While doing a bit of searching i came accross this and thought it was worth putting up
Sunglasses: more than meets the eye
MOST anglers wear sunglasses most of the time, even when they’re not fishing. Actually that could extend to most people, these days. There are a lot of pairs of sunglasses out in the world. So what sunglasses are the best?
Kimberley fishing guide Robert Vaughan always tells his clients to bring polarised sunglasses, and they always make agreeing noises about it, he says, but he’s never surprised when they turn up with non-polarised sunglasses. The fact simply is most people don’t know whether or not their sunglasses are polarized and, for that matter, they don’t get why they should be for fishing, so they don’t care.
Until the angler alongside you is seeing all the fish and the rocks and gutters and every other feature essential to fishing success, and all you’re seeing is the water and what’s above it, you won’t get it. But by the time you’re actually out there fishing, it’s too late to start thinking about it. Here’s why you need the right sunglasses right now, and why they need to be polarised.
There’s no trick photography here, it’s the real thing: two photos taken as the eye sees it and then the same scene captured with a polarised sunglass lens held in front of the camera lens – just as the eye would see the scene when wearing polarised sunglasses.
Polarising has only been around in optics for about 70 years, and was made famous by the Polaroid brand, which is what a lot of people still call any brand of polarised sunglasses. Pretty successful marketing that, for a product that is still so misunderstood.
The essential ingredient is a film of transparent material that blocks light in the horizontal plane, but not the vertical plane. In the fishing environment most of the glare we have to contend with is that which is reflected off water, and it comes at us in the horizontal plane. The guy who first came up with a synthetic material that could serve the purpose of blocking that glare was Edwin Land, a prolific American inventor. He was 20 at the time, and went on to found the Polaroid company.
Reflected light, our fishing problem, is always polarised in the same plane as the reflecting surface. This is good news for sunglass makers, because to be effective for fishing, they know it’s glare in the horizontal plane they have to contend with; so they align their polarising material to block light in the horizontal plane, and the job’s done. When you buy polarised sunglasses, you get that; they will block light in the horizontal plane. In that respect, the cheapest pair of polarised sunnies is every bit as effective as the most expensive pair! But there’s a bit more than that to making sunglasses.
Back there somewhere I mentioned a ‘transparent’ polarising material. So could polarised sunglasses be clear? No – the end result dictates that not all of the light gets through, so it’s inevitable that the lens will appear dark, and in fact more than 50 per cent of the light will be blocked. Most sunglasses have tints added, and some are also photochromatic, which varies the tint according to the UV light intensity. Sometimes, anyway. I’m not a fan of photochromatic lenses, because the chemical process that darkens them relies on activation by UV light, not visible light. When you’re in the car the windscreen blocks out lots of UV light, so the photochromatic lenses don’t darken enough for my liking when driving. That’s why even photochromatic lenses always have tints added.
The maximum polarisation, for what it’s worth, occurs when the sun is about 37 degrees up from the horizon. But even without glare, polarised sunnies selectively remove reflections from things like clouds, and the sky itself. The only downside to polarised sunglasses when fishing is that some other things are polarised, like the LCD screens on some marine electronics for instance, and if you’re not looking at them with the screen polarisation and the sunglass polarisation in the same plane, the screen will appear to black out. The light simply can’t get to your eyes.
This is also a quick way to check is a pair of sunglasses is polarised: take a pair that you know is polarised and while wearing one pair, look through the other pair; then rotate the second pair through 90 degrees. If the light transmission severely decreases, the second pair is polarised too.
On to other things about polarised sunglasses. The polarising chemical film that does the job has to be applied to the lens material. To protect it in sunglasses, it is sandwiched between either two sheets of glass, or two sheets of plastic. This laminate can of course delaminate, a particular problem with the earlier attempts at making polarised sunglasses, but one that is still evident today. Washing the sunnies in hot water is a good way to have it happen.
Glass is the most scratch-resistant, and heaviest, lens material. If combined with a lightweight frame that fits your face well, it’s the best for fishing, because it is tough and easily cleaned. But not everybody can put up with the weight, or has a face shape that will match a frame.
Polycarbonate is a viable option. It’s much tougher than other plastics, and is lightweight. A pair of polycarbonate lenses fitted into a spring titanium frame weighs about as much as 11 paper clips. It does need to be cleaned much more frequently than glass, and takes longer to get clean.
Plastic is the cheap alternative. It has nothing going for it, apart from price, and invariably misses out on other useful treatments such as anti-reflective coating on the inside and scratch-resistant coatings. No point in putting the best finishes on the cheapest product.
Which colour lens? Lenses can come in any colour, but the two most common hues by far are grey, and then something in the brown/copper/amber sort of spectrum. It used to be that if you were saltwater fishing you got told to buy grey, and for freshwater, choose the other one. But we have progressed.
Grey is neutral, and filters all incoming colours equally. Nothing wrong with that, and I personally probably have more grey-tint sunnies than any other colour. But for fishing, whether it be fresh or salt, you can do better. Amber tint, or something close to it, is a selective filter that knocks out more of the colours high in the spectrum, like blue, and results in more contrast. This is good when you’re trying to discern what’s what underwater. Especially when you don’t have to put up with a lot of glare, your best chance of seeing ‘through’ the water is with a lens colour that exaggerates the contrast between colours. Amber, brown, copper, rose, that kind of thing.
On the other hand, grey lenses are typically darker tints, so better for very bight conditions when you’re not trying to see through water. Maui Jim, for instance, rate their glass lenses at 8 per cent light transmission for grey, at 10 per cent in their rose colour, and their HCL (High Contrast Lens) bronze at 12 per cent. You probably want to think of that more as 50 per cent difference between grey and bronze, rather than 4 per cent. That’s why it’s smart to have more than one pair of sunglasses. In their polycarbonate lenses, those figures are 12, 15 and 16 per cent.
Finally, and I’m skimming over details now, when you buy a good pair of polarised sunglasses, you get more than just a polarising film sandwiched between two layers of lenses. The best of the sunglasses, starting from the eye side, get a nanotechnology waterproof coating, covering an anti-reflective treatment; then a glass lens, polarising film and the other side of the lens, which is topped with a mirror coating (varying degrees), and another waterproof coating. Oils ain’t oils.
If it’s a quality polycarbonate pair, there will be another two layers, being a scratch-resistant coating that goes between the inner polycarbonate and the anti-reflective treatment on the inside, and between the outer polycarbonate and the mirror coating on the outside. That’s nine layers to make a single lens.
Finally, use proper lens cleaners, not anything else. That nanotechnology coating is clever stuff and I could easily write as much again on it alone, but it’s not diamond dust and you can wear it off by cleaning your sunglasses on your shirt. The layer on your lens is about the same thickness as the distance one of your fingernails grew in the last 10 seconds. Buy the good gear, and don’t wreck them.
By Hal Harvey
Copyright © Western Angler 2005-2008
