of exposure than a 200 speed film shooting the identical scene, but the actual calibrated value has to take into account agitation style, thermometers, and so forth.

As an aside, up until the late 1950s-ish, ASA was determined to be the speed at which a film would give us a "usable" image (according the the Gods of Kodak et al). Somewhere around then, the definition changed to be "the ASA required to get a minimal image on film" and ... pretty much overnight, ASA's doubled. This isn't the exact formal definition of what changed, but it's roughly true. So, today's youngsters shooting a box speed are consistently underexposing a full stop and producing thin negs with very limited shadow detail.

DREW WILEY · Aug 18, 2023

"Usual definitions", especially when they're generically based on ZIII, don't necessarily work all that well. But this is not the place for yet another explanation for why Zonies don't always get it right. I wouldn't call Acros quite as tolerant as FP4, but I can actually develop sheets of both together for the same amount of time and get reasonably matching results. Of course, ACROS is no longer made in sheets, so once my last box of 4x5 is used up, that won't apply in my case ever again.

chuckroast · Aug 18, 2023

DREW WILEY said:
"Usual definitions", especially when they're generically based on ZIII, don't necessarily work all that well. But this is not the place for yet another explanation for why Zonies don't always get it right. I wouldn't call Acros quite as tolerant as FP4, but I can actually develop sheets of both together for the same amount of time and get reasonably matching results. Of course, ACROS is no longer made in sheets, so once my last box of 4x5 is used up, that won't apply in my case ever again.

Well, I've got years of densiometric testing under my belt that says otherwise. Sure, a slavish devotion to some magic number is foolish. But having some kind of baseline is useful. It is my consistent experience that people who say what you have above have never tested much and have never controlled for variables like shutter speed, thermometer accuracy, water variability and so forth. It is also my consistent experience that people who do not do this initial testing, or at least build their own baseline have lousy shadow detail and blow highlights out.

ZS isn't magic. It's an attempt to eliminate variables so one can concentrate on the expressive part of photography. Getting that stuff out of the way opened the door for me to work on vision and not constantly have to guess whether I had shadow detail or highlight blowouts.

Like I said, I did enough testing that 1/2 box ASA, -20% development is close enough to get most film/dev combos very close to where they should be.

Steven Lee · Aug 18, 2023

> So, today's youngsters shooting a box speed are consistently underexposing a full stop and producing thin negs with very limited shadow detail.

@chuckroast Thank you for responding, but I respectfully disagree with your overgeneralization. Ektar 100 and HP5+ deliver excellent shadow detail when exposed at box speed, assuming intelligent metering and Flexicolor/Xtol development.

craigclu · Aug 18, 2023

I settled on shooting at 80 and this was what the first version worked best at for me. I use mainly PyroCat with it.

chuckroast · Aug 18, 2023

Steven Lee said:
> So, today's youngsters shooting a box speed are consistently underexposing a full stop and producing thin negs with very limited shadow detail.

@chuckroast Thank you for responding, but I respectfully disagree with your overgeneralization. Ektar 100 and HP5+ deliver excellent shadow detail when exposed at box speed, assuming intelligent metering and Flexicolor/Xtol development.

I just shot some HP5+ under very controlled conditions and the only way I hit full box speed was to semistand develop it. I stipulate that there may well be a film/dev combo that really does hit full speed with ordinary time and agitation, but I've never seen it.

What most often happens when I hear people saying "But that doesn't apply to me" is that they have a miscalibrated meter, a slow shutter, of some other unaccounted for darkroom variable like a bad thermometer.

I cannot speak to this specific combo since I do not use Xtol or Ektar, but among the many film/dev combos I've actually tested myself, not one has hit box speed with manufacturer recommended development time and agitation.

I would also mention that there is always the possibility that my reference meter against which all my other meters are calibrated reads one full stop low and hence gives me the results above. As always, we seek repeatability and consistency, not absolute accuracy, so if your process gives you full box speed with your preferred film/dev combo, by all means go for it. It's just that I've seen so very many negatives that are unreasonably thin when people choose to shoot at rated ASA.

MattKing · Aug 18, 2023

chuckroast said:
The usual definition is the ASA that places Zone III at 0.1DU above FB+F on a densitometer

So essentially a Zone System speed, rather than the ISO speed.
Complete with the built in offset (~2/3 of a stop) between the two.
Which is fine, if you build your analysis on the method you yourself use.
But if you are sharing your results with others, it is useful to mention your choice of method.

chuckroast · Aug 18, 2023

MattKing said:
So essentially a Zone System speed, rather than the ISO speed.
Complete with the built in offset (~2/3 of a stop) between the two.
Which is fine, if you build your analysis on the method you yourself use.
But if you are sharing your results with others, it is useful to mention your choice of method.

