Sigma 210101 18-35mm F1.8 DC HSM Lens for Canon APS-C DSLRs (Black) + 12 Piece Deluxe Accessory Package Kit Art Lens Line This lens is part of Sigma's Art line; deeming it well-suited to creative image making due to its large, constant f/1.8 maximum aperture and ability to produce aesthetic bokeh by way of a nine-blade circular diaphragm. The range of focal lengths it covers, from wide-angle to normal-length, is nicely situated for everyday and artistic shooting applications. Optimized Lens Design Four aspherical lens elements, as well as the incorporation of five SLD glass elements, help to minimize the appearance of distortions and aberrations throughout the zoom range and provide clear imagery with enhanced sharpness. A Super Multi-Layer Coating also benefits the image quality by reducing reflections and flare and contributing to greater overall contrast and fidelity. Hyper Sonic AF Motor The Hyper Sonic Motor provides fast, quiet, and smooth auto focusing that is well-suited for use with video applications. This AF motor can also be manually overridden at any time by rotating the focusing ring, giving you the ability to fine-tune image sharpness through manual focusing. Constructed using a TSC compound material, this lens is lightweight while also exhibiting notable durability and resistance to environmental changes. An internal focusing and zooming mechanism helps to maintain a consistent overall lens length and a non-rotating front ring facilitates more efficient use of circular polarizers.