Why is it that 35mm film is always supplied in a small plastic canister, when the film itself is enclosed in a hard, opaque carapace itself. Now, potentially for high-sensitivity films like Ilford Delta 3200 this would make sense, as it comes with an (ostensibly) light-proof canister. But then again, lower sensitivity films (eg: Neopan 100) is supplied with a light translucent container.

But then again, it seems likely that there is a good reason--perhaps to keep out excess moisture, or other potential harmful airborne substances.


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    So that we have a convenient place to put things like paper clips, small screws, etc.
    – Evan Krall
    May 23, 2011 at 9:08
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    They are perfect for coin storage. The top canister cap also works perfectly as a spare cap for Pentax DA 40 mm f/2.8 Limited.
    – sastanin
    May 23, 2011 at 9:20
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    @Evan and @jextee - Even better as salt and pepper holders for camping. :)
    – Joanne C
    May 23, 2011 at 12:43
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    What is the point of film when we have memory cards?
    – dpollitt
    May 23, 2011 at 13:37
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    @Evan Krall - I can certainly fit a lot of memory cards into a film camera, it's making them do something useful that's the hard part.
    – Fake Name
    Sep 7, 2011 at 2:00

6 Answers 6


I think, like you said, the canisters are made for protecting the film from external influences. The plastic casing of the capsules is not completely shut. Dust, small water drops and light might get inside without an extra casing.

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    yup, helped when I got caught in a dust storm some 25 years ago. Lens destroyed, film was fine (camera somehow survived).
    – jwenting
    May 23, 2011 at 11:24
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    As well as protecting from dust and moisture, bear in mind that the film casing is rather fragile. Quite gentle crushing can crack the seal and fog the film. If the film is in a soft plastic canister it can take much more punishment.
    – Max Sang
    May 24, 2011 at 16:11

If you ever used a reloadable film cassette, then you know how easily those things fall apart. When you take apart a one-use cassette in the darkroom, you have to use a church key or special tool to take it apart without hurting yourself. You end up with a couple pieces of bent metal in the process. A reloadable cassette will come apart just by pulling the top off — it is in fact harder to take the top off a canister than it is to disassemble a reloadable cassette, especially once you've used it a half dozen times.

  • I've used a Mamiya 645 with a 220 and 120 film backs, and of course, the film comes pretty much naked, except for the paper leader/ trailer. (not that I'm all that careful when it comes to re-loading / spooling it into the camera. That said, I meant the little plastic canisters that the film cassettes come in, rather than the cassettes. Still, thanks for the interesting post.
    – C. Storey
    May 24, 2011 at 9:53
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    Hm, I was saying that the canisters are necessary because the cassettes fall apart so easy. May 24, 2011 at 14:37

This was the subject of a long-running letter thread in the Guardian newspaper a couple of years back. You'd be amazed what people use them for. :)

  • Unfortunately the link died.
    – Michael K
    Jun 13, 2016 at 12:50
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    Thanks for letting me know - I've updated that now to a working link. Jun 13, 2016 at 13:24
  • This is why we discourage link-only answers - would it be possible for you to summarise the thread in your answer so that we're not dependent on the vagaries of the Internet in the future?
    – Philip Kendall
    Jun 13, 2016 at 15:06

One function of these canisters is that they prevent moisture condensation on films removed from a fridge or cold outdoor environment. Water condensation is a big problem, because wet emulsion swells and becomes sticky. The film can easily become unusable. Wet film, especially in the past was an excellent substrate for fungus. Swelling, sticking and fungus easily damage the film...

Films are also sensitive to various gasses, so this is protection against that as well.


You can use the translucent ones as diffusers for pop-up flashes. Take the lid off, cut a notch out of one side, place it on the flash and put the lid back on. Voila! Softened flash, no more Coccoon shots.

  • It should be noted that this doesn't directly diffuse your flash -- it sprays it in more directions so it's more likely to bounce off ceilings and walls.
    – Evan Krall
    May 23, 2011 at 22:11
  • From the Chambers Online Dictionary: diffuse verb (diffused, diffusing) tr & intr to spread or send out in all directions. May 24, 2011 at 7:34
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    Fair enough. This doesn't directly soften your flash -- it diffuses it, and when near reflective surfaces (like walls and ceilings), the reflections soften it. Try this out in the open, and you'll find that nothing really happens except your flash has to use more power to hit your subject.
    – Evan Krall
    May 25, 2011 at 6:12

IR film has/should to be loaded/unloaded in complete darkness, so thus the film needs to be transported in canisters until such a time as you need to use it - at which point you have to load the camera in a darkened room, or use a portable dark bag.

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    That is only Kodak HIE (now discontinued). Other IR film stocks don't have this issue because they have the anti-fogging layer it was missing.
    – cabbey
    Sep 7, 2011 at 17:13

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