What are lens coatings?
A19. Lens coatings are chemical coatings on the lenses in a binocular that make images brighter. Binoculars can have up to 16 air-to-glass surfaces. When light strikes each surface, some of the light is transmitted, and some of the light will be reflected. In an image forming optical instrument such as a binocular, ideally no light should be reflected. Instead of forming an image, light which reaches the viewer after reflection is distributed in the field of view, reducing the contrast between the true image and the background. Reflection can be reduced, but not eliminated. A binocular without coated lenses could lose as much as half of its incoming light.
How many times have you looked through a pair of binoculars and been blinded by a “chain of light” effect? This is because the lenses and prisms either have inferior, or lack completely and kind of chemical coating. These coatings vastly decrease both the amount of light lost due to external reflection and the unnerving internal reflection caused by inferior coatings. Without quality chemical coatings on your optics, even good quality lenses will suffer a great loss of clarity and, through internal reflection, produce a dizzying amount of reflection.
Coatings are applied to the glass elements to reduce the amount of light with is lost due to reflections. Generally binoculars and spotting scopes are coated with a single layer of coating applied to each glass surface. More expensive models have multi-coatings applied with further reduces the amount of light lost to reflections.
