This may explain perceived brightness of light. And if you can figure out what he's saying, let me know. Because whaaa?
Unfortunately, I'm coming up with no good links showing the correlation between the perceived brightness of a light that's hitting an object and the angle it's viewed from. If you have anything, let me know and I'll put it in this space. But if you want to see for yourself, use your phone on front camera mode and point at yourself as you stand in a room with the overhead on. Now spin in a circle and watch as the light seems brighter on your skin as it gets further behind you. Same light, same intensity but different perceived value.
A couple of examples of different shots from The Killing of a Sacred Deer. Part of the reason I included this is to show you the differences between a dirty over, a regular over (granted, we're looking over Nicole Kidman to see the over of Nicole Kidman in the mirror), a clean single, and a two shot. Not really groundbreaking stuff but it may be handy. I'm also including this because I finally saw this movie and I have to admit it was absolutely gorgeous. Not an easy movie to watch but absolutely beautiful