The Leica L-mount 100-400mm f/5-6.3 DG DN OS Contemporary lens, from Sigma, is a versatile telephoto zoom mixing a hand-holdable design with an apt optical performance. A series of low-dispersion glass elements are used to achieve high clarity and color accuracy throughout the zoom range and to suppress chromatic aberrations and color fringing. Complementing the optics is intuitive handling, in which a stepping motor delivers fast, near-silent autofocus performance along with fine-tuned manual focus control.  As part of the Contemporary line within Sigma's Global Vision series, this lens is designed to achieve a balance between convenience and performance and meshes a compact, lightweight build and versatile handling with notable optical attributes. One F Low Dispersion (FLD) element and four Special Low Dispersion (SLD) elements markedly reduce chromatic aberrations and color fringing throughout the zoom range for improved clarity and color accuracy. The integrated stepping motor realizes quick and quiet autofocus, which is further complemented by an optimized AF algorithm to produce a smoother focusing performance. An integrated AFL button can be programmed to adjust various shooting settings and the lens also features a focus limiter switch for faster-focusing performance within certain distance ranges. There is a zoom lock switch to prevent the barrel from accidentally being extended. Compatible with an optional TS-111 Tripod Socket for working atop a tripod or monopod; the included PT-31 Protective Cover can be attached to the lens to maintain a seamless appearance of the tripod socket is not used.