Polarized sunglasses are an absolute necessity for every fly angler. Normal sunglasses are better than no sunglasses and they reduce eye strain but they do nothing to help you see fish. When you are hunting for fish, the only lenses that will do you any good are the Polarized variety.
How they work:
(a highly un-scientific explanation)
Light is reflected from water surfaces horizontally. Polarized lenses have horizontal striations that block almost 100% of those waves. They filter the light, greatly reducing eye strain as well as glare from the water surface – this means you can see deeper into the water and spot more fish. Any sunglasses you intend to use for fly fishing should be labeled as “Polarized” and made by a reputable company. Polarization is not created equal so ask permission to take the glasses outside and look at the clouds. You should be able to clearly see depth in the cloud formations and distinguish the edges of the cloud-banks.
What to look for in a sunglass frame:
Get a frame with great side coverage. This means very wide temples (the temple is the piece that goes over your ear) that block a lot of light. They should wrap around your face and fit snugly. You will see the advantage of this by cupping your hands around the bill of your hat and your sunglasses. By blocking more light you are able to see everything in higher contrast.
Lens color:
When it comes to the color of the lens things get specific real fast. For salt water a light gray or blue lens works very well. For most fresh water conditions a bronze, copper or rose lens is the choice. For low light conditions, yellow or orange works best. Light transmission is also important. Light transmission is how much light is allowed through the lens or, in other words, how dark the lens is. A lens that is too dark does not permit enough light for you to distinguish the fish from the river-bed so be sure you don’t pick a lens that is too dark.
Lens color, Strike Indicators & Water Color:
Rose lenses – fluorescent orange indicators will be the most visible – this color cuts through green water very well.
Blue and Grey lenses – fluorescent orange and fluorescent pink indicators will be the most visible – these lenses cut through turquoise water very well.
Bronze or Copper lenses – orange, fluorescent orange and fluorescent pink indicators will be the most visible – these lenses help you see into most fresh water colors.