I went out to the beach a couple weekends ago and thought I was so clever timing the shutter and setting it to precisely 1/6 second. Took a couple shots.

Then I realized I was shooting waves and needed 1/250, so I was back to the old “pick highest speed and hope it’s pretty close”

I want to know why hasn’t someone made a shutter tester from a scrapped digital camera. Seems you should be able to quantify exposure fairly accurately with an imaging sensor