>>4202968>I have a handheld lightmeter, I'm thinking of using it for the photos and writing down the measurements of both the handheld lightmeter and the internal one to compare them laterI have a Canon FTb QL with a 1.5V battery and I wanted to see what I was getting so I did a light meter test similar to your suggestion and in line with this article
https://www.35mmc.com/17/05/2023/is-my-old-light-meter-reliable-a-little-test-and-the-results/looks like my Canon is underexposing by 2 stops with the current battery and it's a good thing I checked because I just finished a roll of Tmax 400 in it today that I'll have to compensate for in development.