Pinhole + expired film

For f/180 on Delta 100, in Sunny 16 conditions, you need about 12 seconds without reciprocity correction. i don't offhand recall the reciprocity break for Delta 100, but Ilford films generally want 2.8x per stop past one second -- you're 3.5 stops past one second as "metered" so you should be okay with 2.8^3.5 = 35-40 seconds.

FWIW, I have an Android app called just "Reciprocity" that does a pretty decent job calculating reciprocity for a good selection of films. Hint: if you're going to shoot of lot of pinhole in dimmer than "Sunny" conditions, avoid Fomapan -- it's got about the worst reciprocity characteristics of any film still available. I've had multi-minute exposures on Foma 400 at f/250 or so...

babolix said:

Hi there!
I've been shooting only digital for many years and I'm very rusty on film, but I recovered a handmade pinhole camera ( made of cardboard! f should be about 180) and I found some old film rolls I haven't used yet, Ilford D100 and D400 Professional (black and white 120) expired in 1998 and stored at room temperature. I'd like to use them but I'm afraid of exposure times. The calculations are complex but could anyone give me any tips? As for the pinhole camera I just remember that ISO 100 in direct sun is ½ sec and in partial cloud is 1 min.
Thanks in advance.

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I usually pull my film a stop for each 10 years since the film was expired.
Make sure you keep a log of exposure times you used and what you took a picture of, or copy the photo with your smartphone for future reference.
You can also try different exposures for the same shot and see what comes out best.

Good luck! Show us what you got!