![]() ![]() These are the most damaging frequencies of light which are the biggest threat to your skin and eyes.īecause of this, UV needs a different type of filtration to visible light in order to prevent you from permanently damaging your eyes.Įven if a sun lens is really dark, this doesn’t improve it's UV protection. UV ranges from 10 to 400 nano metres which is sectioned into UVA, UVB and UVC. But UV inhabits an invisible range of frequency which is why we can’t see it. Sure, they’re both on the electromagnetic spectrum. This is because visible light is not the same as ultraviolet light (UV.) To control the VLT of a lens, a darkening tint must be applied in form of a coating or a film.įor sunglasses, tint coatings are applied by dipping the lens in a coloured liquid solution inside a heated tint-bath.ĭespite this dark coating, the reduction of visible light transmission does not protect you from ultraviolet light. which a fantastic way to block reflected glare. This puts them on the darker end of category 3 which makes them perfect for most daily tasks on bright sunny days. This way, you can keep yourself on the right side of the law (and the road.)Īt Banton Frameworks, our lenses are a category 3 with 14% VLT. So, unless your planning to watch the next solar eclipse, it’s worth checking the VLT% of your next pair of sunglasses if they seem a little too dark. If you want a dark lens, be sure to stick to a category 3 at the very most.Ĭategory 4 sun lenses are generally used in extreme-exposure situations.įor example, Mountaineering sunglasses can be fitted with 5% VLT lenses and side-shields to minimise the risk of snow blindness. They can diminish the light from traffic lights and indication from other cars. They’re simply too dark for you to operate a vehicle safely. Oh and category 4 sun lenses? They’re illegal for driving your car in the UK. On the flipside, lenses with 8% VLT or less can seem overly dark and begin to impede your vision, especially if it’s not a particularly sunny day. Just be sure to ask first before you walk outside the shop with them, right? Some fashion sunglasses may have a lighter tint on their lenses, so it’s worth seeing how they perform outside before committing to buying them. Most, if not all general-use sunglasses are fitted with a category 2 or 3 lens. You may end up squinting or frowning to compensate which can lead to headaches over a long duration. In basic terms, it’s really your personal preference over how comfortable your eyes will be in certain light conditions.įor daily tasks like driving or taking a stroll in the sun, a category 2 or 3 sun lens will generally work well for you.Īny lighter than a 43% VLT and you’ll probably struggle on those really bright days. Seen in the table above, VLT% can influence how and when you want to use your sunglasses. These categories have varying suitability’s for varying applications. For you, this determines your visual comfort on bright sunny days.īased on the VLT%, the darkness of a sunglasses lens is categorised into 4 types. ![]() High VLT% lenses will transmit more light and will be light to look through.īut how does that affect your purchase decision when it comes to buying new sunglasses? Low VLT% lenses will transmit less light and will be dark to look through. Using a device called a photometer, this measures the intensity of visible light before and after it passes through a lens. In the context of Visible light transmission, this action is measured as a percentage ranging from 1% to 99%. The lower the VLT, the darker the sun lens will be.īut let’s look into how VLT% can influence your purchase decision, the comfort of your eyes and how it categorises your sunglasses into one of four types.Īs visible light meets a lens it can either be reflected, absorbed or transmitted. This is measured as a percentage which indicates the darkness of a lens within a sunglasses frame. It can also be called visible light transmittance or VLT%. Visible light transmission is the amount of visible light that can pass through an optical or sun lens. So, I’ve done a little research to clear things up. Looking for a new pair of shades, it’d be good to understand what this phrase means. ![]() Yep, sunglasses are good at protecting your eyes.īut what’s this term “visible light transmission” all about? ![]()
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