There are many lenses within a binoculars 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.
– BAK-4 is a type of glass used within the prism, which is a system of glass elements inside the binocular that ensure the viewed image is the correct orientation after being magnified. A roof prism is a more compact and sharper version of older traditional Porro prisms.
The light traveling through a binocular prism is reflected several times and as such can lose its “phase”, meaning that colours can appear overlapping and produce colour fringing, also known as chromatic aberration. A phase correction coating helps to stop chromatic aberration.
A silver mirror coating can be applied to elements within the prism and increase reflection. This also improves brightness and colour reproduction. The silver coatings have a reflectivity of 95% to 98%.
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.
Water repellent coatings significantly improve optical performance in wet weather conditions. The extra lens coating encourages the water droplets to “bead” and form into smaller drops that are easier to clean and will more actively run off the glass lens.
Extra-low dispersion (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.