Topic: longevity of fast films

[Steven.]

I recently bought a bunch of tmax 3200 for $2 a roll and was wondering how long they will last since i heard that fast films tend to fog easily. they're about 5-6 years expired. thanks!

[Francois]

It's true. The faster the film, the faster it will degrade.

Just give me the expiry dates and I'll ask my super powerful computer to estimate the degradation speed (OK, the computer is nothing to really brag about but it works...)

[SLVR]

i got a roll of this stuff and found that the base fogged dramaticlly. I shot it at 1600 but did some double exposures where exposures were acceptable. I would throw a roll through it at 400 or 800 and gauge the film speed from there. After that shoot it as much as you can.

[olympusOM]

Shoot a roll at a constant exposure but vary the ISO and the compare when you process.

[Francois]

A few years ago, I decided to use some old stock 800 ISO. I calculated the speed to be at around 400 and exposure was pretty close to what it would have been... with huge grain.

I also have some HP5 that of unknown origin that I use at about 100 to get decent results (though I tried it once at 1600 with some very aggressive development and got something decent on a dull rainy afternoon). And the base fog is really a sight to behold!

As a starting point, add 1 stop for every 10 years of expiry.

[Steven.]

it expired 5/2006 i think (the film is not with me so im not 100% sure) and was kept cold. i currently have it in the freezer in a zip loc baggy. im not expecting perfect results especially for the price but i was just wondering if i should use it all before a certain time. ive seen 10 year expired 3200 shot at 800 and dev'd as normal with only minimal fogging. ive also heard of people saying 1-2 years expired yields "unacceptable" results...

[Francois]

OK, I just did a bit of research.
T-Max P3200 is a film that was designed to be pushed to various speeds.
In itself, the film is an 800 ISO emulsion when processed in regular developers. It goes up to 1000 ISO when processed in T-Max developer.

Now, if I take it as a 3200 speed film, its sensitivity would now be 2000 ISO.

The film speed for regular developers would be 500 ISO. For T-Max developer, 640 ISO.

[Steven.]

"Now, if I take it as a 3200 speed film, its sensitivity would now be 2000 ISO."

so if i expose it at 1600 and develop as normal, it should turn out ok?

"The film speed for regular developers would be 500 ISO. For T-Max developer, 640 ISO."

i dont get this bit of info here..

[Francois]

Well, normally the film is 800 ISO natural speed. So, if you're using a classic developer, you expose at 500 ISO but develop using the 800 times.
If you're using T-Max developer, you expose it at 640 ISO but develop it like if it was a 1000 ISO film in T-Max dev.

As for the 1600... sensitivity and development changes proportionally. You then would need to expose it at 1000 ISO but develop like it was 1600 ISO...

The values change because my program calculates the expiry by the day and then rounds it off to the nearest ISO available on DX coding.

I hope I'm clear this time. I know it's really not obvious stuff.

[Steven.]

you're being helpful thanks i appreciate it!

i guess i was going to shoot it at 1600 to just compensate for the expiration and then just develop normally (@ 3200 for 10.5 mins according to Mass Dev Chart). would that be wrong? if so, then i'll just try shooting it at 500 and developing for the 800 times listed.

[Francois]

You could just shoot at 2000 and develop for 3200. That's about only 2/3 stop less than the regular sensitivity.

If you choose to expose the film at EI 1600 and develop it as a 3200 film, you should simply to get a slight contrast increase and a bit more density. It won't be the end of the world.

[Steven.]

ok i see thanks! i think i'll just go for the latter since its easier for me to calculate in my head.