meniscus glass

Nikon s exclusive protective glass for NIKKOR lenses comes attached to the front of fast super-telephoto lenses. Normal flat protective glass lets incoming light reflect off the surface of the image sensor or film, especially under a strong light source such as a spotlight. This then reflects again off the protective glass, resulting in a ghost effect. Nikon s curved meniscus glass dramatically reduces this re-reflected light, realizing clearer images with less ghosting.