The Sigma 17-40mm f/1.8 DC Art Lens for Sony E-Mount is a premium APS-C zoom lens offering a constant f1.8 aperture across the entire focal length. Its advanced optical design features 17 elements in 11 groups, including four SLD and four aspherical elements for precise correction of aberrations. With an internal zoom, HLA linear autofocus, two AFL buttons, and a dedicated aperture ring, it is ideal for hybrid photo and video use. The lens offers image quality on par with a prime lens, fast, silent AF and a compact design, making it ideal for both stills and video content. It is compatible with Sony APS-C mirrorless cameras. The constant maximum aperture of F1.8 makes it ideal for low-light environments and night scenes, as well as for expression using large bokeh. This lens is portable, durable and versatile.