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ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

The GF1 has five levels of noise reduction from -2 to +2. The graph below shows the effect of the various settings from ISO 800 upwards. As you can see the difference, even between the extreme settings, is fairly small, particularly at ISO 800.

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 is magnified 3.5x compared to the graphs on the previous page).

In-camera High ISO noise reduction

  ISO 400 ISO 800 ISO 1600 ISO 3200
-2
-1
0 (STD)
+1
+2

Although the difference between -2 and +2 isn't huge, it does give you some control over whether your JPEGs are a bit noisy or very noisy at the highest ISO settings. We'd recommend using -1 or even -2 most of the time, as the higher settings tend to smear color and produce grainy, but washy results.

Noise reduction and fine detail

The biggest issue with noise reduction - especially luminance noise reduction - is that in the process of blurring away the noise it can also have a very destructive effect on the detail in an image, particularly the fine, low contrast detail you might find in hair, fur or grass. To better judge the effect on fine detail lost due to noise reduction we have shot our lovely model and produced crops from the feathers in the image.

To check the effect of noise and noise reduction on low contrast detail we shoot our new studio setup at various ISO and noise reduction settings, then crop an area that's challenging to any camera. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.

Raw vs in-camera JPEG noise reduction low contrast detail comparison

The crops below clearly show the destructive effect noise reduction has on fine detail and texture as you move up the ISO range, though a glance at the raw shot shows just how much noise there is to deal with at the highest settings. At ISO 400 and above there is a small detail advantage to turning the noise reduction down, though obviously this comes at a cost. The default setting (zero) smears color detail at high ISO settings, and the results are far from pleasant.

  ACR RAW NR OFF JPEG NR-2 JPEG NR-standard JPEG NR+2
ISO 100
ISO 400
ISO 800
ISO 1600
ISO 3200
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