Introduction.
[b]Lens[/b]Binocular anti-reflective lens coatings are often the least understood, yet are one of the most leading features relative to the quality of the binoculars. Lens coatings conclude how well you are going to see your image, the clarity of color, the resolution, and the contrast.
Background.
Realize that there are a series of internal glass surfaces within binoculars. As light enters straight through the front objective lens it travels straight through the binoculars. As it hits each series of uncoated glass surfaces practically 5 percent is reflected (lost). Assuming ten internal sets of glass surfaces, times 5 percent reflective loss at each, equals a total of a 50 percent light loss as the image reaches the rear ocular lens. The effect will be a dim, hazy, unclear image.
Anti-reflective lens coatings allow a greater percent of the light to pass straight through each series of glass surfaces. Instead of the 5 percent loss, coated lens may reduce that form to less than 1 percent. A smaller division of the light is reflected and a greater number continues on to the ocular lens. In better, high quality binoculars in excess of 95 percent of the light reaches the ocular lens and your eyes. This results in a sharp, clearly defined, and spicy image.
Types of Lens Coatings.
Binocular anti-reflective lens coatings are rated in one of four categories.
1. Coated Lens. (C) Contains a single coating on at least one set of the internal series of glass surfaces. The first and last set of lens are probably coated, but the remaining sets probably are not:
Example: ____ || ____ | ____ | ____ | ____ | ____ ||
Note: Typically, coated lens have only the first and last lens of the binoculars coated. The first and last lens are the ones you can see (the front objective lens and the rear ocular lens).
2. Fully-Coated Lens. (Mc) Contains a single coating on all sets of the internal series of glass surfaces. Each set of lens receive a single coating:
Example: ____ || ____ || ____ || ____ || ____ || ____ ||
3. Multi-Coated Lens. (Fc) Contains manifold coatings on at least one set of the internal series of glass surfaces. Often the first and last lens are multi-coated, while the remaining lens may be single coated:
Example: ____ |||| ____ || ____ || ____ || ____ || ____ ||||
4. Fully Multi-Coated Lens. (Fmc) Contains manifold coatings on all sets of the internal series of glass surfaces. Each series of lens are fully multi-coated:
Example: ____ |||| ____ |||| ____ |||| ____ |||| ____ |||| ____ ||||
As we have shown with our four categories, the Fully Multi-Coated models are vastly excellent when compared to the other three categories.
The Coating Process.
Lens coating is a process where clear chemicals (such as metallic, silver, or aluminum) are physically applied to the glass lens of the binoculars to allow light to pass straight through and not be reflected. Generally, one coating may reduce light reflection from the 5 percent for untreated glass to 1 percent for a coated lens. Multi-coating commonly uses magnesium fluoride or calcium fluoride to further reduce reflection. Each glass is typically coated 3 to 5 times (and at times upwards of 10 times) to generate a situation where near 100 percent of the light reaches your eyes.
A end Recap.
Listen intimately to the salesperson, or understand what you are reading, when a reference is made to lens coatings. The type of lens coatings go a long way to determining the quality of the image you will be seeing.
o Fully Multi-Coated Lens produces the very best quality images.
o Multi-Coated Lens is a step below the best, but still furnish quality images.
o Fully Coated Lens furnish good images that are standard to most users.
o Coated Lens is normally found in the most uncostly binoculars.
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