While binoculars have maintained the same basic structure over the years, modern technology had enabled advancements in the area of lens coating, which has meant better light transmission and thus greater clarity, especially in higher-end binoculars. All binoculars worth considering today should be coated.
Coating the lenses guards against unwanted reflection and transmits as much light as possible to the user. Binocular lenses are typically coated (preferably on all glass surfaces) with a layer of magnesium fluoride. Higher-end lenses may have more advanced antireflection coatings, coating every glass surface with more than one layer.
Look for the words “fully coated,” (or FC) “multi-coated” (or MC) and, for the best of the best, “fully multi-coated” (FMC). (C means, simply, “coated.”) To restate, coated lense binoculars are a necessity. The coating, however, is not intended to protect the glass from scratches, though it is rub-resistant.
Ruby or red coating is a relatively new innovation said to reduce glare, especially in bright light, but some feel it is a gimmick, or a means of trying to compensate for lesser-quality optics. VanGuard, Konus, Vivitar and Meade are among the brands that promote ruby coating on their binoculars’ lenses.
Lens Coating
Lens coatings are chemical coatings on the lenses in a binocular to make images brighter. The coatings on your lenses can have a major effect on the overall viewing experience. A binocular without coated lenses would lose as much as half of its incoming light. The binocular Lenses are coated with chemicals that reduce the light reflected, increasing the light that is allowed to pass through. Each one is a somewhat minor increase, but take altogether the light throughput can be increased by 50% or even more.
Uncoated lenses are wasting a significant portion of the light coming in, and lens coatings simply reclaim that potential. Since this process adds virtually no weight, it does not have a detrimental effect on visibility, and vastly improves the brightness of an image; there is no reason not to go for binoculars with lens coatings.
Types of coating:
Anti-Reflective Coatings: The type and number of coatings applied to binocular or spotting scope lenses make a significant difference in light transmission and how brilliant the views will be.
Coated Lens: This is the lowest level of coating available. This consists of usually one layer of coatings on the front lens element and the eyepiece. When viewed from an angle the lens will have a very faint bluish tint.
Fully Coated: In this type of coating a single layer of magnesium fluoride is applied. This lens coating is only found on inexpensive binoculars and will not produce images as bright as multi-coated binoculars.
Multi Coated: This type of coating allows the maximum amount of light to pass through the lens. A binocular labeled as “multi-coated” will have some, but not all lenses mutli-coated and will be brighter than a “fully coated” binocular.
Fully Multi Coated: This produces the brightest image of any coating system. All quality binoculars will be “fully multi-coated”.
