How can I test an unknown roll of film for ISO and whether it’s color or black and white?
Asked 12/6/2018
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I have some unbranded or unlabeled “mystery film” and want to identify it by testing. One roll was processed as black and white and came out very contrasty. Can I shoot frames on the same roll at different exposure/index settings to estimate the film speed, or do I need to dedicate whole rolls to one ISO each? Also, is there any way to tell whether the film is color or black and white from camera settings alone, or does that only become clear during processing?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
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1 - Can I shoot several photos on the same roll with a different ISO setting on the camera and then see which one comes out looking the best? (Or do I have to shoot entire rolls at different ISO settings?)
You can and you should shoot test shots using several different exposure settings - simply keep track of them on a notepad. Set the camera on a tripod at a decently lit object and start at ISO 12 (it's old film, it probably got slower so start low). Personally, I'd shoot manual - get the first frame to a good exposure by way of the meter and then modify shutter speeds from there. For example:
- Frame 1, metered for ISO 12: 4s, f/5.6
- Frame 2 would then be: 2s, f/5.6 (assumed ISO of 24/25)
- Frame 3: 1s, f/5.6 (assumed ISO of 50)
- Frame 4: 1/2s, f/5.6 (assumed ISO of 100)
- Frame 5: 1/4s, f/5.6 (assumed ISO of 200)
- Frame 6: 1/8s, f/5.6 (assumed ISO of 400)
- Frame 7: 1/15s, f/5.6 (assumed ISO of 800)
- Frame 8: 1/30s, f/5.6 (assumed ISO of 1600)
And so on and so on. By decreasing the shutter speed, you are effectively treating the frame as if it's ISO were twice that of the previous frame.
When you've developed the roll, see which frame has the best exposure. This frame is the ISO you would then use to shoot other rolls. (Make sure that you are choosing a developer and sticking with it for these rolls unless you have an absolute ton of rolls to add that extra variable into the mix)
2 - Is there a way to "guess" whether it's color or black and white just by trying different settings in the camera?
No, the camera isn't going to know what type of film you've loaded. If the cannister had a DX code - then maybe. Your other question made it look like there wasn't one.
Other point: If it's C-41, it'd have an obvious orange backing. I don't know what C-22 looked like but it was in use during the era and so it is possible that your film is C-22. Both would develop in B&W chemistry.
Originally by user67377. Source · Licensed CC BY-SA 4.0
user67377
7y ago
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Generated from our catalog & community — verify before relying on it.
Yes—shooting different frames on the same roll at different exposure settings is a good way to test unknown film. Keep careful notes for each frame. A simple approach is to photograph the same evenly lit subject on a tripod and bracket exposures, starting at a low effective ISO if the film is old, since old film often loses speed.
It’s better to think in terms of exposure, not the camera’s ISO dial itself: changing the ISO setting just changes the meter’s recommendation. Record each frame’s shutter/aperture so you can compare results after processing.
To determine whether it’s color or black and white, camera settings won’t tell you. That depends on the film and especially on how it is processed. If color film is processed as black and white, you’ll get black-and-white images, so in-camera testing alone won’t identify that reliably. The clearest clue usually comes from the developed negatives and the process used.
Also, if the film is old or unknown, expect higher contrast, fogging, and less predictable results.
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