Is the Sigma 40mm f/1.4 DG HSM Art Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 40mm f/1.6 test image. Observe the contrast and resolution of these results.
Is the Sigma 40mm f/1.4 DG HSM Art Lens set to 40mm f/1.6 sharper than the Tamron 45mm f/1.8 Di VC USD Lens set to 45mm f/1.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.