Is the Sigma 24mm f/1.4 DG HSM Art Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 24mm f/2.8 test image. Observe the contrast and resolution of these results.
Is the Sigma 24mm f/1.4 DG HSM Art Lens set to 24mm f/2.8 sharper than the Canon EF 24mm f/2.8 IS USM Lens set to 24mm f/2.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.