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Tinted Lens 69

Those who can not tolerate colour distortion or whose job requires accurate
colour discrimination, also favor grey tint. Grey lenses offer good protection
against glare, making them a good choice for driving and general use.
Because it absorbs light equally over the whole visible spectrum, it is not
the best contrast enhancing colour.

Yellow: Chromium or sulphur oxides are used to give rise to yellow tint
filter. Uranium oxides can also be used for the same purpose. Yellow filters
absorb blue, violet and UV light while allowing a larger percentage of other
frequencies through. Since blue light tends to bounce and scatter, it can
create a kind of glare known as blue haze, thereby reducing the contrast.
The yellow tint virtually eliminates the blue/UV end of the spectrum and
has the effect of making everything bright and sharp. The tint concentrates
light in the area of the spectrum to which the eye is most sensitive. If an
individual is already light sensitive then the experience is heightened
looking through a yellow or orange filter. Someone who is not light sensitive
would really appreciate the contrast enhancing effect of yellow filter. That
is why yellow filter is likely to be favored in visually demanding sports
like trap shooting and snow skiing, especially on overcast days. This tint
really distorts colour perception, which makes it inappropriate for any
activity that relies on accurate colour.
Blue: Small concentration of cobalt (0.025% to 0.1%) yield blue glass. Blue
filter glass is likely to transmit more dangerous high energy part of the
spectrum, i.e. shorter wavelengths blue and UV while absorbing the light
into the yellow and orange wavelengths. The eyes lack of sensitivity to this
part of the spectrum adds to the danger. But the absorption in the yellow
wavelength makes it good for light sensitive individuals. But the light
scattering effect of the blue light out weighs the relief they get from the
elimination of peak sensitivity wavelength of yellow and orange. Because
of the danger of high energy blue light intensified by the brilliance of the
sun, blue tint is not advisable for outdoor use. It can be prescribed for boiler
tender, smelters, foundry work and certain types of furnace work. As it is
not good UV and IR filter, it is not intended for welding application.
Green: The green tinted glass lens obtains its colour and characteristic
transmission curve from ferrous oxide metal. Green filters transmit
wavelengths of around 500 nm, i.e., green as well as yellow, orange and at
the higher end red while absorbing some, but not all of the blue – violet
region. It has a good UV as well as infrared heat absorbing properties. It
makes a very good sunglass tint because of its contrast enhancing properties.
It allows true colour perception and real protection in bright light. It reduces
eyestrain in bright light and also glare. It is a good intermediate filter to
use when grey or yellow does not seem right.