Sigma 18-35mm f/1.8 Overview
The Sony A-mount Sigma 18-35mm f/1.8 DC HSM Art Lens is a wide-angle to normal-length zoom that features a fast, bright constant f/1.8 maximum aperture. It is specifically designed for use with APS-C-sized sensors and provides a 35mm-equivalent focal length range of 27-52.5mm.
The lens integrates four aspherical elements into its construction as well as five Special Low Dispersion (SLD) glass elements to help minimize various aberrations and distortions throughout the zoom range as well as provide greater image sharpness and clarity. A Super Multi-Layer Coating has also been applied to lens elements to reduce surface reflections, lens flare, and ghosting to produce images with higher contrast and color fidelity. The lens barrel design is constructed from a Thermally Stable Composite (TSC) material that is akin to metal in texture and resistance to temperature and environmental changes while also remaining lightweight and compact. An internal focusing and zooming mechanism also helps to maintain a compact and consistent overall length and non-rotating front ring also better enables the use of circular polarizing filters. For control of focus, a Hyper Sonic Motor (HSM) is used to ensure fast, precise, and quiet focusing capabilities that are well suited to continuous shooting and movie recording.