Very odd problem with Foma 400 bulk roll

Paul Howell · 2025-06-26T18:57:43-0400

A few months back I bought a bulk 100 foot roll of Foma 400. The first rolls all came out well, E.I, 320 to 250 depending on the camera and developer. I used Acufine, Diafine at 320, D76 and HC at 250. Then the roll seems to have lost 2 to 3 stops of speed. At first I thought my developers were just getting old, toss the developers, then thought my camera was off. I had been using a Minolta 800si, then I used a 600si, and today Minolta X700. I am now using Clayton F76+, a roll of Foma 200 came out spot on, the roll of bulk loaded Foma 400, 2 to 3 stops off. I shot at 250, developed for 8m at 68 degrees 1:9. After I doubled checked the X700 with my Gossen meter, spot on. The bulk load in well within date, never had such an issue. Tommarow I going to shoot a ring around with a large test chart and see what ISO it is acutally shooting at, best guess at this point is 50.

boring old man · 2025-06-26T21:09:29-0400

I could believe a faulty thermostat could cause ripening or finishing temperatures to be too low, and cause the emulsion to be lower speed (or too high and create fog), but I wouldn't expect it to change mid roll. Even if emulsions are added to the coating hopper mid coat, I would expect the film to show multiple speeds, and I don't believe there's a way to load backwards and shoot through the AH layer. Do you have a roll that looks properly, and then under exposed? Even if the film did transition between emulsions, I doubt you would cut the film at exactly the transition spot, or that it would be dead straight across the base.

mshchem · 2025-06-26T21:19:00-0400

My thought is to check camera with a roll of something else like Tri-X or HP5, factory loaded cassettes. Use a fresh factory developer too.

These new fangled E-lectronic cameras can't be trusted.

Sunny 16 some of it in manual.

Paul Howell · 2025-06-26T22:12:35-0400

mshchem said:
My thought is to check camera with a roll of something else like Tri-X or HP5, factory loaded cassettes. Use a fresh factory developer too.

These new fangled E-lectronic cameras can't be trusted.

Sunny 16 some of it in manual.

I did with a roll of Foma 200, it came out fine.

Paul Howell · 2025-06-26T22:16:32-0400

mshchem said:
My thought is to check camera with a roll of something else like Tri-X or HP5, factory loaded cassettes. Use a fresh factory developer too.

These new fangled E-lectronic cameras can't be trusted.

Sunny 16 some of it in manual.

I will use a Konica T with 50mm on manual with a Gossen SCB meter. I have fresh bottles of Clayton F76+ which is single use, both the Acufine and Dinafine were replenished and were getting a bit long in the tooth, although in the past I've had replenished Dinafine going for a year.

mshchem · 2025-06-26T23:00:10-0400

Paul Howell said:
I did with a roll of Foma 200, it came out fine.

mshchem · 2025-06-26T23:00:26-0400

Paul Howell said:
I will use a Konica T with 50mm on manual with a Gossen SCB meter. I have fresh bottles of Clayton F76+ which is single use, both the Acufine and Dinafine were replenished and were getting a bit long in the tooth, although in the past I've had replenished Dinafine going for a year.

mshchem · 2025-06-26T23:01:24-0400

I wonder if Foma spooled the wrong stuff?

koraks · 2025-06-27T01:27:53-0400

Paul Howell said:
Then the roll seems to have lost 2 to 3 stops of speed.

Not a chance. This is some form of user error; the tricky bit is figuring out what happened exactly.

Raghu Kuvempunagar · 2025-06-27T02:59:17-0400

Just a wild guess. By any chance were the speed-loosing rolls spooled such that the base faces the lens when loaded into the camera, as one would do for redscaling of colour films?

Agulliver · 2025-06-27T03:50:06-0400

I cannot begin to think of how a standard B&W film like Foma 400 could lose 2-3 stops in a short time. It's hardly the world's most advanced film but it's reliable stuff.

Are you bulk loading into DX coded cassettes? Are you using the DX coding? I am not familiar with the cameras you mention so I don't know if they detect DX coding but it strikes me that could be one error if the cassettes are not coded correctly, or of the contacts in the cameras are dirty. A number of cameras annoyingly don't actually indicate what ISO is selected when DX coding is used.

As another poster suggested, are you certain that the film was bulk loaded correctly with the emulsion facing the lens/shutter?

This must be some kind of user error or user equipment failure. A bulk roll doesn't suddenly lose 2-3 stops.

Donald Qualls · 2025-06-27T08:25:15-0400

Raghu Kuvempunagar said:
By any chance were the speed-loosing rolls spooled such that the base faces the lens when loaded into the camera, as one would do for redscaling of colour films?

This is a possibility, though I'd expect to lose more than three stops in this case. The one time I've done this (misloading film in a plate camera's film sheath) the loss was four to five stops.

Very odd problem with Foma 400 bulk roll

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