Is the Sigma 24mm F3.5 DG DN Contemporary Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 24mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Sigma 24mm F3.5 DG DN Contemporary Lens set to 24mm f/4.0 sharper than the Tamron 24mm f/2.8 Di III OSD M1:2 Lens set to 24mm f/3.2? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.