How do 3D Movies Work

This weekend Taylor and I went with a group of dads and daughters to see A Christmas Carol in 3D.  A popular question was, “so how do they do the 3D effect?”

We can judge depth because our eyes are about 2 1/2 inches apart, allowing each eye to have a slightly different view of an object.  The brain interprets these differing views, allowing us to note that the objects are at varying distances.

In a movie theater, the image is projected onto a flat screen, therefore we must show each eye a slightly different image, this is accomplished by using either polarized lenses (the better method) or red and green lenses (think headache).  Polarized lenses are, by far, the preferred method.  Typically, light radiates in all directions, polarized lenses filter the light so that it radiates in only one direction, with all of the light waves parallel to each other.

The 3D movie glasses use polarized lenses that filter the light 90 degrees apart for each eye, thus allowing each eye to see a different image.  Two movie projectors are then used to show the movie.   Each projector’s image is slightly offset on the screen simulating the distance between our eyes.  While wearing your polarized 3D glasses the movie looks clear and sharp.  If you take your glasses off the movie looks fuzzy with a shadow off to the left.  Your brain will fuse these views giving depth to the image.

An Interesting Experiment

If you take a friend’s 3D movie glasses and hold their left lens in front of your right lens you will see that no light gets through, turn the lenses perpendicular to each other and once again you can see through both lenses.

So How Was The Movie

The last 3D movie I saw used red and green glasses so it was great seeing a 3D movie that did not give me a headache.  The picture looked great and the 3D effects were well done, however that’s about it.  The chase scenes were way to long and really done mostly to show off the movie’s 3d effects.  Jim Carrey was good in his role as Ebenezer Scrooge and the movie stuck to the original book.  So the bottom line, it’s not a bad movie as a matter of fact they did a good job, however the only reason to see this movie, is to see the 3D effects.