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
37 Comments
Rob
March 8, 2014 at 10:23 pmWow. I had no idea. Thank you, Maestro!
Rob
Hamish
March 8, 2014 at 10:26 pmGlad 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!
Rob
March 8, 2014 at 10:28 pm🙂
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Barry
December 9, 2014 at 6:16 pmI can’t wait to try this! Thanks Hamish.
Hamish Gill
December 13, 2014 at 10:25 amLink me when you do Barry!
(Hope all is well with you and the family!)
Hamish Gill
October 17, 2015 at 5:24 pmFunny you commenting Barry, I was thinking of you last night as I made myself a hot whisky 😉
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January 2, 2015 at 8:55 pm[…] 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 […]
Simeon
June 12, 2015 at 10:41 pmThis 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!
Hamish Gill
June 13, 2015 at 10:08 amHi 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!
Simeon
June 13, 2015 at 10:51 amYup! Thanks, Hamish! I was just looking for a way to manually input the ISO on the Olymlus, and this could be the ticket!
Oshi Shikigami
August 12, 2015 at 10:49 amI 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?
Hamish Gill
August 12, 2015 at 11:36 amI don’t know myself. Some sticky back tin foil and black tape might be a solution…?
Pieter Geloen
December 13, 2015 at 9:12 pmIf 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
Barry
April 8, 2019 at 8:42 pmHello 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
JJ Holdijk
April 25, 2016 at 1:29 pmDoes 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?
Hamish Gill
April 25, 2016 at 1:32 pmNo, 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.
Alexander
June 1, 2016 at 10:39 amThank you so much! For the isolation, I use nail polish. My wife is not very happy!
Hamish Gill
June 1, 2016 at 10:40 amHaha, not a bad idea – though the drying time would cause me issues… I’d like the smell though! 😉
Joey Harrison
September 11, 2016 at 8:09 pmI 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 …
Hamish Gill
September 11, 2016 at 10:07 pmNot sure … Would you take a couple of photos of the cans and email them to me? [email protected]
Joey Harrison
September 11, 2016 at 11:18 pmThey’re on the way now ….
Joey Harrison
September 12, 2016 at 1:09 pmAfter re-examination, I see that i was mistaken. Sorry to take up your time.
Hamish Gill
September 12, 2016 at 6:51 pmNo probs, thanks for posting back on here to clarify – good luck with your recodings 🙂
daniel
June 11, 2017 at 5:58 pmPretty 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?
Hamish Gill
June 11, 2017 at 6:07 pmYes, exactly that!
Oshi Shikigami
June 11, 2017 at 9:44 pmExactly correct.
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September 28, 2019 at 9:44 pm[…] I love that I have the option to manually change the ISO on a shot by shot basis (yes, you can hack DX coding, but it’s a bit of a faff). I’d love the scale to go one more stop to 800, but then I suppose […]
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Clifford Gwinn
May 5, 2020 at 4:01 pmBeen nice if you oriented the canisters the same way as you went through the steps
Bob Janes
April 20, 2021 at 9:14 amIf 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…
Hamish
April 20, 2021 at 4:01 pmVery interesting, I did not know that!