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In order to try and identify the correct type of "Mystery Film" that I bought and mentioned here, I would like to make a few tests.

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?)

2 - Is there a way to "guess" whether it's color or black and white just by trying different settings in the camera?

The first roll I shot was processed as black and white and came out very contrasty. I liked the results but I'm curious to try and test the film since I often buy unbranded / unlabeled films.

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    \$\begingroup\$ You likely have black and white film since you processed it as such and it came out "contrasty". Color film usually has an orange mask and would have low contrast when processed as black and white. \$\endgroup\$
    – xiota
    Dec 7, 2018 at 1:03
  • \$\begingroup\$ Recording film is usually used for photo instrumentation applications not for pictorial work (unless you like the effect.) \$\endgroup\$
    – Stan
    Dec 7, 2018 at 2:12
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    \$\begingroup\$ If you meter a grey card and process it correctly, the resulting density will be 0.3 over the base + fog density (the density reading between the sprocket holes or between frames). You'll need a densitometer to read it. That's one way to tell the ISO speed. Work backwards from the reading of that frame to calculate the effective ISO. \$\endgroup\$
    – Stan
    Dec 7, 2018 at 2:17

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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.

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    \$\begingroup\$ @MicroMachine yea the addition is correct. Given that you could start at ISO 12 and get up to ISO 6400 in only 10 frames...it'd probably be worth it to go every half stop instead of every full stop (getting 20 test frames and a more accurate ISO to pick from) \$\endgroup\$
    – OnBreak.
    Dec 6, 2018 at 23:55
  • \$\begingroup\$ Would another process involve comparing exposed frames to a grain chart? Or would the exposed frames grain depend on exposition/processing? \$\endgroup\$ Dec 6, 2018 at 23:57
  • \$\begingroup\$ For what purpose do you want to compare grain? Grain varies by manufacturer, exposure (under/over), processing (push/pull), and likely other factors. \$\endgroup\$
    – xiota
    Dec 7, 2018 at 1:01
  • \$\begingroup\$ I thought grain could be a way to determine ISO \$\endgroup\$ Dec 7, 2018 at 1:04
  • \$\begingroup\$ The procedure Hueco describes (basically extensive exposure bracketing) is the best way to determine the appropriate exposure setting (ISO) to use for a given developer and process. If you change the developer or process, you may have to adjust the exposure. You can just bracket normally because you should already be in the right ballpark after following the above procedure. \$\endgroup\$
    – xiota
    Dec 7, 2018 at 1:23

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