I find that brightness level 4 is a bit dull and brightness level 5 very bright, there is a huge difference between them. I'm certain that somebody else experiences the same problem. Can I set a brightness level between them? A terminal command? Hm. The issue I've had with brightness, right from the start, is that's the settings aren't fine-grained enough. I usually have it at 4, which is too dark, but 5 is way too bright.