Speed difference between Acros II, TMX, and Delta 100 at same CI?

[Stephen Benskin]

Process promptly?

I have several studies that show significant speed differences between fresh exposure and film that has sat for several months between exposure and processing.

The test is straightforward. I put a sensitometric exposure on every other roll of film I roll as I load the cassette.

Then before processing I pull a strip of film from the loader and put a fresh sensitometric exposure on it.

Process in the same tank for the same time, I get two completely different contrast indexes and speeds.

The obvious lesson is: Process promptly.

Then you get the most speed and contrast.

The corollary is: give greater exposure and process to higher contrast index if you feel like you might delay processing.

It's part of latent image keeping. ISO 6 has it in 5.4.1 Conditioning of specimens. "The processing shall be completed in not less than 5 days and not more than 10 days after exposure for general purpose films, and not less than 4 hours and not more than 7 days after exposure for professional films." The old standard had a hold time longer than 2 hours as the effect tends to plateau after a few hours. The standard also stipulates the samples be kept at 23oC +- 2oC at a relative humidity of (50 +- 5)%.

 

[Keith Tapscott.]

Makes sense, Perceptol typically loses a stop in speed, give or take.

He may have gone over to digital imaging now.
I think he used a mamiya rb 67 and a Sinar F 4x5.
The latter he used FP4 Plus at a low ISO rating of around E.I.32-40, again he used diluted Perceptol.

 

[DREW WILEY]

Pan F was designed to accommodate about the same luminance range as color slide film. Yeah, you can tweak the contrast a little during development, but it does best when you seek out subject matter of limited brightness range, or else artificially illuminate it in that manner.

The best developer for Pan F I've used is a special tweak of PMK pyro, rating the film at 25. It's not a particularly versatile film, so I seldom shoot it. But I do have a good number of superb prints made from Pan F 120. It has its own special look.

Acros is quite different, even in spectral sensitivity. Too bad it's no longer available in sheets.

 

[Milpool]

Pan F was designed to accommodate about the same luminance range as color slide film. Yeah, you can tweak the contrast a little during development, but it does best when you seek out subject matter of limited brightness range, or else artificially illuminate it in that manner.

The best developer for Pan F I've used is a special tweak of PMK pyro, rating the film at 25. It's not a particularly versatile film, so I seldom shoot it. But I do have a good number of superb prints made from Pan F 120. It has its own special look.

Acros is quite different, even in spectral sensitivity. Too bad it's no longer available in sheets.

What's your PMK tweak?

I agree Acros sheet film would be a nice option - although I imagine at this point it would be even more expensive than Kodak so perhaps not. For some reason when original Acros was around I never got around to trying it in 4x5. Too bad I missed out. I wonder if the Quickloads worked well.

 

[Stephen Benskin]

Curve shape is also dependent on development. For example, Pan F in Seasoned Xtol, Refrema Dip & Dunk.

Comparing Fan F and Plus-X, CI 0.60. Seasoned Xtol, Refrema. Pan F was shifted to match up the curves at 0.10.

 

[Sal Santamaura]

Reports of Pan F Plus' curve's S-shape and limited luminance range are, in my experience, exaggerated. The below trial (horizontal is Zone, vertical is gross density) was exposed at EI 25, resulted in fb-f of 0.25, EI 25, CI=.50 and Dmax on the fully exposed leader of 1.77. It's got a very shallow toe and shoulder. Extrapolating using the Dmax, it probably wouldn't have run out of steam (while retaining some separation) until near Zone 14, although I only exposed through Zone 10. It's got a very straight line from Zones 3 through 8. I am very pleased with this combination's sharpness and, given how warm our ambient and tap water get here during summer, usability at elevated development temperatures. My results using 120 Pan F Plus in a Mamiya 7 are the same as this trial in a Nikon F6 with confirmed accurate shutter speeds. Both times my Pentax digital spotmeter, recently calibrated by Richard Ritter, agreed perfectly with the in-camera exposure readings.

 

[Kodachromeguy]

Pan F has an exaggerated S-curve with limited contrast range; but under the right conditions that can provide some lovely results. And with the right developer it can exhibit a special "wire sharpness" edge effect which is somewhat unique. Very different indeed from Acros.

I only used Pan-F Plus in 120 size once. It was a hazy, gloomy day with drizzle. And the results looked great. I exposed at EI = 32 and sent it off immediately for development.

https://worldofdecay.blogspot.com/2021/03/another-film-treasure-ilford-pan-f-plus.html

There are 10 rolls of Acros (original) in the freezer to start using.

 

[Lachlan Young]

Comparing Fan F and Plus-X, CI 0.60. Seasoned Xtol, Refrema. Pan F was shifted to match up the curves at 0.10.

