Spotting Scope : Glass quality and coatings
Glass quality and coatings explained
1 Extra-low dispersion (ED) lenses ED lenses are the most effective way to improve image quality and stop colour fringing (chromatic aberration). ED glass allows for better concentration and direction of light wavelengths, which give a significantly sharper image and improved contrast of colours and light.
2 Fully multi-coated (FMC) lens coating There are many lenses within an optical system. Hawke’s FMC lenses ensure that both sides of every lens have multiple layers of coating which assist with light transmission and help produce brighter images with improved contrast.
3 BAK-4 porro prism A prism is a system of glass elements inside the spotting scope that ensure the viewed image is the correct orientation after being magnified. BAK-4 glass ensures excellent light refraction properties and is superior to BK-7 glass.
4 Dielectric coating Dielectric Coating of the prisms improves internal reflection even more than a silver mirror coating. This maximises the quality of visible light and produces clear, high-contrast images, similar to those seen by the naked eye. Further spotting scope terminology.