ED Glass delivers razor sharp images, even at the edges of the field of view. ED stands for "extra-low dispersion" which refers to the composition and optical properties of the glass used for the lenses. ED glass is specially formulated, including rare-earth compounds to greatly reduce chromatic aberration (colors not all coming to the same focal plane), also known as color-fringing, compared to standard crown and flint glasses. By eliminating chromatic aberration, ED glass scopes yield sharper images because the fringes are no longer present to soften the focus providing razor sharp images, even at the edges of the field of view. ED glass is also known for producing images with outstanding, true-to-life color.
Not all ED glass is created equal. Celestron’s high quality ED glass delivers visibly brighter, sharper images compared to non-ED binoculars. The difference is especially apparent in low light conditions, such as at dawn or dusk.