Same here essentially. It is quite perplexing to see the amount written online (and in quite a few books, Barry Thornton being one particular offender) about how difficult Pan-F is to work with. In many cases I suspect it is the claimants effectively demonstrating the extent of their exposure & process control errors.

 

[Augustus Caesar]

Process promptly?

I have several studies that show significant speed differences between fresh exposure and film that has sat for several months between exposure and processing.

The test is straightforward. I put a sensitometric exposure on every other roll of film I roll as I load the cassette.

Then before processing I pull a strip of film from the loader and put a fresh sensitometric exposure on it.

Process in the same tank for the same time, I get two completely different contrast indexes and speeds.

The obvious lesson is: Process promptly.

Then you get the most speed and contrast.

The corollary is: give greater exposure and process to higher contrast index if you feel like you might delay processing.

I processed all these tests the same day or the next.

 

[Augustus Caesar]

Same here essentially. It is quite perplexing to see the amount written online (and in quite a few books, Barry Thornton being one particular offender) about how difficult Pan-F is to work with. In many cases I suspect it is the claimants effectively demonstrating the extent of their exposure & process control errors.

It is a difficult film to work with (as was Adox KB-14) because being very fine-grained it develops very quickly. You must use very dilute developer. You also have to expose it more than its ISO would indicate. About 25 for Pan-F and 50 for Acros. When processing films of different speeds, instead of varying time with a fixed concentration of developer, it is better to vary the dilution. For Pan-F with FX-39, I dilute about 1+22. For Delta 3200, I dilute about 1+8

 

[Bill Burk]

It's part of latent image keeping. ISO 6 has it in 5.4.1 Conditioning of specimens. "The processing shall be completed in not less than 5 days and not more than 10 days after exposure for general purpose films, and not less than 4 hours and not more than 7 days after exposure for professional films." The old standard had a hold time longer than 2 hours as the effect tends to plateau after a few hours. The standard also stipulates the samples be kept at 23oC +- 2oC at a relative humidity of (50 +- 5)%.

Right. And I know you’ve done some latent image retention studies.

I always heard some films have poor latent image keeping properties but thought my favorites held up well.

Well I was wrong. I’m seeing quite a spread in speed and contrast for old exposures vs fresh.

These shots are Panatomic-X developed promptly. I was happy how they came out. It felt like the film was fast.

Sunday I did the run that came out thin, despite longer development time. There, the exposures were aged, and the pictures are not as contrasty though the scenery was similar. It felt like the film was slow, underexposed.

I see similar spread in the contrast curves aged vs fresh in 5222.

So now in all the calculations for film speed I will be thinking about processing promptly… or giving additional 1/3 stop exposure

 

[DREW WILEY]

Milpool - Fuji's Quickload sleeves were more reliable than Kodak's Readyload ones. Neither brand had a particularly good adapter. I made my own by rebuilding an old Polaroid 545 holder; and it held the film a lot flatter (at least in my highly modified example). I used it for both Fuji and Kodak single-sided sleeves. 545 holders (unmodified) were used for the previous Polaroid sleeve system which contained early Fujichrome 50 4X5 film - certainly not very flat in that case either. But it sure beat a film tent and reloading holders out in the elements.

Toward the end, Acros sleeves were getting unreliable, and it just wasn't worth the expenditure to them (the Polaroid ghost ship corporation which Fuji contracted) to rebuild the sleeving machinery.

I still had my lightweight Mido 4x5 film holders for backpacking use, but switched mainly to Hosesman 6x9 roll film backs instead, for those longer treks in the mountains.

For awhile I shot Acros even in 8x10 - talk about some amazing detail ! - but the damn film was so slick that I had to change even my variety of anti-Newton glass in one of my enlargers to prevent rings.

 

[Lachlan Young]

It is a difficult film to work with (as was Adox KB-14) because being very fine-grained it develops very quickly. You must use very dilute developer. You also have to expose it more than its ISO would indicate. About 25 for Pan-F and 50 for Acros. When processing films of different speeds, instead of varying time with a fixed concentration of developer, it is better to vary the dilution. For Pan-F with FX-39, I dilute about 1+22. For Delta 3200, I dilute about 1+8

KB-14 was 'thin' by the standards of the early 1950s. Its emulsion layer was significantly (maybe 50%) thicker than HP5, never mind HP5+, Pan-F, or the Delta emulsions etc. Its structure was not well optimised by the standards of emulsions being released by the end of the 1950s onwards. In comparison, Pan-F was designed to behave well in ID-11/ Microphen/ Perceptol with good process control, but (from the sounds of Ilford hints) not significantly optimised/ updated for a wider selection of developers (e.g. non-aqueous ones). If you are not hitting aim speed, you are probably either developing to a too low average gradient (e.g. if you print on harder papers on a condenser enlarger) compared to ISO test conditions, your metering is wayward, or your choice of developer is causing a speed loss. None of those are really a problem if you are getting visual results you like, but they don't give any universally applicable information about the product.

