How to Not Get a Headache Watching Avatar or Any 3D Movie
I was just sent an email the other day with a link to this guide on Shadowlocked (via Gizmodo) that explains "How to avoid getting a 3D headache while watching Avatar." It doesn't happen to me, but apparently some people get headaches from watching 3D, especially over two hours of it (since Avatar is 162 minutes long). They came up with a very simple "guide" and explanation behind why you might be getting headaches. While the focus is on Avatar, this tip can be used while watching almost any 3D movie to prevent headaches and other issues. It's a simple idea that makes a lot of sense. Check this out even if you don't get headaches.
They explain that Cameron's 3D in Avatar is not the gimmicky "jack-in-the-box" pop out 3D, instead it's just like normal cinematography with shallow depths-of-field meaning some of the frame is heavily out of focus. The problem is that some people want to look at this part of the frame, their eyes either wander there or are attracted there for some reason, but looking at that "out of focus" part is bad (see the photo above). You can read Shadowlocked for a much better explanation, but the tip is to keep your eyes focused on the important parts of the frame that Cameron has chosen. And if you do that, you won't get any 3D headaches (in theory).