What is an anti-reflective (AR) coating on the lens?
The purpose of a lens is to transmit as much light as possible. As the light passes though an untreated air/lens surface, 4% of the available light is reflected back. This reflected light is wasted. A glass lens has two air/lens surfaces – one on each side of the lens and thus 8% of the light can be lost. An anti-reflective coating can be applied to the lens surfaces to reduce the amount of reflected light and thus increase the amount of light transmitted through the lens. Both surfaces should be coated to maximize the amount of light the lens can transmit. An anti-reflective coating is a vapor deposition coating that is applied in a vacuum. The coating is a fraction of a wavelength of light thick and acts like a tuned circuit in electronics to match the “impedance” between the lens and the air. This allows the lens to capture and transmit the light that would otherwise be reflected. The anti-reflective coating is fairly durable but it is very thin. Excessive rubbing will abrade the co
