I was very pleased to find out about the existence of “binocular soccer”. It’s a whimsical, silly romp, another manifestation of that distinctly Japanese sense of humor. Check out “human Tetris” for another delight in the same genre. The inherent difficulty of playing this game has much to do with fundamental principles of optics.
Why is it so hard to kick the ball? Because your eyes perceive the image of the ball to be in a different location than it actually is. Binoculars are basically two telescopes mounted side by side. Each barrel in a pair of binoculars has two lenses — an objective lens (the one closest to the object being viewed), and a second lens called the eyepiece.
Binoculars magnify relatively distant objects. This is how it’s done: The objective lens gathers light coming from the object being viewed. This light is refracted so that an image of the object is formed inside the focal length of the eyepiece. This image is very small, but because it forms inside the eyepiece’s focal length, the eyepiece acts just like a magnifying glass. Looking through the binoculars, your eyes perceive a final enlarged image in front of where the object actually is. Notice how the players always seem to miss the ball by kicking too far in front. That’s where they see it.
I realize this game is intended as comic relief, but it would be scientifically interesting to establish a professional league and see just how the athletes in this newest exciting sport learn to calculate and compensate for the optical sleight of hand.
Adam Weiner is the author of Don’t Try This at Home! The Physics of Hollywood Movies.