It's more usually about 1 difference, but yes, sharing with the class is pretty useful.

The thing is that films used to be rated at half the ASA they are today when the goal was "expose enough to make a decent image". When that changed to "expose enough to get anything at all on the negative" ASAs magically doubled overnight. So "ISO Speed"
really isn't a good practical indicator of the exposure needed to get to reasonable shadow detail. It's just a relative measure of how one film stacks up against another. It's more of a nerdy densiometric definition of speed than it is a practical measure for the working photographer.

I hasten to add that I am not doctrinaire' about any of this. People's meters, shutters, and darkroom technique vary enough that everyone should figure out what works for them. I have personally checked many meters, and more importantly, many shutters and its pretty shocking how much they vary from nominal. A large format shutter - even when newly CLAed - will typically be slow 1/2-1 full stop at the highest speed. The remaining speeds will be between 1/3-1/2 a stop away from nominal - again, this is based on many, many tests I've done here.

I don't share the BTZS obsession with fractions of a stop of accuracy. I work to get consistency so I don't have to think too much about exposure - my workflow is so nailed down after many decades of doing this, it just sort of works for me. I would note that even decades of experience don't prevent me from doing dumb stuff now and then, though ...

John Wiegerink · Aug 18, 2023

chuckroast said:
It's more usually about 1 difference, but yes, sharing with the class is pretty useful.

The thing is that films used to be rated at half the ASA they are today when the goal was "expose enough to make a decent image". When that changed to "expose enough to get anything at all on the negative" ASAs magically doubled overnight. So "ISO Speed"
really isn't a good practical indicator of the exposure needed to get to reasonable shadow detail. It's just a relative measure of how one film stacks up against another. It's more of a nerdy densiometric definition of speed than it is a practical measure for the working photographer.

I hasten to add that I am not doctrinaire' about any of this. People's meters, shutters, and darkroom technique vary enough that everyone should figure out what works for them. I have personally checked many meters, and more importantly, many shutters and its pretty shocking how much they vary from nominal. A large format shutter - even when newly CLAed - will typically be slow 1/2-1 full stop at the highest speed. The remaining speeds will be between 1/3-1/2 a stop away from nominal - again, this is based on many, many tests I've done here.

I don't share the BTZS obsession with fractions of a stop of accuracy. I work to get consistency so I don't have to think too much about exposure - my workflow is so nailed down after many decades of doing this, it just sort of works for me. I would note that even decades of experience don't prevent me from doing dumb stuff now and then, though ...

Yes, almost all the mistakes I make are not camera, film or developer related problems. I'm usually the culprit. The older I get the more methane gas builds up in my brain and at the most unexpected times a brain fart is released. Very embarrassing to say the least.

pentaxuser · Aug 18, 2023

chuckroast said:
It's more usually about 1 difference, but yes, sharing with the class is pretty useful.

The thing is that films used to be rated at half the ASA they are today when the goal was "expose enough to make a decent image". When that changed to "expose enough to get anything at all on the negative" ASAs magically doubled overnight. So "ISO Speed"
really isn't a good practical indicator of the exposure needed to get to reasonable shadow detail. It's just a relative measure of how one film stacks up against another. It's more of a nerdy densiometric definition of speed than it is a practical measure for the working photographer.

I wonder why films' speed were changed Was this all the manufacturers' joint decision to "improve" speed for marketing reasons or did it come from some kind of independent body who felt that their study of film speed indicated that ASA based on the current definition of how you test for film speed was a fairer representation of what the film would then produce for the average user who represents nearly all of the market

Or was the change made for none of those reasons?

Thanks

pentaxuser

John Wiegerink · Aug 18, 2023

pentaxuser said:
I wonder why films' speed were changed Was this all the manufacturers' joint decision to "improve" speed for marketing reasons or did it come from some kind of independent body who felt that their study of film speed indicated that ASA based on the current definition of how you test for film speed was a fairer representation of what the film would then produce for the average user who represents nearly all of the market

Or was the change made for none of those reasons?

Thanks

pentaxuser

I too can't figure out why we changed to ISO from ASA, but it doesn't matter one way or the other I guess.

pentaxuser · Aug 18, 2023

John Wiegerink said:
I too can't figure out why we changed to ISO from ASA, but it doesn't matter one way or the other I guess.

Thanks John but it wasn't that change I was referring to. It was the change that chuckroast was referring to when in the early 60s, I think, the new standard on which ISO is based came into being. As far as I know ISO was simply the direct successor to ASA but was a notational change and not an apparent speed increase

pentaxuser

Acros II - What speed are you getting?

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