I came across some expired TX 400 (1991), and some HP5 (1986). Is there a general formula on how to shoot these rolls (or any other film for that matter), e.g. reduce ISO by X depending on how many decades, etc.?
I I usually overexpose by a stop or two, since you can recover from a denser negative, but if the emulsion has aged to where it's no longer sensitive enough, then underexposure will yield it pretty useless.
There's no formula I'm aware of since it's entirely dependant on the film and the condition it had been kept in.
This was Verichrome Pan 125 that expired in 1972, I shot it as 125, and developed it as you would normally. It was a foil sealed 120 roll that sat in the basement of the camera store the whole time.
Camera: Mamiya RB67
Lens: Mamiya 90mm f/3.8C
Film: Kodak Verichrome Pan 125
Where as this Tri-X 120 roll also expired in 1970s, stored in similar conditions went into 'super-grain' mode.
Camera: Mamiya RB67
Lens: Mamiya 90mm f/3.8C
Film: Kodak Tri-X (expired sometimes in the 70s)
Developer: Kodak HC-110 Dilution B @ 68F
Scanner: Nikon Super Coolscan 8000 ED
And I have several 135-36 rolls of Kodak TMax P3200 that only expired in 2004, but has aged much worse than the other stuff (apparently P3200 ages badly). Can get a decent result scanned out of it if you shoot it as ISO 400 (develope as 3200), but kind of defeats the point of P3200 especially when it has much more grain than equivalent 400 speed films. Though I'll try Microphen with the other rolls and try for 800 or 1600 to see what I can get (the base density of the negatives due to age makes it harder to get good contrast).
Canon 7 Rangefinder (1961)
Canon 50mm f/1.8 Type 6 (8 bladed aperture with curved edges on the octagon, serenar style optics)
Kodak TMax P3200 (expired in 2004, not refrigerated, kept at room temperature)
Developed in Kodak HC-110 Dilution B, 68F 10.5 minutes, Agitated once every minute (a 'tap' every 30 seconds in between)
Scanned on a Canon FS4000 dedicated 35mm film scanner.
Where as this UltraTec stuff (which I have a bulk roll of) expired sometimes in the 90s, and yet still yields a very nice image (I need to rate it around ISO 3, and looking at other developer combinations to see what I get).
But the bulk roll of Plus-X I have that expired in the late 80s seems to barely yield a latent image.