Simple and works
All other lux meters I installed and uninstalled, with their many positive reviews, started free, then sometimes it was very obviously inaccurate. Eventually it would boil down to “it would be accurate if you buy this or that and add it on top … now you could make one yourself from newspaper, but it will not be as accurate”!! I used this to measure how much light will hit my eyes when I read a book, vs read from browser on monitor, vs read dark theme article on monitor. It gave me perfect comparison of each for free. Reduce monitor brightness and contrast, all show how much difference they make.