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Same film, same developer, very different results?

Evan_Mathis

Member
Joined
Jan 8, 2026
Messages
26
Location
Los Angeles, CA
Format
Medium Format
I just prepped a brand new batch of PyrocatHD and made a coupld of step tests to work with an app that I've been jamming on, and something weird is happening.
Both films here are Fuji Neopan Acros II, the one on the bottom is 35mm the one on the top is 120.
Both processed at the same time, 18 min @ 20°C in PyrocatHD (this has been my working time for Acros II so far with no issues)
Obviously very different results. The only difference is that i bought the 120 film a few months ago from B&H, the 35mm last week from Samy's in LA. All kept in the fridge.
The EI for the 35mm is 91 and an EI of 27 for the 120. It also looks like the burn in data on the edge of the film is much lighter on the 120.
Do you think this is a case of me being sold expired 120? There is the possibility that the 50mm Mamiya Sekor C lens might have a mal-adjusted shutter, but that wouldn't account for the burn in being so light and the different shades of the film base...
Thoughts?

 
Fuji lists both 120 and 135, 7 1/4 minutes in D-76 @ 20°C. So theoretically both films should behave the same. I would be surprised if either store is sitting on old film. I am a XTOL or HC-110 type. I would look at your chemistry first. MHOFWIW

Oh yeah, Welcome! Look for some others here to offer another explanation.
 
Evan_Mathis said:
that wouldn't account for the burn in being so light and the different shades of the film base...
Click to expand...

120 and 135 are coated on a different base, so that they're of a different color isn't surprising. The blue color of the 135 is part of the anti-halation package of this film; on 120 this is handled differently, I assume on this film also with a dye that's included in either the backside anti-curl coat (which 135 lacks altogether) or underneath the image layer.

Edge print is generally not of controlled density so you can't say much on that basis.

For the difference in densitometry I'd primarily look for methodological problems on your side.
 
I have recently shot expired, non-frozen Acros from multiple batches, 35mm and 120, expired 10-20 years ago. None of it had speed that dropped very much at all, exposing it at 50 always resulted in what looked like slight overexposure. I know it's not precisely the same film, but I'd be surprised if your fresh Acros II had dropped to such a low speed.
 
The edge printing on both looks the same, not that that really matters. The content of the photos on each, however, look different. See how you metered. If there was any significant extension of the lens in the 120 photos, that could cause a bit of underexposure. What is your app testing? A spot or the overall image? The overall image in the 120 appears to be of something dark, which should end up thin on your negative. The majority of the 135 film is of the lighter background, which ends up more dense on the negative. The average density of those 120 photos would be much lower than that of the 135, because of what's in the photos.
 
Evan_Mathis said:
The EI for the 35mm is 91 and an EI of 27 for the 120.

View attachment 416235View attachment 416236
Click to expand...

Doesn't the two vastly different EI exposures make quite a difference to the look of the negs if everything else such as dev time etc remains the same ?

As no-one else has picked up on this maybe I am wrong in saying it has any effect but if it doesn't then I wonder why?

pentaxuser
 

I think he's talking about the EI based on his interpretation of the results, not the speed the film was shot at. It would be pretty hard to purposely shoot film at an odd EI like 91 or 27 anyway.
 
There's no indicating what the differences might be....same film, same developer, different everything else. you may want to set up a controlled experiment if your curious.
 
To be clear, these were both exposed at box 100, used the same grey card and the same spot meter in the lighting conditions in the same setup 5 minutes apart. I was doing everything that i could to make sure the tests were as close as possible. The EI was determined by reading the grey card exposures and putting them into Zone Lab

I was using known good lenses on both, one in a Mamiya RB67 ProSD with a tested 50mm Sekor C, the other in a Leica M5 with a 40mm Voightlander Nokton.

Fair point on the anti-halation layer on the 35mm. I didn't really consider that.

I had a roll of ancient Fuji Neopan SS 120 that I processed a couple weeks ago that seemed fine.
 
retina_restoration said:
Two different cameras, two different lenses, two versions of Acros. And you’re surprised that the negatives don’t look exactly alike? I mean, come on.
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The films should technically be the same, Neopan Acros II. The camera and lenses are tested accurate. The lighting and metering and grey card are the same. The development processes are exactly the same (and according to the manufacturer they should be)

And of course there will always be some variance, that's absolutely expected.

But not 3 or more full stops difference using the same processes, no?
 