 

[Milpool]

I forgot about Mido. I remember always being curious about those but never bought them.

Never tried the Kodak Readyloads either. I seem to remember John Sexton used a ton of those so I had always assumed they must work - on the other hand it might be one of those things where John had a special holder or got special versions from Kodak. If they worked well it would be worth the $ to me just to avoid having to load film, deal with all the care required to avoid dust and/or make backup exposures. But those ships have long since sailed.

The T-Max films also have the shiny emulsion side so I can't really win on that front unless I use Tri-X 320 but of course that's a different film altogether. I assume Acros II is still shiny like the old version but I'm sort of curious to try a few rolls.

Milpool - Fuji's Quickload sleeves were more reliable than Kodak's Readyload ones. Neither brand had a particularly good adapter. I made my own by rebuilding an old Polaroid 545 holder; and it held the film a lot flatter (at least in my highly modified example). I used it for both Fuji and Kodak single-sided sleeves. 545 holders (unmodified) were used for the previous Polaroid sleeve system which contained early Fujichrome 50 4X5 film - certainly not very flat in that case either. But it sure beat a film tent and reloading holders out in the elements.

Toward the end, Acros sleeves were getting unreliable, and it just wasn't worth the expenditure to them (the Polaroid ghost ship corporation which Fuji contracted) to rebuild the sleeving machinery.

I still had my lightweight Mido 4x5 film holders for backpacking use, but switched mainly to Hosesman 6x9 roll film backs instead, for those longer treks in the mountains.

For awhile I shot Acros even in 8x10 - talk about some amazing detail ! - but the damn film was so slick that I had to change even my variety of anti-Newton glass in one of my enlargers to prevent rings.

 

[DREW WILEY]

When one is being sponsored by a particular company, or being paid to promote their products, it's uncommon to say anything negative about that product. The first Readyload holders contained two sheets of film, back to back, which had a much greater risk of light leaks than the second single sheet version which came out in response to Fuji's single-sheet Quickload sleeves. The adapters or holders themselves were altered two or three times. Sad to see the convenience of those system go extinct.

Regardless, I use anti-Newton glass on both sides in all of my negative carriers. Have to in this foggy climate. Open skies in the negs are obviously the most prone to revealing Newton rings when present. And if you have to significantly boost contrast during the printing phase itself (versus during development), that only exaggerates the risk of rings becoming obvious. With roll film, its common to have a frame or two out of synch with the other exposures when it come to scene brightness range; so we accommodate via VC paper contrast controls instead.

 

[Sal Santamaura]

...resulted in...EI 25, CI=.50...

...If you are not hitting aim speed, you are probably either developing to a too low average gradient...compared to ISO test conditions...None of those are really a problem if you are getting visual results you like...

Yup. With roll film, I aim for N-1/2, enabling pleasing prints despite varying subjects of different luminance ranges on the same roll. ISO test conditions are irrelevant to me. Real world conditions are what counts.

 

[Sal Santamaura]

...Never tried the Kodak Readyloads either. I seem to remember John Sexton used a ton of those so I had always assumed they must work - on the other hand it might be one of those things where John had a special holder or got special versions from Kodak...

It seems very unlikely that Kodak made any special holder for John. Too much effort; any improvement(s) could be expected to have been incorporated into production units. What it did do, however, was provide him with Readyload packets containing emulsions that were not offered commercially in them. A simple matter of loading different film into the packet assembly equipment.

 

[Augustus Caesar]

KB-14 was 'thin' by the standards of the early 1950s. Its emulsion layer was significantly (maybe 50%) thicker than HP5, never mind HP5+, Pan-F, or the Delta emulsions etc. Its structure was not well optimised by the standards of emulsions being released by the end of the 1950s onwards. In comparison, Pan-F was designed to behave well in ID-11/ Microphen/ Perceptol with good process control, but (from the sounds of Ilford hints) not significantly optimised/ updated for a wider selection of developers (e.g. non-aqueous ones). If you are not hitting aim speed, you are probably either developing to a too low average gradient (e.g. if you print on harder papers on a condenser enlarger) compared to ISO test conditions, your metering is wayward, or your choice of developer is causing a speed loss. None of those are really a problem if you are getting visual results you like, but they don't give any universally applicable information about the product.

