Nikon D4S High ISO NR
Nikon D4S High ISO Noise Reduction
The Nikon D4S 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 D4S 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 D4S manual does say when Off is selected, noise reduction is only performed at ISO 6400 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 3,200. At higher ISOs, the trade-off between detail and noise can easily be seen, with the default setting providing very effective chroma noise reduction, though luminance noise is a little high at very high ISOs, exacerbated by strong default sharpening. You can also see the Off setting still applies some minimal noise reduction at ISO 6,400 on up, just as Nikon says.