Friday, March 20, 2015

Physics Life Hack Number 1 - Hack Your Eyes

Mathlete sees clearly with this physics life hack
A simple trick can help you see clearly  - with physics!

Age has not been kind to my eyesight or my memory. That means that while I now need glasses to correct for the farsightedness of the increasingly inflexible lenses in my eyes, I often forget where I put them (the glasses, not my eyes). That can be a real problem for someone whose entire job consists of reading.

Fortunately, we at Physics Buzz would like to share a life hack for all the optically challenged and forgetful folk like me.

If you don't have glasses handy, you can significantly improve your vision with this cool manuever demonstrated by Physics Buzz's own blogger, Mathlete.

All she's doing is curling her fingers to make a tiny hole to peek through. Like this . . .

Impromptu pinhole glasses.
Essentially, she's blocking most of the area in front of her eye to turn her it into a human version of a pinhole camera.

That's good because the distortions that hamper most people's eyesight have to do with problems with our eyes' lenses and corneas. In my case, the lenses have stiffened with age, and they can no longer focus on objects nearby. Mathlete suffers from an astigmatism, which means the focusing elements in her eyes aren't perfectly symmetrical and things that should focus to a point are smeared out in one direction.

Pinhole cameras don't need lenses. Everything is in focus, all the time, when you're looking through a pinhole. And the smaller the pinhole the better.

Lots of light, but limited focus depth of a cell phone lens.
Here are two pictures showing the difference using my cell phone camera. 

In the first shot, I took a picture in the normal way - by letting the camera adjust the focus. You can see that the image is focused on the coffee cup in the foreground. The portrait of my daughters in the background, however, is fuzzy.

I took the second picture by poking a hole in a piece of paper with a pin and taping it in front of my cell phone camera's lens. The image is a bit grainier because there's less light getting through pinhole than there was for the lens without the pinhole in front. But my daughters are in just as good focus as the coffee cup.

Pinholes limit the light that gets through to the camera, but everything is in focus.

So why don't we have pinholes for eyes instead of the complicated lenses and other bits that so often let us down with age or congenital defects? Because you need lots of light to be able to see through a pinhole at all.

Mathlete's finger-based pinhole is fine in the bright light of day, but she wouldn't see a thing in low light. That would have been a problem for our ancient ancestors who had to be on the alert for predators that prowled the night. And a bear is pretty easy to identify as a bear, even if the focus is a bit off.

(Incidentally, squinting helps poor-sighted people for the same reasons as pinholes, but I find that the finger-based pinhole works better. Compare the two methods to, ahem, see for yourself.)

So if you find yourself without your glasses but plenty of light, you can make do with our little physics life hack. And you'll look really cool doing it too.

You're welcome.


  1. I don't think squinting works for the same reason. Squinting puts pressure on the eyeball and changes the shape of the lens as well as the distance between lens and retina.

  2. That's the same explanation I heard as a kid, but I don't believe it anymore. People squint regardless of their vision issue. But if increasing the the pressure is the reason they squint, then it should only work for one specific type of vision problem (either short-sightedness OR farsightedness OR astigmatism).

    If instead it improves focus by reducing the effective diameter of the lens, then it would help all people to see a bit better.

    Finally, eyes are very sensitive, but when I squint, I don't feel any pressure. When I try to exert pressure on my eyes in other ways, it makes my vision worse and hurts.

    So I would put the pressure explanation for squinting in doubtful category at least.

  3. I cant believe how well that worked!!