I use condenser enlarger, yes. KB-14 was made well into the 80s. It was very contrasty. I had the best results with Neofin Blue. Now I use only TMY-2 and FX-21 (Acuspecial).

 

[Stephen Benskin]

For any film‑speed value to communicate anything meaningful, it must be stated within agreed‑upon and reasoned conditions such as those defined by the ISO standard. Even when different conditions or criteria are chosen, that decision is never made in a vacuum. It still derives its relevance from the framework it departs from. To claim the ISO standards aren’t related to real‑world conditions is a misstatement. The ISO speed system is built on empirical research— Loyd Jones’ seminal psychophysical print studies linked exposure, development, and print quality under real world conditions to the film characteristics. The standard codifies those real‑world findings. It’s also relevant to remember there’s a distinction between film speed and EI. I'd go as far as to say the ISO speed is actually an EI. It's the Delta-X speed within the standard that is the real film speed.

 

[miha]

@Stephen Benskin so how do these three films perform for you in terms of speed?

 

[Stephen Benskin]

@Stephen Benskin so how do these three films perform for you in terms of speed?

See posts #22 & #32.

 

[miha]

See posts #22 & #32.

Thanks. I must have missed them earlier.

 

[Augustus Caesar]

For any film‑speed value to communicate anything meaningful, it must be stated within agreed‑upon and reasoned conditions such as those defined by the ISO standard. Even when different conditions or criteria are chosen, that decision is never made in a vacuum. It still derives its relevance from the framework it departs from. To claim the ISO standards aren’t related to real‑world conditions is a misstatement. The ISO speed system is built on empirical research— Loyd Jones’ seminal psychophysical print studies linked exposure, development, and print quality under real world conditions to the film characteristics. The standard codifies those real‑world findings. It’s also relevant to remember there’s a distinction between film speed and EI. I'd go as far as to say the ISO speed is actually an EI. It's the Delta-X speed within the standard that is the real film speed.

But! Those standards have problems. The much faster B&W films introduced in the mid-1950s forced photographers to use very small apertures on their lenses (f/11 or smaller) because the leaf shutters on those cameras seldom ran faster than 1/300 sec. Most 35mm cameras used leaf shutters until about 1960, ironically when the ASA standard was changed, effectively doubling the speed number. If your camera had a top speed of 1/300 sec, and a minimum aperture of f/16, and the light conditions were sunny, clanging the speed number didn't really matter. You could not avoid overexposure! So, the film speed number change was pointless for many photographers. Remember, many photographers used Kodachrome, whose speed was a blazing ASA10!

When the 35mm SLRs started appearing around 1959 (especially from Japan) and selling in large quantities, the revised film speeds led to underexposure. which continues to this day, because leaf shutters in combination with small apertures allow more light in that focal plane shutters. So, if you use a focal-plane shutter camera, you should increase your exposure (reduce the film speed setting) by about 2/3 stop, regardless of the developer or enlarger type. I have found this out by empirical testing and reasoning.

Interesting Tidbit about exposure compensatiion with leaf shutters at small apertures

I got an old copy of the "Kodak Professional Photoguide" (1979), from my local camera shop today. They have lots of useful info, especially for large format, and I like to have one handy. It's got a grey card, color patches, and lots of handy calculator dials for things like lens extension...

www.largeformatphotography.info

Shutter Efficiency w/ Leaf Shutters & Higher Speeds...

Hi everyone, So I'm looking for a practical way to determine the effect & degree of shutter efficiency at high speeds and small apertures. Or, rather than determine it myself, are there any steadfast guidelines that one can go by? I read the Leslie Stroebel book and she (he?) has an...

www.photrio.com

Something good to know about leaf shutters that I did not know.

Because the times are calibrated between half fully open and half fully closed at full aperture, the exposure time at small apertures is longer, because there isn't as much opening and closing time. 1 stop at 1/500th!

rangefinderforum.com

 

[Bill Burk]

Same tank, same film, two different ages of latent image.

This is why I am advocating for “process promptly” — it’s happening too much for me to ignore.

I used to think nothing of leaving film from summer to process in winter. I used to trust Panatomic-X latent image based on print results. And true, the photo negatives here which have the aged curve, will print fine. But I dodged trouble by developing for a good long time. Anyone who processes by datasheet times risks thin, disappointing negatives if they shoot at rated speed.

 

[DREW WILEY]

Pan F is the one with the worst latent image characteristics that I'm aware of. No need to panic, but I certainly wouldn't leave it laying around for six months before processing. Been there, done that, and regret it. One or two months shouldn't cause worry.

On the other hand, I've stumbled onto forgotten exposed sheets of TMax, Acros, and FP4 several years old, and have successfully developed them without fog or other complications.