When the delicate timing mechanisms of the shutter begin to deteriorate, the shutter times can change, and this results in incorrect image exposures. Sometimes the inaccuracy iis substantial and clearly noticeable, but at higher shutter speeds, it is difficult to tell the difference between 1/500th of a second and 1/1000th of a second. However, to the film that difference is substantial.
When doing camera shutter repair, having a way to measure the timings can help give you insight into what might be wrong, and also lets you test as you tinker with things to see if you're making things better or worse, and how close you are getting to your desired shutter accuracy. It's an invaluable tool for any aspiring camera repair tinkerer to have.
This project is based on the PIC18F2525 microcontroller, and an HD44780 16x2 character LCD. It uses an OPT101 photodiode with integrated trans-impedance amplifier for the sensor, and a 1 watt red LED for the light source.