Must to know!!! TRANSMISSION RATE.

When trying on sunglasses, the customers often ask, "Is there a deeper lens?"

In general, when the lenses are shipped from the factory, some of the lenses are already colored and others is transparent or colorless. After being dyed into sunglasses lenses, when under strong light, why do many people still think that the lenses are not black enough?

One of the important factors is "Transmission Rate" or some people called “Light Transmittance”. Different materials have different transmission rate. Whether it is color or dyed, except for the basic UV400 protection, the light transmittance is The main point you should know.

Fig 1. Different Materials different transmittance

(souce:http://www.oculist.net/downaton502/prof/ebook/duanes/pages/v1/ch051d/002f.html)

 

What is the light transmittance? It can be easily understood literally, the percentage of light that can penetrate through the medium. When the light passes through the transparent or translucent medium, part of the light is reflected by the medium. The other part will penetrate the medium to form a vision. The higher the transmission rate, the better the light transmittance. The reason why sunglasses are needed is that it can weaken the strong light to an acceptable level. As for international or Taiwan standard, the filter is divided into five levels according to the transmittance - CAT.0~CAT.4, and the Polycarbonate (PC) lenses used by Xcube Eyewear are all CAT.3, and the light transmittance is 8%~ 18%, which means that only 8%~18% of the light can penetrate the lens into the eye. All Xcube sunglasses pass the Taiwan standard CN15067 test standard, so consumers can trust on us.

Level

Transmission Rate

Situation

0

80%〜100%

Wind and dust stopped, suitable for night or indoor use

1

43%〜80%

Suitable for dawn and dust use

2

18%〜43%

Suitable for partly cloudy and daylight use

3

8%〜18%

Suitable for daylight and under strong light use

4

3%〜8%

Suitable for special circumstances, like snow. Not recommend use it during driving.

 

It is recommended that when purchasing general-purpose sunglasses, the lens transmittance is best between 15% and 25%, and in special circumstances, such as mountaineering, skiing, cycling, fishing and water sports, etc. It is necessary to choose sunglasses with low light transmittance, and if the structure with full frame coverage and high lens curvature included, the eyes will be effectively protected.

 

Leave a comment