Do You Need Polarized Sunglasses?
Some manufacturers offer polarized sunglasses, others don't. You try them on in the store, and things look pretty much the same. So what's the difference, and why choose one or the other? Tinted lenses reduce light, mostly by absorbing it. Polarized sunglasses reduce light too, but they do it by using very narrow slots, kind of like a Venetian blind. Light vibrating in the same direction as the slot squeezes through; light vibrating in perpendicular directions is denied entry. Because reflected light usually has a different angle than its original source, a viewer can control reflected glare by controlling the angle of the polarized slots. Put on a pair of polarized driving glasses and tilt your head to one side. Abracadabra, the glare is back! Straighten your head, and it's gone again. Magic. Clouds reflect very diffuse light, so photographers use polarized filters to bring out depth and clarity in sky scenes. Fishermen use polarized sunglasses to help them see into water that otherwise would be blindingly opaque. Since highways and chrome reflect the hard sun, driving glasses are always polarized. |  |
But polarized sunglasses are not for everyone. Some objects appear less clear or distorted, especially LCD displays from electronic devices, which can become temporarily unreadable - not good if you're an air traffic controller. And polarized sunglasses tend to be more expensive. If you don't need to fight glare, you don't need to pay for it.