ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

The D90 has four Noise Reduction settings, High, Normal, Low and Off - the three active settings have an effect at all ISO settings. These settings do not appear to make any distinction between chroma (color) and luminance noise, so the choice they offer is how much detail you want smoothed away along with the noise, as there's no option to remove only chroma noise and allow the luminance 'grain' to remain. The Noise Reduction Off setting or shooting RAW does allow the use of third-party software to achieve this, however.

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis (note that the standard deviation scale here has been extended 3x compared to the graphs on the previous page).

Noise reduction crop comparisons (ISO 800 - 6400)

ISO 800 NR Off	ISO 800 NR Low	ISO 800 NR Normal	ISO 800 NR High
ISO 1600 NR Off	ISO 1600 NR Low	ISO 1600 NR Normal	ISO 1600 NR High
ISO 3200 NR Off	ISO 3200 NR Low	ISO 3200 NR Normal	ISO 3200 NR High
ISO 6400 NR Off	ISO 6400 NR Low	ISO 6400 NR Normal	ISO 6400 NR High