Glass QualityThe optical glass used in a binocular is the only part that directly affects the image quality you see through your binocular. The objective lens of a binocular refracts or “bends” light, attempting to direct that light to a certain focal point at some distance behind the lens of the binocular. Each color or frequency within the visible light spectrum has its own characteristics. As the light passes through the lens, each color bends at a slightly different angle than any other color and, therefore, the various colors focus at different points.
The result is a lack of image sharpness and poor color quality. Certain binoculars incorporate special cost- and labor-intensive glass in the objective lens to correct for chromatic aberration and color fringing. You’ll hear about ED (extra low dispersion) and HD (high definition) glass. When used in binoculars, these glasses provide highly resolved images with enhanced brilliance and exact “true-to-life” color. Even the finest structures will show up well in high contrast and clarity.
Standard grades of optical glass offer good image quality in ideal lighting conditions. For the best performance in low light situations, it is necessary to consider high grades of glass. High-grade glass types, such as ED, FL, and HD, offer noticeably enhanced resolution and color fidelity.
Binocular Glass Types:
ED: Extra-low dispersion glass
FL: Fluoride glass
HD: High-definition glass
