The Sigma 12-24mm F4 DG HSM | A refines the 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. The Sigma 12-24mm F4 DG HSM | A is a member of Sigma’s Art series, and this lens boasts of 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, the Sigma 12-24mm F4 DG HSM | A uses a Super Multi-Layer coating that minimizes flare and ghosting.