Tutorials & Guides

Recoding the DX barcode on 35mm Film Canisters

The DX barcode on a 35mm roll of film is there, in part, to tell the camera it’s put into what ISO the film is. The majority of cameras from the mid 80’s onwards read this code automatically via either electrical or optical readers. Some cameras allow the user to override this code, but many, especially 35mm compact cameras don’t. If you only ever shoot film at it’s box speed, then this won’t cause you any problems but should you ever wish to push or pull your film shot in a camera without manual ISO override setting, then you might wish to recode the DX barcode.

The two things you will need are a sharp knife and a roll of electrical tape, preferably black, especially if your camera has an optical DX reader.

Recoding a DX barcode

Looking at the side of the film with the leading pointing up, it is the top row of silver/black rectangles that we are changing. The film in question is a roll of 200iso film that I’d like to recode to 400iso. If you look at the chart at the bottom of this article and compare 200 to 400 you will see I need to remove one black rectangle and add two.

Recoding a DX barcode

To remove the rectangle I simply scratch it off with the edge of my knife. Like so:

Recoding a DX barcode

Once removed it should look like this:

Recoding a DX barcode

The next step is to add two more black rectangles. To do this I cut a piece of black electrical tape to size and stick it in place like this:

Recoding a DX barcode

And it’s a simple as that! This film will now be read as 400iso by the camera it is put into.

The following table illustrates all the possible DX codes for coding ISO from 25iso to 5000iso:

25 iso
32 iso
40 iso
50 iso
64 iso
80 iso
100 iso
125 iso
160 iso
200 iso
250 iso
320 iso
400 iso
500 iso
640 iso
800 iso
1000 iso
1250 iso
1600 iso
2000 iso
2500 iso
3200 iso
4000 iso
5000 iso


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  • Reply
    March 8, 2014 at 10:23 pm

    Wow. I had no idea. Thank you, Maestro!

    • Reply
      March 8, 2014 at 10:26 pm

      Glad to be of service matey! re. Cinestill, if you peel back the cinestill label you will find a barcode of whatever the film used to be. You should be able to recode that to whatever you want!

  • Reply
    March 8, 2014 at 10:28 pm


  • Reply
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    […] and use that information to expose the film properly for its given ISO (tutorials here and here.)  Most cameras I use require me to set the film speed myself anyway, so I can just tell the […]

  • Reply
    December 9, 2014 at 6:16 pm

    I can’t wait to try this! Thanks Hamish.

    • Reply
      Hamish Gill
      December 13, 2014 at 10:25 am

      Link me when you do Barry!
      (Hope all is well with you and the family!)

    • Reply
      Hamish Gill
      October 17, 2015 at 5:24 pm

      Funny you commenting Barry, I was thinking of you last night as I made myself a hot whisky 😉

  • Reply
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    […] as 800. There is no built-in over-ride for the DX reading although Hamish Gill also describes (here) how to recode the DX barcode on a film canister to shoot the entire film at a different ISO than […]

  • Reply
    June 12, 2015 at 10:41 pm

    This is just so fantastic! I can’t wait to give this a whirl! I’ve been trying to figure out how to push film in my Olympus mju ii and this could be the ticket!

    • Reply
      Hamish Gill
      June 13, 2015 at 10:08 am

      Hi Simeon,
      Just a point of note… Pushing and pulling aren’t something done in camera. In camera you shoot the film at an “exposure index” or “ei”.
      If you had a roll of 400iso film, you might choose to shoot it as “box speed” or ei400.
      Alternatively if you shot that same roll at ei800, you would be underexposing it by 1ev, you then might choose to “push process” that film – or develop it for a longer period of time – in order to counter that underexposure.
      I’m sure you realise this, just thought it might be helpful in your path, good luck!

      • Reply
        June 13, 2015 at 10:51 am

        Yup! Thanks, Hamish! I was just looking for a way to manually input the ISO on the Olymlus, and this could be the ticket!

  • Reply
    Oshi Shikigami
    August 12, 2015 at 10:49 am

    I bulk load film. I use commercial reloading cassettes. These of course, do not have any encoding. I have a camera that is auto DX only. I would love to use the bulk loaded film in it. I keep reading of sticky labels, that confer the code, and attach to the cassette. However, I have yet to actually find someone selling these. Does anyone know of a current supplier of the labels?

    • Reply
      Hamish Gill
      August 12, 2015 at 11:36 am

      I don’t know myself. Some sticky back tin foil and black tape might be a solution…?

    • Reply
      Pieter Geloen
      December 13, 2015 at 9:12 pm

      If your canisters are metal, you can make your own DX patch.
      Scratch away (if there is any) all the paint till you see bare metal where the DX patch should be (check with canister that have DX codes)
      And then use this method to create your own ISO values.
      Also you should search the web (I believe the wikipedia page about DX codes has this) about how the second line is read. I think that lets the camera know how many exposures there are on the roll

  • Reply
    JJ Holdijk
    April 25, 2016 at 1:29 pm

    Does this work for developing services as well? So that when I turn in my roll of 400 ISO film recoded to 800 at the local pharmacy, it’s developed as an 800 film?

    • Reply
      Hamish Gill
      April 25, 2016 at 1:32 pm

      No, colour process is all the same timings – there aren’t many places that push/pull colour now.
      Shooting 400 colour at 800 is probably ok anyway, a lot of colour films will cope with its that sort of underexposure – not ideal, but should be ok.

  • Reply
    June 1, 2016 at 10:39 am

    Thank you so much! For the isolation, I use nail polish. My wife is not very happy!

    • Reply
      Hamish Gill
      June 1, 2016 at 10:40 am

      Haha, not a bad idea – though the drying time would cause me issues… I’d like the smell though! 😉

  • Reply
    Joey Harrison
    September 11, 2016 at 8:09 pm

    I was so glad to find this.
    Except that when I got set to hack a roll of Kodak Professional Tmax 100, I discovered that your bar code key for ISO 100 doesn’t match the one on the film canister. Then, just out of curiosity, I checked two other rolls. Kodak 400UC (C-41) and Fujicolor Super HQ 200 (C-41). The Fujicolor’s bar code matched the one on your chart but the Kodak 400 did not.
    So …

    • Reply
      Hamish Gill
      September 11, 2016 at 10:07 pm

      Not sure … Would you take a couple of photos of the cans and email them to me? [email protected]

  • Reply
    Joey Harrison
    September 11, 2016 at 11:18 pm

    They’re on the way now ….

  • Reply
    Joey Harrison
    September 12, 2016 at 1:09 pm

    After re-examination, I see that i was mistaken. Sorry to take up your time.

    • Reply
      Hamish Gill
      September 12, 2016 at 6:51 pm

      No probs, thanks for posting back on here to clarify – good luck with your recodings 🙂

  • Reply
    June 11, 2017 at 5:58 pm

    Pretty late question, but i just got myself a Yashica and wanted to know if I do the same with overexposing? I always shoot Portra 400 at 200 so i have to change the DX Code to 200 right?

    • Reply
      Hamish Gill
      June 11, 2017 at 6:07 pm

      Yes, exactly that!

      • Reply
        Oshi Shikigami
        June 11, 2017 at 9:44 pm

        Exactly correct.

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