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.
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.
To remove the rectangle I simply scratch it off with the edge of my knife. Like so:
Once removed it should look like this:
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:
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 |
Thanks for reading
Hamish
Wow. I had no idea. Thank you, Maestro!
Rob
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!
🙂
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I can’t wait to try this! Thanks Hamish.
Link me when you do Barry!
(Hope all is well with you and the family!)
Funny you commenting Barry, I was thinking of you last night as I made myself a hot whisky 😉
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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!
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!
Yup! Thanks, Hamish! I was just looking for a way to manually input the ISO on the Olymlus, and this could be the ticket!
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?
I don’t know myself. Some sticky back tin foil and black tape might be a solution…?
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
Hello Oshi,
Did you find a solution? I am also bulk loading some expired film which I like to use in a camera with auto DX (normally I use my Rollei 35) did you find some sort of stickers we can use or print and use???
@hamish, tx for the info
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?
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.
Thank you so much! For the isolation, I use nail polish. My wife is not very happy!
Haha, not a bad idea – though the drying time would cause me issues… I’d like the smell though! 😉
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 …
Not sure … Would you take a couple of photos of the cans and email them to me? [email protected]
They’re on the way now ….
After re-examination, I see that i was mistaken. Sorry to take up your time.
No probs, thanks for posting back on here to clarify – good luck with your recodings 🙂
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?
Yes, exactly that!
Exactly correct.
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Been nice if you oriented the canisters the same way as you went through the steps
If you find yourself frustrated at a modern 35mm camera automatically rewinding at 36 exposures rather than maybe squeezing out that extra shot or two, the DX coding also contains the number of shots on the roll – and there is a code for 48 shots (see DX codes on Wikipedia for details). Of course some cameras might decide to wind back at 36 anyhow and leaving rewind until the camera detects resistance may put stress on internal motors…
Very interesting, I did not know that!