Snow conditions are constantly changing on the mountain, and just like the differing snow conditions, you can also experience a multitude of light conditions such as sunny, partly cloudy or even night skiing. The days of only having one lens for your goggles to deal with all light conditions are over. Every goggle brand offers many different lens options. Just like you wouldn’t use a ski with a 76mm waist to ski powder you wouldn’t want to use a lens with a low VLT rating to ski in overcast conditions or for night skiing. I know we all want to look cool with our mirrored lenses, but if you wear a really dark lens in low light conditions you’re going to have a bad time, just like if you French fry when you are supposed to pizza.
So now you‘re probably asking what is VLT rating? Well VLT stands for Visual Light Transmission, and what this refers to is how much light is allowed to enter the lens. The VLT rating is shown as a percentage. This percentage will tell you how much light enters the lens, so a lens with a VLT rating of 60% will allow 60% of the light through the lens. You can really narrow down light conditions into one of 4 categories: low light, overcast, partly sunny, or full sun.
A lens with a high VLT rating is best used in low light conditions, like night skiing or days where it’s dumping snow on you. Lenses with a VLT rating of over 60% will allow the most light to enter, allowing you to pick up the varying snow conditions on the mountain. A good example of lens with a high VLT rating is the High Intensity Yellow lens from Oakley. The next category is overcast, also referred to as flat light, meaning the sun is completely covered by clouds providing no shadows and it makes it hard to pick up the lines in the snow. These lenses are slightly darker than low light lenses but they are still made to allow most of the light through the lens, they will have a VLT rating between 50% and 60%. These are lenses like the Red Sensor Mirror from Smith or the Persimmon Boost from Giro. The partly sunny category is for days where you are getting peeks at the sun, but there are still clouds in the sky, and it’s a little darker out than on full sun days. This is also where you will start to get lenses with a mirrored finish. These lenses will have a VLT rating below 50% but above 30%. Some examples of this category are the Red Solex lens from Anon or the Metal Mirror lens from Zeal. The last category is the full sun, blue bird days are the best aren’t they? These are the days where there is not a cloud in the sky; it’s just you and the sun. These lenses will allow the least amount of light to enter the lens and will have a VLT rating lower than 30%, but they will still protect your eyes from harmful rays. Best examples here are the Fire iridium lens from Oakley or Green Sol-X from Smith.
If you don’t want to have multiple lenses that you need to change depending on conditions, you can get a photochromic lens. Photochromic lenses offer you great visibility in varying light conditions because they adjust with the exposure of UV radiation coming from the sun. The more sunlight, the darker the lens becomes; the less sunlight, the lighter the lens becomes. The one drawback of photochromic lenses are they generally take a little longer to adjust in colder conditions.
The overall concept when talking about light transmission is the higher the percentage the more light goes through the lens, the lower the percentage the less light is able to enter through the lens. So just like how you’re building your quiver of skis, it is time to start building a quiver of goggle lenses to help deal with all the light conditions you experience on the mountain.