With so many on offer right now, it is good to have a make you can trust. The Sigma 8-16mm f4.5-5.6 DC Lens for Pentax Digital SLR Cameras with APS-C Sensors is certainly that and will be a superb acquisition. For this great price, the Sigma 8-16mm f4.5-5.6 DC Lens for Pentax Digital SLR Cameras with APS-C Sensors comes widely respected and is a regular choice with lots of people.
The first ultra wide zoom lens with a minimum focal length of 8mm, designed especially for APS-C size image sensors. The wide-angle of view and exaggerated perspective enables the photographer to emphasise the subject. Four FLD ("F" Low Dispersion) glass elements, which have the performance equal to fluorite glass, compensate for colour aberrations. Two glass mold elements and one hybrid aspherical lens give excellent correction for distortion and astigmatism. Incorporating an internal 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. The Super Multi-Layer Coating reduces flare and ghosting. It provides sharp and high contrast images throughout the entire zoom range. This lens incorporates HSM (Hyper Sonic Motor), ensuring quiet and high speed AF as well as full-time manual focus capability. The lens has a compact construction with a diameter of 75mm, overall length of 105.7mm and weight of 555g. This compact and lightweight construction makes it ideal for travel photography. This lens has a minimum focusing distance of 24cm throughout the entire zoom range and a maximum magnification ratio of 1:7.8.