At ISO 100, noise is barely visible
The same is true of ISO 200, with just a slight increase.
Images show a hint of a graininess at ISO 400, but not to any great extent.
Some distortion begins to appear around finer detail at ISO 800, although once again it's not to the detriment of image quality.
Fine detail softens a touch due to noise reduction at ISO 1600, though once again the high setting is usable.
ISO 3200 shows definite smudging of fine detail and overall softening, although it is far from unusable.