At higher ISOs, the trade-off between detail and noise can easily be seen. You can also see the Off setting still applies some minimal noise reduction at ISO 3200 and above, just as Nikon says.
Below are the results of our optical tests with the optional Nikkor AF-S 50mm f/1.8G Special Edition kit lens. The Nikon Df is available bundled with a Nikkor AF-S 50mm f/1.8G Special Edition "kit ...