I bought a bag of unbranded film. It was 60 dollars for 15 rolls so I couldn’t pass up. But obviously I don’t know the exposure or the ISO. Does anyone have a suggestions on the ISO/ASA I should shoot on? I was thinking 250 but I’m new to film photography.


4 Answers 4


Use one of the rolls for testing.

Choose a variety of scenes, and take several shots of each, with a range of settings for each scene (the same range for each scene) and make a note of the settings.

Get the film developed and see which settings were generally the best.
You may be able to get an idea of the ISO from the grain of the prints too.

  • \$\begingroup\$ Clearly the best suggestion. After the film has been developed, chances are also relatively high that the film type is imprinted along the border of the negatives (outside the sprocket holes). \$\endgroup\$
    – jarnbjo
    Sep 25, 2023 at 7:13
  • Shoot one film at ISO 200 (as a nice middling speed)
  • Include some test shots at known EV; your phone is a good enough meter here.
  • Get the film developed.
  • Check if the test shots are correctly exposed. Correct if they're not.
  • Hope all the other films in the bag are the same speed (this may be a big ask. Do they all look the same?)

There is no EI setting that is sure to be a good fit for any/all film of unknown ISO. First thing you should do is ask the seller if possible. Then, you need to use trial and error - you can start with 200 and see how the results turn out. Assuming (and that's a big assumption) that all the rolls are the same ISO, then you would adjust the EI as appropriate. If you wanted, you could do what's called a "clip test", where you expose only a couple of frames first, and get a (pro) lab to clip off and develop just those first few exposed frames - this would allow you to make adjustments before you've shot through an entire roll of film. Also - if you're lucky - the film may have edge markings that give away its true ISO value.

If you are new to film photography, then I would suggest not buying cheapo film of unknown ISO just to save money. You will probably waste more money in the long run - paying for film and development and potentially getting no useful results and not really learning a whole lot. Buy the cheapest fresh C-41 film you can find (or B&W if you intend to develop yourself) from a reputable brand and reputable retailer. All hobbies are going to involve some cost unfortunately, and this is the cost of getting into film photography.


Some ideas.

Does the cartridge have big squares on it? Some chrome natural metal (conductive), some with paint on it (Non-conductive). It is a type of "barcode" which identifies the ISO speed. Take a look and see if you can identify it or post an image so someone can identify it. If your camera has some electric connectors where you put the film, it will probably automatically define the ISO speed.

The code can also be located in the film itself.

35 mm film Dx Code

enter image description here

From Wikipedia https://en.wikipedia.org/wiki/DX_encoding

Does it have any name on it? There is a chance they have a name similar to some films that had specific name prefixes that reference the speed. For example, if I recall correctly, on Black and white film "Tri-x" was ISO speed 400, and "Pan-x" was ISO 100. So if the name is something like TrixBanana, it is probably ISO 400.


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