DX code decoder & generator
The metal-and-black squares on a 35mm cassette tell your camera the film speed, length and latitude. Pick the values to see the exact contact pattern.
Silver = conductive contact, dark = bare. The top row after the common pad encodes speed; the bottom row encodes length and latitude. Re-spooling bulk film? Copy this pattern with foil tape so a DX camera meters correctly.
About this tool
The chequerboard of silver and black squares on a 35mm cassette is the DX code that tells your camera the film speed. Pick an ISO, the number of exposures, and the exposure latitude, and the tool draws the twelve-contact silver and black pattern the camera reads. This is handy when you re-spool bulk film into blank cassettes.
How to use it
- Choose the film speed (ISO) you want to encode.
- Set the number of exposures for the cassette.
- Select the exposure latitude value.
- Read the twelve-contact silver and black DX pattern the tool generates.
FAQ
Why re-create a DX code?
Bulk-loaded cassettes often have no DX pattern, so a DX-reading camera defaults to ISO 100. Painting or taping the correct pattern lets the camera set the right speed automatically.
What do silver and black squares mean?
Silver squares are the bare metal contacts that conduct, and black squares are insulated. The camera reads which contacts connect to decode the ISO, exposure count, and latitude.