When I taught Photo 101 at a local community college in the 80s and 90s one of the class exercises was have class take their 35mm cameras with a 50mm lens. Cameras in those days ranged from all mechanical workhouses like Nikormate and Minolta 101 to newer electronic Canon A1 and Pentax MEs. Metering the same scene a class of 15 to 20 at the extract time of day we had up to thee stop range in exposures. My old mechanical Nikons, Minoltas, Konicas and Mirands vairy by 1 stop to a stop and a half, while my Minolta A mounts and Nikon F4 are with a 1/2 stop. Shutters, meters age and will differ.
 
koraks said:
That's also not plausible with film that is at most a few years out of date, and possibly not even expired to begin with. So the plausible reason is still that something's amiss in the methodological setup of your experiment.
Click to expand...

I don't disagree.
I shoot expired film all the time. It's never as bad as expected.
That said, I have had grey market films go wonky tho. I've also had manufacturer defects - shitty batches of emulsion.
That's why this whole thing is perplexing to me. These cameras are not new to me, (well the Leica is). But I've been shooting the Mamiya for almost 30 years and had it and the lenses intermittently CLA'd and tested as necessary.

I'm 100% happy to find and admit to any mistake in my process if there is one.
 
Evan_Mathis said:
The films should technically be the same, Neopan Acros II. The camera and lenses are tested accurate. The lighting and metering and grey card are the same.
Click to expand...
Well, that's not the point. Once you are comparing two different cameras/lenses, you've introduced some potentially significant differences — the contrast of the lenses are going to be different, and there will likely be differences in the actual f-stop values, and there are differences in lens coatings, how much they flare, etc. And yes — Acros Neopan is more or less the same emulsion, but on two different substrates. Who knows what tweaks are applied to the emulsion for the different substrate? No matter what, you're looking at your tests as if comparing the same two apples, when in fact you're comparing a Spitzenburg to a Cox's Orange Pippin.

Also — and it has been said many, many times — you cannot view the density of the rebate lettering as diagnostic of anything. The density of the letters/numbers is going to vary from film to film, from batch to batch. It is not a constant.
 
The test is actually more of a comparison between the equipment than it is the film. Except there is a further variable thrown in - the flare performance and other characteristic differences between 135 and 120 films.
That being said, if the purpose of the testing is to try to adjust your procedures in order to get nearly matching results between the two specific lens and camera and film combinations, your test has been useful in that it reveals some major differences between the two setups - assuming of course that your testing method hasn't introduced another variable due to the change in film size.
 
Evan_Mathis said:
I'm 100% happy to find and admit to any mistake in my process if there is one.
Click to expand...

There must be - which is not to say I can pinpoint it. It's not just the overall higher density; it's also the wonkiness due to highly inconsistent measured densities across the tonal scale. Something's up for sure and there's no reasonable explanation that traces to the film, aging, fogging due to storage, x-rays etc.

Then there's the far higher gamma with the density at the upper end being massively for the 35mm film compared to the 120. That I can imagine could relate to a mixing error of either the batches of Pyrocat that you used. The non-linearity is not explained by this, of course.
 

The films were processed in the same tank at the same time with the same brand new batch of well mixed 1:1:100 PyrocatHD. I use an AGO film processor in the Patterson tanks that does constant agitation for the whole development cycle.
 
For clarity, I processed 5 rolls in the same developer batch. Expired 35mm Neopan SS (green), New 35mm Neopan Acros II (blue), "New" 120 Neopan Acros II (yellow), 120 Ilford Delta 100, and some ancient Rollei Retro 100 (orange). The Rollei seemed like it was a touch fast, but that was expected as I exposed it at 50 ISO (I need to re-calculate the EI because it was calculated at 100 which explains the too high EI on the chart). The 35mm Neopans seem to be in line with expectations, as does the 120 Delta 100. The only odd one is the 120 "New" Neopan.
 
And I am going to re-run this test both with Delta 100 and Acros in both 35mm and 120 at some point this weekend.
I appreciate the feedback, even the less constructive stuff. Just curious if anyone had run acros(s) a situation like this with the same films in different formats before.
 
I do with 35mm, 6X6, 6X9 and 4X5, different cameras, usually the same handheld meters, 35mm, of fashion average and newer matrix, my Mamiya Universal lens leaf shutters, the 100 is -1 stop, the 65 and 150 are stop on. Kowas are dead on one to another. 4X5, I have 127 to 210, all different. When shooting 4X5 I shoot zone, I don't have a densitomer so I shot a ring around, I have different E.I for each lens. When it was easy to have my old shutters services I would keep them matched, now I just adjust the E.I.
 
Yeah the 50mm Sekor C I used with the 120 on this run is dead on with the shutter and fstop as of a year ago.
The Leica had a DAG overhaul and was tested 2 months ago.
The meter is is a 2 year old Sekonic 858 (rip old Digilite 328, you served me well)
 
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