I came across a pretty interesting article the other day about why 3D movies give some people headaches and some of the technical issues with “faking out” your eyes and brain.
One of the biggest issues, as this article states, is the focus/convergence issue. When you focus on things, not only do each of your eyes lenses focus, but your eyes also converge and diverge (rotate toward and away from each other).
I brought up the focus/convergence issue when I saw Avatar in 3D. I noticed it right away. Your brain tries to fight your eyes. You’re being shown objects in “3D” that keep changing (size, position, depth, etc.), but you’re staring at a single screen that isn’t moving. Now, if you’re able to subconsciously “ignore” this problem, you generally shouldn’t have any problems watching stuff in 3D. I was very aware of what was happening, so I choose to not think about it or I’d drive myself crazy.
The other big thing for me is how they handle depth in a 3D movie. To me, it’s very strange to have a “3D depth-of-field” forced on you. When you focus (in reality) on something in the distance, closer objects blur. You can change that focus to something closer and the distant objects will blur. You can’t do this in a 3D movie. You’re forced into what they want you to focus on.
Now, you could argue that this is the same thing as a 2D movie (as in, depth-of-field), but in a 2D movie, you don’t have the illusion of being able to refocus to look at different object in the scene. This is a task that is exhausting to your brain and eyes over 2 hours.
In a regular 2D movie, the depth information that you get from a well-shot scene using depth-of-field is more than enough to understand the dimensionality of the scene. Your brain generally just buys it. You understand the scene. You understand what is close and what is far. The unnatural strain comes from the filmmakers using depth-of-field in a 3D film, and you wanting to focus on an object that is in front of others in the scene that is out of focus.
I, for one, find the 3D stuff in movies to be somewhat interesting. I think it’s fascinating that it works as well as it does. However, can we please not pretend this is ready for our living rooms?