How do 3d glasses work?

How come those disney real d 3d glasses don't work on regular 3d images?

• Like the ones where the lenses are all black? how come they dont work on other 3d images and stuff?

• Answer:

  that's SHUTTER technology. When you look at an image on your computer screen, where it was set up to be 3 D, without the glasses, it looks like two images are there, a little offset from each other. But in reality, only ONE image is on the screen for one fiftieth of a second. Then it disappears and the other one is on the screen. Back and forth like that. Our eyes, however, only refresh at one thirty-FIFTH of a second (1/50th versus 1/35th) so 1/50th is TOO FAST for our eyes too notice. The glasses are polarizing at that same rate. Every 50th of a second, one lens is "open", a fiftieth of a second later, the other lens is open. So you only see ONE of the images in your left lens and the other image in your right lens. You never notice any flicker. Obviously this can only work on something that flashes in and out of visual existence. Other 3D things, the left and right image are there ALL THE TIME.