ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

ALike most recent EOS models the Mark III offers optional 'High ISO Noise Reduction' which can be enabled via C.Fn II-2. As you can see from the graph below this appears to apply stronger chroma noise reduction while maintaining luminance detail (it made almost no difference to luminance noise). This leads to images which have less noticeable color blotch type noise and more film like grain, the only downside to using this option is reduced buffer space in continuous drive.

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

In-camera High ISO noise reduction Off / On vs RAW (ISO 800 - 3200)

To get an idea of how much noise reduction is being done in-camera we've also included a straight Adobe Camera Raw conversion (with all noise reduction set to zero) in this comparison. Shooting raw and carefully processing to remove the chroma noise produces images with a quite pleasant fine grained almost film-like appearance that is perfect usable.

ISO 800 ISO NR Off ISO 1600 ISO NR Off ISO 3200 ISO NR Off
ISO 800 ISO NR On ISO 1600 ISO NR On ISO 3200 ISO NR On
ISO 800 ACR 4.5
Noise Reduction Off
ISO 1600 ACR 4.5
Noise Reduction Off
ISO 3200 ACR 4.5
Noise Reduction Off