Q My friend says I should insist on a "multi-coated" riflescope. What does this mean?
A Those who know how important lens coating is to riflescope performance are often interested to know how coating works. When light enters and exits glass, a lens for instance, about 4% is reflected away at each surface. By coating the lens surfaces with one of several suitable metallic oxides and fluorides to a critical microscopic thickness the reflections can be reduced considerably. This process, termed destructive interference, works by phase shifting the reflected light rays (putting them out of step with the incoming light rays) thereby killing the reflections by converting them to another form of energy.
A typical riflescope has about twelve lens surfaces which, if
uncoated or partially coated, would produce a degraded low-contrast image due
to inter-lens reflections. Coating could be expected to improve total transmission
from 60% plus to 80% plus of the light entering the system. Multi-coating is
a further refinement, involving the use of several coating materials which are
applied selectively to lens elements in a riflescope or binocular to optimise
light transmission to about 90% and balance image colour - and for specialised
equipment to shift image colour to suit the human eye’s greatest sensitivity
region. The effect of high grade multi-coated optics is seen in the crystal
clear colour true images of Lynx Professional and Twilight series riflescopes.
They give the hunter every advantage in good light and in poor light and when
aiming towards the rising or setting sun.