Lenses
FOR GOGGLES & SUNGLASSES
Written on 10 July 2013 by Susan Dun
When you’re up on the mountain your eyes are constantly exposed to the effects of the sun – which is stronger at altitude and magnified by bright snow.
UV can be very dangerous to unprotected eyes, causing temporary or even permanent eye damage while strong sunlight combined with snow can make it hard to see and cause eye strain or headaches.
In bad weather or low light it can be very hard to see where you’re going or make out the contours of the slopes making you feel like a beginner again on a white out day.
Good sunglasses or goggles protect your eyes from UV and glare and help you make the most of the available light whatever the conditions so you can make the most of your time on the slopes.
The key feature for both protection and good vision is the lens, and there's a lot of science and technology to it.
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Lens Colours
Different colours of lenses alter your perception of light and colours in different ways, so some lenses are suitable for very bright weather, some are best in low light conditions and some are reasonably versatile.
Using the wrong colour of lens for the conditions can make seeing where you’re going and what you’re doing a lot more difficult than it needs to be and choosing the right lens colour can make a massive difference.
Grey Lenses
Grey Lenses give a very natural perception of light and colours so they’re great for cutting the glare in bright sunshine (ideal for sunglasses).
But they don’t help increase contrast at all in bad light so grey is not a good choice for goggles for bad weather.
Many bargain basement goggles have a grey lens which is one good reason not to buy them!
Brown Lenses
Brown Lenses are a bit more versatile than grey - colours are slightly less natural than with a grey lens but it’s not too noticeable, and contrast and depth perception is a bit better than grey. Still mainly for sunglasses and bright weather though.
Orange / Amber Lenses
Orange / Amber Lenses – distort colour perception more than a neutral grey or brown lens, so orange/amber isn’t as good in bright sunshine and not as common in sunglasses.
Contrast is increased so orange/amber is a good colour for a reasonably versatile goggle lens.
Pink Lenses
Pink Lenses give slightly more accurate colour perception than orange so a bit better in brighter light.
Pink lenses also increase definition and contrast in flat light so are good for reasonably versatile goggles.
Yellow Lenses
Yellow Lenses work very well in low light so they’re great for goggles specifically for bad weather but they give a very distorted vision of colours so they’re not good at all for brighter light.
Blue Lenses
Blue Lenses are less common but have an amazing brightening effect in very bad conditions – but as soon as it gets brighter, they’re too bright and quickly tire the eyes.
Choosing the right lens colour – unless you have several pairs of goggles or sunglasses – will always be a bit of a compromise. There’s no lens that will be perfect for all conditions.
Orange/amber or pink are the most versatile for the widest range of conditions, but will never be as good in the extremes of bright sunshine or flat light as lenses specifically designed for those conditions.
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Lens Categories
How dark the lens is – regardless of its colour – is defined by the lens category – 0 to 5. The denser the colour, the darker the lens, the less light it lets through, the more it’s suitable for brighter weather.
So as well as the lens colour, the colour density is another factor you need to take into account when choosing your goggles or sunglasses.
Category 0 – very light, only for fashion use, not for snowsports.
Category 1 - still very light, mostly for low light goggles, not suitable for bright weather at all.
Category 2 – medium density, good for reasonably all-round goggles, still not dark enough for bright sunshine and snow.
Category 3 – a fairly dark tint, the most common category for snowsports sunglasses and good for goggles in bright weather.
Category 4 – very dark, great for bright sunshine at high altitude and for people with sensitive eyes. Quite rare in goggles and not suitable for driving because they’re so dark.
WARNING ! The lens category has nothing to do with the amount of UV protection the lens provides. In any decent pair of goggles or sunglasses, even a totally clear lens should provide 100% protection against UV – look for the UV400 logo.
Mirrored Lenses
Mirrored lenses aren’t just for the look, and these days not all mirrored lenses are for bright sunshine either. What a mirror lens is suitable for depends on a combination of the base lens colour, its colour density and the kind of mirror coating used.
Uniform mirror lenses are the cheapest and simplest kind, they reduce further the amount of light getting to the eye and are for very bright weather.
Flash mirrors give a more subtle look and cut less visible light than a uniform mirror. These make a base lens which would on its own be best for medium to low light a bit more versatile in brighter weather and give a good all-round option.
Multilayer or dielectric mirrors are most often at the top of the range, they’re bright and funky but have practical features too. They use layers of different electrically-charged materials to change or enhance the characteristics of the base lens.
A multilayer mirror can make a base lens which you’d expect to be better in bright sunshine give more definition and contrast in low light. Or it can be used to improve colour perception in a lens which would generally be suitable for lower light conditions, making it better for bright weather. They’re all different so you need to read the label or box, or ask for advice.
WARNING ! A mirrored lens does not increase the amount of UV protection the lens provides. In any decent pair of goggles or sunglasses, even a totally clear lens should provide 100% protection against UV – look for the UV400 logo.
Polarised Lenses
Rays of sunshine normally reflect mainly vertically, but when they come into contact with a flat, reflective surface they can become polarised and reflect horizontally too, amplifying the brightness and glare, making vision difficult and causing eye strain and headaches.
Polarised lenses contain a filter which eliminates the horizontal glare and they’re great for things like watersports and fishing as they cut the glare reflected from the flat surface of the water. They’re good for driving too.
It has to be said that some people don’t think a polarised lens makes a lot of difference for skiing as there aren’t a lot of flat surfaces around to reflect glare. .
Some people positively don’t like them as they say it makes it harder to see icy patches. But others do find a polarised lens a big advantage as the reduced glare means better definition. However you feel, one thing’s sure, if you want sunglasses you can use for watersports as well as skiing, polarised lenses are a good choice.
WARNING ! A polarised lens does not increase the amount of UV protection the lens provides. In any decent pair of goggles or sunglasses, even a totally clear lens should provide 100% protection against UV – look for the UV400 logo.
Other Lens Types and Treatments
Other lens features to look for include photochromatic lenses, which darken or lighten depending on how bright it is and can make the same goggles or sunglasses suitable for a wider range of light conditions, and anti-scratch, anti-reflection and anti-fog treatments or coatings.
And some models offer interchangeable lenses which either come with the goggles or sunglasses or can be bought separately, making the same frame more versatile.
Lens Quality
Cheap sunglasses or goggles or those designed for fashion use often have poor quality lenses which can distort your vision, make you squint and cause eye strain or headaches. This is especially common with modern curved or spherical lens shapes which are both fashionable and provide the best coverage, protection and peripheral vision.
With good quality lenses, the lens material is engineered to maintain optical quality and undistorted vision right across the lens. Cheaper versions may look just as good superficially but lens curvature may lead to significant visual distortion towards the edges.
Goggles or sunglasses for skiing or snowboarding should always have optical quality Class 1 lenses, which are the same quality as prescription lenses.
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