Remember the last time you went to a movie theater to see a movie? You were surrounded by technology! From the gigantic screen to the incredible sound system, the goal of all this technology is to fill your senses.

Have you ever thought about everything that happens inside a movie theater? How does the picture get on the screen? How does the sound system make the explosions so earth shattering? And what will we see in the future in the new digital movie theaters? Let's all go to the movies for a behind-the-scenes tour.

First, a word from your brain...
The human brain is an amazing thing. Movies would not be possible if the human brain did not have something called "persistence of vision". Here's how it works. Think about what happens when you move your hand in front of your face. You see your hand moving with your eyes. This is smooth, continuous motion. Here's the interesting thing. Let's say you have a camera that can take 24 still photographs of your hand every second. Now you look at those still pictures rapidly, one right after the other. Your brain doesn't look at them as still images anymore. Your brain will reassemble the still images into a single, moving scene.

Each of the images is slightly different from the next. Your hand moves just a tiny bit from image to image. If you have 15 or more subtly different frames per second, your brain combines them into a moving scene. Fifteen per second is about the minimum possible -- any fewer than that and it looks jerky.

Without persistence of vision, movies would not be possible, and neither would TV. Movies use 24 frames per second. TV uses 30 or 60 frames per second. To your eyes, it looks like smooth, continuous motion.

Movie film

(Most) Movies Use Film

There are two kinds of movie theaters today - analog and digital. Digital movie theaters are still very new, and there are only a few hundred of them in the United States. There are tens of thousands of analog movie theaters and they all use film. When you go to watch a movie, chances are that your theater is using film and film projectors to put the movie on the screen.

Digital cameras and video cameras are so common today, you may have never seen film. Film is nothing but a thin piece of clear plastic with color images on it. You can shine a light through the film, and the image on the film appears on the screen. Along both sides of the film, there are sprocket holes. The film used in most theaters is 35 millimeters wide. If you look at a piece of film, you can see that there are four sprocket holes for every image on the film.

It takes a LOT of film to show a movie. A movie projector shows 24 frames of film every second. There are 16 frames per foot of film. If you do the math, you can see that it takes more than two miles of film to hold one two-hour movie!