So why do you need polarized fishing glasses when you already have a pair of sunglasses you bought at the flea market?
Proper sunglasses should be near the top of your shopping list of fly fishing supplies.
If you are going to get serious about fly fishing (and protecting your eyes) you need a pair of good polarized fishing glasses so you can see the trout and steelhead below the surface. (A good hat also helps.) I have a friend who walks the banks of a western Oregon river in the summer and looks for summer steelhead. This is called “sight fishing.”
When you are able to spot the fish before you cast, you can present the fly to just the right spot. It saves a lot of time if you can see them.
There are many other good reasons for owning a good pair of polarized sunglasses, but let’s see what polarized sunglasses do first.
Normally light is non-polarized. Light waves vibrate in all directions.
When it hits a flat surface, the reflected light waves tend to become more horizontal or polarized in one direction. This phenomenon is what causes glare and it is many times brighter than non-polarized light. Water, snow, sand and the hood of your car are good examples of reflected polarized light.
Polarized fishing glasses have a vertical molecular orientation that absorbs light waves that come from other (mostly horizontal) directions.
Most polarized sunglasses are labeled at the store, but the best way to tell if they are polarized is to look through the lens while looking at a flat bright surface. Then turn the lens 90 degrees. You should be able to see a difference in the amount of light coming through the lens as you turn it.
To test for optical quality hold the lens away from your face, cover one eye and look thought the lens at a tile floor (or any object with lines). As you move the lens around the lines should be straight. If they are curved in any part of the lens then the lens is not optical quality.
Make sure the sunglasses protect your eyes from damaging UV light. Glasses with this protection will be labeled as such. This is important because UV light will damage both your cornea and retina.
Cheap polarized fishing glasses are made from ordinary plastic with a thin coating applied. If the cheap pair blocks some of the light (causing the iris to open) but does not give you UV protection, your retina will suffer more UV damage as a result. Cataracts and macular degeneration are just a few of the problems that can result.
A good pair is made with a sheet of polarized film between two pieces of glass or optical-grade plastic such as CR39 or polycarbonate.
Just like wearing a hat will block your eyes from the intense sunlight, wraparound sunglasses will block peripheral sidelight, giving you a better chance of seeing your trout.
Since all polarized sunglasses help in seeing below the surface, spotting fish is the goal here. This is where seeing the contrast between objects can be very helpful. Some colors are more helpful than others.
Amber: Good for most fly fishing. The increased contrast and clarity from this lens will help you spot trout. They absorb blue and will distort some colors. An amber or copper lens is good if you have only one set.
Gray: All-purpose, less color distortion, good for driving. They do not offer any added contrast to the subject. No special advantage in fly fishing.
Rose: They give you good contrast when viewed against a blue or green background. Good for fishing wide-open waters on sunny days. It blocks slightly more light than amber.
Yellow: Good for evenings, cloudy days and early mornings. It reduces blue light and distorts colors. A yellow lens allows more visible light in and gives good contrast to colors.
Mirror: Easily scratched, 100% cosmetic and not a good choice for fly fishing.
One thing to be aware of is that some polarized lenses may make reading liquid crystal displays hard to read. This would include some onboard instruments in your boat. This seems like a minor inconvenience to me when most of my fly fishing is walking the banks of a river.
If you are serious about fly fishing and protecting your eyes, you need a good pair of polarized fishing glasses. They will protect your eyes from damaging UV, cut down on the amount of direct light entering your eyes and eliminate the glare caused by reflected light, allowing you to see below the surface.
The color of the lens will be important also. For fly fishing for trout I would go with amber or a copper color.
And please don’t even think about those ten-dollar sunglasses at the flea market. Your eyes are worth way more than that.