Blog post (The argument isn't actually Ebert's)
Bottom line: 3D films are asking you to focus your eyes at one distance (the actual distance between your eyes and the physical screen) while converging your eyes at another (to the distance between your eyes and the simulated 3D object you're looking at.
It's not a bad point, and one I've thought of before.
Actually, Magic Eyes work on the basis of HUGELY exaggerating this effect. To get a Magic Eye to work, you of course have to have the image in focus, but your eyes are converged as though they're looking at something about twice as far away.
This might be why it seems to me that both Magic Eyes and 3D movies look far more vividly three dimension to me than the real world does. I think I one time linked to a product that uses mirrors in a helmet or visor to simulate what it'd be like to have your eyes a foot or two apart rather than the 5 or so odd inches they are now. It supposedly makes the world look exaggeratedly three dimensional.
Anyway, I'm skeptical that this is much of a show stopper. I am near sighted and wear glasses, and the effect is basically that I have only one focal length for my eye. I can't focus much. Anything that's greater than about 2 feet from my eyes is essentially "at infinity", meaning that they're all focused almost the same way (and if there is any difference for how I focus on things, it changes less and less the farther away they are). Meanwhile, anything closer than 2 feet is simply out of focus (unless I take my glasses off)
I will say I got a headache once from watching a 3D film. It was actually the cartoon short (something about Chip and Dale) before Meet the Robinsons. I don't quite remember what the issue was, but it might have been that too many layers of simulated depth were all in crisp focus at the same time, which made it difficult to focus on any particular thing.
Whatever the cause was, I think people who make 3D films now understand the issue better because I haven't had that problem again (the short was actually really old, possibly even made when Walt Disney was still alive)
Bottom line: 3D films are asking you to focus your eyes at one distance (the actual distance between your eyes and the physical screen) while converging your eyes at another (to the distance between your eyes and the simulated 3D object you're looking at.
It's not a bad point, and one I've thought of before.
Actually, Magic Eyes work on the basis of HUGELY exaggerating this effect. To get a Magic Eye to work, you of course have to have the image in focus, but your eyes are converged as though they're looking at something about twice as far away.
This might be why it seems to me that both Magic Eyes and 3D movies look far more vividly three dimension to me than the real world does. I think I one time linked to a product that uses mirrors in a helmet or visor to simulate what it'd be like to have your eyes a foot or two apart rather than the 5 or so odd inches they are now. It supposedly makes the world look exaggeratedly three dimensional.
Anyway, I'm skeptical that this is much of a show stopper. I am near sighted and wear glasses, and the effect is basically that I have only one focal length for my eye. I can't focus much. Anything that's greater than about 2 feet from my eyes is essentially "at infinity", meaning that they're all focused almost the same way (and if there is any difference for how I focus on things, it changes less and less the farther away they are). Meanwhile, anything closer than 2 feet is simply out of focus (unless I take my glasses off)
I will say I got a headache once from watching a 3D film. It was actually the cartoon short (something about Chip and Dale) before Meet the Robinsons. I don't quite remember what the issue was, but it might have been that too many layers of simulated depth were all in crisp focus at the same time, which made it difficult to focus on any particular thing.
Whatever the cause was, I think people who make 3D films now understand the issue better because I haven't had that problem again (the short was actually really old, possibly even made when Walt Disney was still alive)

