I had a bunch of film cameras that would auto set the iso and auto advance the film. How it did this is 35 mm film had the iso and length encoded on the canist

I had a bunch of film cameras that would auto set the iso and auto advance the film. How it did this is 35 mm film had the iso and length encoded on the canister as “dx” coding. There were a bunch of sensors in the camera that measured if one of the squares conducted or didn’t. It’s kinda a neat solution and worked well. https://en.m.wikipedia.org/wiki/DX_encoding https://en.m.wikipedia.org/wiki/DX_encoding And a typical reader. https://upload.wikimedia.org/wikipedia/commons/1/1c/Canon_eos30_dx_code_reader.jpg https://upload.wikimedia.org/wikipedia/commons/1/1c/Canon_eo...