Oberwerk Broadband Multi-Coatings
All Oberwerk binoculars are FBBMC (Fully Broadband Multi-Coated). Multi-coatings are used to minimize reflections, the purpose is to transmit as much of the light entering the binocular’s objectives as possible through every lens surface until it exits the eyepiece on the way to your retinas, with as little loss as possible from reflections and scattering. “Fully” means that every air-to glass surface is multi-coated. “Broadband” means that the multi-coating is as efficient as possible across the entire range of the visible light spectrum (400-700nm).
In reality, multi-coatings don’t have the same reflectivity throughout the range of visible wavelengths, but the technology is continually improving. The A4 type is currently the most popular multi-coating found on today’s high-quality binoculars. All Oberwerk models have either A4 multi-coatings or the newer A5 type (some of the Ultra Series).
But we’re constantly innovating, and are currently working on an even more-efficient type A6! We believe A6 will be exclusive to Oberwerk, at least until the other brands eventually catch up. Note that coating type can affect the hue of the coating. That hue does not affect the view in any way, in other words, that hue is not acting as a color filter- it’s just showing which wavelengths of the visible spectrum are a little more reflective. Notice that the A4 coating is less efficient at the bottom end of the visible range, resulting in some purple reflection, and has a rise in reflectivity in the 500-550nm range, which adds a greenish hue. A5 coatings have a small rise in reflectivity around 450nm (purple-blue) with a gradual rise at starting at 600nm toward the red end of the spectrum, resulting in purple/orange/reddish hues. Note that the human eye is less sensitive to red, so a little more reflectivity in that range has less impact on efficiency.
