Sigma's third generation 12-24mm f/4 DG HSM Art Lens, available here with a Canon EF mount, refines their ultra-wide arena and delivers an image with little distortion and with a high resolution for crisp photos with a modern full-frame digital image sensor. A member of Sigma's Art series, it boasts high image quality which is helped out by the use of FLD and aspherical elements, including an 80mm large-diameter molded glasses aspherical lens, that minimizes aberrations and distortion. Furthermore, it uses a Super Multi-Layer coating that minimizes flare and ghosting. Benefitting handling, the 12-24mm is equipped with a Hyper Sonic AF motor with an optimized algorithm for speed and accuracy. The lens also offers a large focusing ring with full-time manual override settings for quickly making adjustments. A rounded 9-blade diaphragm improves image quality by helping create smooth bokeh while the lens is constructed from a lightweight and durable thermally-stable composite. Also, the 12-24mm has a brass bayonet lens mount and is dust- and splash-proof. And, it is fully compatible with Sigma's USB Dock.