One way to create differentiating photographs is to use an extreme lens. While the Sigma 12-24mm f/4.5-5.6 DG II HSM Lens' max apertures are not close to being considered extreme, its incredibly wide full-frame focal lengths are. No other full frame compatible lens offers a rectilinear focal length this wide. The 12mm focal length provides an extreme angle of view while the overall 12-24mm range proves very useful. In addition, this is a nicely-designed lens that delivers very good image quality.