The ins and outs of sunglass selection
Fashion and image play a large role in sunglass selection and the advertising onslaught in TV and films that portray the celebrities in ‘cool’ sunshades have continued to increase their popularity as a fashion icon. Styles can range from conservative to outrageous, and come in every conceivable colour. There is a certain mystique when someone wears sunglasses. It is often said that the eyes are the windows to the soul, so it is no wonder that a device that hides them makes the wearer seem more provocative and mysterious says Designer Fashion.
The Sunglass lens Lenses come in various shades and a ranges of colours. They are also made in solid tints and in gradient tints, where the top of the lens is darker than the bottom. However, the two most important aspects to bear in mind are the transmittance properties and optical properties
Colour Tinting The colour of the tint determines the parts of the light spectrum that are absorbed by the lenses. Manufacturers use different colours to produce specific results. Gray tints are great all-purpose tints that reduce the overall amount of brightness with the least amount of colour distortion. Gray lenses offer good protection against glare, making them a good choice for driving and general use. Yellow or Orange tints reduce the amount of blue light while allowing a larger percentage of other frequencies through. Since blue light tends to bounce and scatter off a lot of things, it can create a kind of glare known as blue haze. The yellow tint virtually eliminates the blue part of the spectrum and has the effect of making everything bright and sharp, that’s why snow glasses are usually yellow or orange colour. This tint really distorts colour perception, which makes it inappropriate for any activity that relies on accurate colour. Amber and brownish tints are also good general purpose tints. They have the added benefit of reducing glare and have molecules that absorb higher frequency colours, such as blue, in addition to UV rays. There has been research that suggests that near-UV light frequencies such as blue and violet can contribute to the formation of cataracts over time. These tints also distort colours similar to yellow lenses, but increase contrast and clarity. Green tints filter some blue light and reduce glare but because green tints offer the highest contrast, clarity and greatest visual acuity of all the tints, they are the most popular. Purple and rose tints offer the best contrast of objects against a green or blue background. They make a good choice for hunting or water skiing. Dark Rose/red tints are good sports lenses that increase visual efficiency and the degree of image definition in poor visibility, and flat light conditions. They cut back the reaction time in situations improving both sports performance and safety such as Golf Sunglasses.
Gradient Colour Tinting A coloured coating is applied as a gradient that gradually changes shades from top to bottom. This provides additional protection from light coming from above while allowing more light to come in from below or straight ahead. The Gradient lens is THE preferred choice of military and commercial aviators. The top gradient acts to block the sun’s glare at the top of the lens, while providing a clear view of the dashboard and instruments at the bottom. Gradient lenses allow easy reading of charts and instruments inside an aircraft or a car while protecting your eyes from UV rays outside. Aircraft pilots choose thin light frames to house these lenses because frames with thin, strong arms are comfortable while wearing headsets. Police officers who work outside use these Sunglasses because they are very durable and resist scratching while providing the best possible protection from UV rays - a must for pilots and drivers alike!
Transmittance properties. The “luminous transmittance” value denotes the amount of light that the lens lets pass through. The higher its value, the more light the lens absorbs and the less light it lets pass through. The other main objective is to make sure that our lenses have good optical quality and give accurate, sharp vision without distortion.
We also ensure tha the lenses give protection against UV radiation, good clarity of vision and colour fidelity and are suitable for driving. Some sports glasses are not suitable for driving because they distort colour -.Lenses that distort colours for long periods of time can cause headaches, eyestrain and fatigue. As well as being uncomfortable, the inability to distinguish colours can be dangerous- for example if you were unable to recognise the colour red at traffic signals! For simplicity many manufacturers use a numbering system to denote the darkness of the lens using a scale of 1 to 3. This helps you choose sunglasses by providing a system of filter categories that describe the darkness of the tint (luminous transmittance) such as Smith Sunglasses.
There are 3 filter categories
1 Light Tint from 43% to 80% luminous transmittance. 2 Medium Tint from 18% to 43% luminous transmittance. 3 Dark Tint from 8% to 18% luminous transmittance.
However other lenses such as Polarised lenses, Photo Chromatic lenses and Gradient tinted lenses don’t always adhere strictly to these guides. In summary:
Filter No 1 has little shade and used mainly to make a fashion statement. Filter No 2 is in between very light and dark and used mainly for outdoors. Filter No 3 is dark and used when lots of time is spent in the Sun. (Note: some American brands of sunglasses use different numbers for filtering e.g. Rayban’s aviation glasses are G15 which means green with 15% transmittance that is equivalent to our No 3)
The rest is down to styling, finishing, detail and personal preference
Mirror Coating can be added to the outside of your sunglass lenses to give that “cool” look!
Reflective sunglasses sometimes have a mirrored look. We call these “reflective lenses” and they have a reflective coating applied in a very thin, sparse layer — so thin that it’s called a half-silvered surface.
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