Is the Nikon 200-400mm f/4G AF-S VR II Nikkor Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 680mm f/7.1 test image. Observe the contrast and resolution of these results.
Is the Nikon 200-400mm f/4G AF-S VR II Nikkor Lens set to 680mm f/7.1 sharper than the Canon EF 300mm f/2.8L IS II USM Lens set to 420mm f/5.6? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.