As I was laying on my sofa the other evening watching â€˜Mr and Mrs Smithâ€™ two things struck me. Firstly, I wish I looked like Brad Pitt and secondly, why do movie stars always wear yellow tinted specs when casually firing off a few rounds of a handy AK47? Thankfully, while I know nothing about the grooming habits of Mr Pitt, I do know a little about tints and lens colours. So here is a brief summary to ponder over the next time you canâ€™t decide how to look the part with a cool M16 gadget…

Tints tend to fall into two categories; cosmetic or functional. The choice of colour can range enormously depending on use, preference or even your hair colour! Regardless of colour though, they have to be 100% UV protective and it is important to note that both very pale and a very dark tints can provide this. Cosmetic tints are normally bright colours and are more of a statement so look out for pinks, blues and reds. Functional tints tend to be brown, grey or yellow (as worn by Pitt).

The key reason why some colours are recommended for particular tasks over others is down to the wave-length of light they block out. For example, a brown tint (as it contains yellow) is much better at blocking out the middle of the visible spectrum, creating a much better contrast between the low end and high end of the spectrum. This is perfect for driving, skiing or sport. A grey tint on the other hand blocks out the spectrum evenly. While this doesnâ€™t provide a better contrast, it helps to reduce intense light and glare from the sunâ€™s rays. Yellow is much better for definition as it highlights objects better, allowing for faster reaction times. This is because yellow is the only colour that falls exactly on the retina and is therefore the colour that the eye is most sensitive to. This is why police cars have yellow stripes.

So next time youâ€™re off on a mission or just off down the pub, choose wisely…you never know what you may need to see.