Shooting mystery film found in 1930s camera

Question

Recently I purchased a German fold-able camera which was produced in about early 1930s. Got it from camera collector who told me he never tried that camera.

To my surprise when I got this camera home, I've discovered that there's still film inside of it (I can see backing paper of the film through the window that shows frame #4).

Now I absolutely want to finish the roll and develop it. The problem is I have no idea what film is inside and how old it is.

The strategies I'm thinking about:

1. Just bracket all 4 remaining exposures (the camera is 6x9, so there's 8 in total). But here's a thing: potentially the film could be about 90 years old (probably not but theoretically), using the "add one stop per decade" it makes about 9 stops. I googled that films from those years are typically 25-100 ISO range. So in the best case scenario I'll be dealing with film of about 0.12 ISO. But at the same time the film could be a couple decades old only. This will give me theoretical range of 7 stops, which I can't properly cover with only 4 exposures left.

2. Wind the film in camera. Take it out. Rewind it back to intake spool in darkroom. Take a look at backing paper and try to figure out what ISO the film is and when it was produced (not even sure if I will be able to get any info from the backing paper). Then load again, wind to frame #4 and shoot having at least some info about it. The con is: I'm pretty afraid to ruin the film during the rewind process.

Question:

What's your best strategy in this situation? How would you develop it?

Answer 1

I've got some experience with "found film" -- it's a lot of fun.

First, don't expect much; film that stood in the camera, potentially for decades, is likely to be heavily fogged and show mottling and/or wrapper offset (where the ink on the backing has fogged the emulsion in contact with it on the supply and takeup spools).

Second, you'll likely find that the film has taken a very strong curl, making it difficult to load into a developing tank for processing.

Third, if it turns out to be color film, it's very likely it's an obsolete process like C-22 or Agfa's equivalent from the 60s or 70s.

The good news is, if you get anything from the film, the first three or four frames might well be like ghosts from the past, images of people or events that are otherwise long forgotten.

I'd suggest treating the film like ISO 100 -- but then give at least two stops additional exposure to try to push your new exposures through the age fog. Process in a low-fog developer like Rodinal or, if you can find some, the old style "syrup" HC-110. Before the mid-1950s, all black and white films had a standardized process, like C-41 films have now. It was (and no, this is not a typo, it was really long): seventeen minutes at 20C/68F in D-76 stock solution. Similar or the same would apply for HC-110 Dilution B, which is what I'd recommend (though from what I've read, the new HC-110 isn't as good against fog as the syrup I used to use).

In the end, be prepared to get nothing, either from the decades-old exposures, or your new ones on the old film -- and anything you do get will be a beautiful surprise.