By their very nature, digital cameras are always measuring the amount of light hitting their sensors and use that information to adjust exposure times. But film cameras require adjustment to get the proper exposure for a particular setup and even swapping lenses can change that. Traditional calibration equipment is expensive, but this DIY film camera tester kit is an affordable alternative.
To perform the tests needed to calibrate a film camera, you want a precision light source and an accurate exposure sensor. An exposure sensor alone does work for some tests and the kit has provisions for those, but a calibrated light source helps to configure light meters built into cameras. This kit provides both light source and exposure sensor options, with different modules available for common camera types. The full kit allows for both time-based and light-accumulation calibration tests for film cameras.
The key component is an Arduino Nano board, which monitors the connected exposure sensor. Through a custom shield PCB, it displays the exposure results on a 20×4 character LCD and a control interface board lets the user set up each job. For the tests that require it, there is a calibrated light source that provides highly repeatable output from one exposure to the next. The kit on Tindie is out of stock right now, but this project is open source so users can build their own Film Camera tester