[aisamu]

A simple method that I use to demonstrate that: point a phone's camera at the screen+surroundings.

Then it's easy to adjust the screen's brightness/turn on lights until the screen is not overexposed/the environment is not underexposed.

[jonpurdy]

As a photographer, as well as a Technical PM who spends all their time on a computer, and a non-zero amount of time optimizing my setup, and someone who has taken photos of computers and done exactly this to get the exposure correct: I don't know why I didn't think of doing this on a daily basis!