Canon 1DX Mark II High ISO NR
Canon 1DX Mark II High ISO Noise Reduction
The Canon 1DX Mark II's four High ISO Noise Reduction settings ("High, "Standard", "Low" and "Off" (Disable)) provide good flexibility in choosing how you want to make the trade-off between subject detail and noise levels.
See for yourself how the Canon 1DX II's "Standard" and "Off" High ISO NR settings compare to RAW without noise reduction under daylight-balanced lighting. (Note that these RAW images also have no sharpening applied, so they are softer than camera JPEGs at low ISOs.) Click on any of the crops below to see the corresponding full-sized image. Since the Canon 1DX II user manual states noise reduction is applied at all ISOs, we've included crops from the base ISO on up.
High ISO noise reduction seems to kick in already at base ISO, where it already starts to impact fine detail in our difficult red-leaf swatch. And as is usually the case, the Off setting is not truly off, applying strong chroma noise reduction, but leaving a lot of the luma noise behind. At intermediate to high ISOs, we would probably elect to shoot with the Low or even the Off setting, to better preserve fine detail. As you can see, sensitivities above the maximum native ISO of 51,200 or perhaps extended ISO 102,400 are very noisy, but at least the Canon 1DX Mark II doesn't offer the ridiculously high extended ISOs the Nikon D5 does.