ED glass stands for "Extra-low Dispersion" glass, which is a type of optical glass used in binoculars to reduce chromatic aberration. Chromatic aberration is a common problem in optical systems that causes different colors of light to be refracted or bent at slightly different angles, resulting in blurry or distorted images.
ED glass is made by adding rare earth elements such as lanthanum or fluorite to the optical glass during the manufacturing process. This helps to reduce chromatic aberration and produce clearer, sharper images with more accurate colors.
Binoculars with ED glass typically have a higher price point than those without, but they can be well worth the investment for birders, nature enthusiasts, and anyone else who wants to enjoy crisp, clear images without the distraction of chromatic aberration.
It's worth noting that not all binoculars labeled as "ED" actually contain genuine ED glass. Some manufacturers use other techniques, such as multiple lens elements, to reduce chromatic aberration without using ED glass. Some also use a small amount of ED glass (in the eye lens for example) so they can put ED on the marketing material and packaging!
As a result, it's important to do your research and read reviews before purchasing a pair of binoculars with ED glass. All Focalpoint staff are aware of these ploys by manufacturers and they will be able to guide you to the best optics for your needs.