The Sigma 8-16mm f/4.5-5.6 DC HSM Lens For Pentax Mount  is the first ultra wide zoom lens with a minimum focal length of 8mm, designed especially for APS-C size image sensors. Four FLD glass elements and three aspherical lenses provide high image quality.
This is the first ultra wide zoom lens with a minimum focal length of 8mm, designed especially for APS-C size image sensors. The wide-angle view and exaggerated perspective enables the photographer to emphasize the subject. The incorporation of HSM ensures quiet and high speed AF as well as full-time manual focus capability.
The wide-angle of view from 121.2 degrees
Sigma, the pioneers of wide angle zoom lenses, launched the first wide angle zoom lens, the Zoom Gamma 21-35mm F3.5-4, in 1979. After that, we have continued to develop and apply wide angle zoom lenses with cutting edge technology. The 8-16mm F4.5-5.6 DC HSM is the first ultra wide zoom lens with a minimum focal length of 8mm, designed especially for APS-C size image sensors. This lens has an equivalent angle of view of a 12-24mm lens with a 35mm SLR Camera.
The wide-angle of view produces striking images with exaggerated perspective, enabling photographers to emphasize the subject.
Superior image quality
Four FLD ("F" Low Dispersion) glass elements*, which have the performance equal to fluorite glass, compensate for color aberration. Two glass mold elements and one hybrid aspherical lens give excellent correction for distortion and astigmatism. Incorporating an inner focusing system, the lens produces high definition images throughout the entire zoom range.
*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.
Super Multi-Layer Coating
The Super Multi-Layer Coating reduces flare and ghosting. It provides sharp and high contrast images throughout the entire zoom range.
Quiet and fast AF
This lens incorporates HSM (Hyper Sonic Motor), ensuring quiet and high speed AF as well as full-time manual focus capability.
*For Pentax mount, AF will not function with DSLR cameras that do not support HSM.
The lens has a compact construction with a diameter of 75mm, overall length of 105.7mm (4.2") and weight of 555g (19.6oz.). This compact and lightweight construction makes it ideal for travel photography.
Minimum focusing distance of 24cm (9.4")
This lens has a minimum focusing distance of 24cm (9.4") throughout the entire zoom range and a maximum magnification ratio of 1:7.8.
*Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras. * AF will not function with Pentax ist* series and K100D DSLR cameras that do not support HSM. * Filters cannot be attached to this lens.