December 13, 2016
A fist to the eye can help you get up in the morning, as well as teach us about optics.
Let’s say you put your alarm clock on a table across the room from your bed. You do this so that, when the alarm sounds, you’re forced to get out of bed. The trouble is that you may not be able to read the clock from this distance. How can a fist to the eye help?
A 2004 study by the National Eye Institute found that 42% of the US population aged 12 to 54 have myopia. That is, they are nearsighted. The most common cause is an elongation of the eyeball that causes light rays to focus on a plane in front of the retina. Distant objects become blurry.
Those of you familiar with lenses may know that closing a lens’s aperture will increase the depth of field. It is the same with the human eye. Put a small aperture in front of the eye, and its depth of field will increase, causing items that weren’t quite in focus to become clearly visible. And of course, this is where your fist comes in “handy.”
Close one eye and put your fist against the other. Open your fist until there is a small, round gap barely large enough to look through. And now your myopic eye may read the clock across the room.
Credit to Jim Sullivan of Schneider Optics for sharing the idea of using your fist.
Tags: Lens, depth-of-field