Well in the case of Lord of the Rings, the lighting was at a level that made it so you could reasonably see about what the characters would already be able to see after their eyes adjusted to the dark. So it doesn't really cause any discrepancy, it just makes it so the cameras could see things as well as the people there would and makes the whole thing a lot more watchable.

It's not even that dim either, it's just drowned out by the light pollution of our own galaxy.

I like the description given by the cinematographers for the lord of the rings when asked where the light was coming from in the night scenes. "The same place as the music" was their answer.