Is the Canon EF 85mm f/1.8 USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 85mm f/5.6 test image. Observe the contrast and resolution of these results.
Is the Canon EF 85mm f/1.8 USM Lens set to 85mm f/5.6 sharper than the Canon EF 85mm f/1.8 USM Lens set to 85mm f/2.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.