FLD (“F” Low Dispersion) glass elements FLD glass is the highest level low dispersion glass available with extremely high light transmission. This optical glass has a performance equal to fluorite glass which has a low refractive index and low dispersion compared to current optical glass. It also benefits from high anomalous dispersion. These characteristics give excellent correction for residual chromatic aberration (secondary spectrum) which cannot be corrected by ordinary optical glass and ensures high definition and high contrast images. This lens incorporates two FLD glass elements, which compensate for colour aberration. In addition, two glass mould elements and one hybrid aspherical lens give excellent correction for field curvature and astigmatism. High definition images are ensured throughout the entire zoom range . This lens is in good overall condition with some signs of use. The glass is clean and in good condition. The lens barrel shows some cosmetic marks. There is some light dust within the lens, which would not affect optical performance at all. The focus ring is in good condition. The lens mount shows signs of use.Please note: This lens has a slight amount of moisture within the internal elements, however it does not affect the image rendered.