Lens Technology: LD (Low Dispersion) lens elements

The characteristic of less of a tendency to separate a ray of light into a rainbow of colours effectively compensates for chromatic and lateral chromatic aberration

LD lens elements in help reduce chromatic aberrations. Chromatic aberration reduces the sharpness of an image, but glass with an extremely low dispersion index has less of a tendency to separate (diffract) a ray of light into a rainbow of colours. This characteristic allows the lens designer to effectively compensate for chromatic and lateral chromatic aberration which are a particular problem at wide-angle and telephoto focal lengths.