History

    APO

    These lenses include one or more elements made of ELD (Extraordinary Low Dispersion), FLD (“F” Low Dispersion), or SLD (Special Low Dispersion) glass, which help minimize chromatic aberration, which can harm image quality. In wide-angle lenses, they help correct mainly axial chromatic aberration, while in telephoto lenses, they help correct mainly transverse chromatic aberration.