Low Dispersion (LD) Glass for Greater Lens Sharpness

Low dispersion (LD) glass elements in a lens help reduce chromatic aberration; the tendency of light of different colours to come to different points of focus at the image plane. Chromatic aberration reduces the sharpness of an image, but glass with an extremely low dispersion index, has less of a tendency to separate (defract) a ray of light into a rainbow of colours.
This characteristic allows the lens designer to effectively compensate for chromatic aberration at the center of the field (on axis), a particular problem at long focal lengths (the telephoto end of the zoom range), and for lateral chromatic aberration (towards the edges of the field) that often occurs at short focal lengths (the wide-angle end of the zoom range.)

20-40mm F/2.8 Di III VXD (Model A062)

20-40mm F/2.8 Di III VXD (Model A062) Stills. Video. Wide. Fast. Versatile. Category-disrupting ‘standard zoom’ for still photography and video Fast F2.8 standard zoom for Sony full-frame mirrorless cameras covers 20-40mm and offers class-leading1 compact size and light weight Driven by a determined quest for [...]

20-40mm F/2.8 Di III VXD (Model A062)2022-10-12T14:33:08+11:00
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