Nikon Df High ISO NR
Nikon Df High ISO Noise Reduction
The Nikon Df offers four High ISO Noise Reduction settings: Off, Low, Normal (default), and High, allowing you quite a bit of flexibility in choosing how you want to make the trade-off between subject detail and noise levels in JPEGs. The Nikon Df manual doesn't say at what ISO High ISO Noise Reduction begins to be applied, so we've included crops from ISO 50 on up here. Note that the Nikon Df manual does say when Off is selected, noise reduction is only performed at ISO 3200 and higher, and the amount is less than Low.
See for yourself how the Normal and Off settings work compared to RAW files with no noise reduction (or sharpening) applied. Click on any of the crops below to see the corresponding full-sized image.
As you can see, the Normal and Off high ISO noise reduction settings have little effect below ISO 3200. 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.