ISO Sensitivity / Noise levels (contd.)
In-camera High ISO noise reduction
Canon first introduced 'High ISO Noise Reduction' on the EOS 40D. While the first generation of this feature only offered one level of noise reduction, its latest incarnation gives you three (Low, Standard, Strong) which can be controlled via C.Fn II-2. Of course there is also an 'Off' setting. As you can see from the graph below the 'on' options appear to apply a fairly even mix of chroma and luminance noise reduction at all settings. When noise reduction is set at 'Low' its effect is pretty marginal, the 'Strong' setting leads to a visible loss of detail from fairly low ISOs. The 'Standard' setting seems to be, depending on your preferences, a pretty good compromise to work with. Please note that the 'Strong' setting reduces buffer space in continuous drive and that even at the 'Off' setting the JPG engine still applies some noise reduction to the image. If you want to get completely rid of NR shooting RAW is your only option.
Indicated ISO sensitivity is on the vertical axis of this graph, standard deviation of luminosity on the horizontal axis (note that the standard deviation scale here has been extended compared to the graphs on the previous page).
Noise reduction crop comparisons (ISO 800 - 12800)
ISO 800 NR Off |
ISO 800 NR Low |
ISO 800 NR Standard |
ISO 800 NR Strong |
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ISO 1600 NR Off |
ISO 1600 NR Low |
ISO 1600 NR Standard |
ISO 1600 NR Strong |
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ISO 3200 NR Off |
ISO 3200 NR Low |
ISO 3200 NR Standard |
ISO 3200 NR Strong |
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ISO 6400 NR Off |
ISO 6400 NR Low |
ISO 6400 NR Standard |
ISO 6400 NR Strong |
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ISO 12800 NR Off |
ISO 12800 NR Low |
ISO 12800 NR Standard |
ISO 12800 NR Strong |
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RAW noise
Finally let's take a look a the raw output of the EOS50D next to the ten megapixel 40D. Removing any in-camera noise reduction and processing the images using Adobe Camera Raw (without NR) gives us the nearest thing to a 'level playing field' for assessing the relative noise levels of the two cameras' sensors.
The higher pixel count of the 50D will inevitably show more noise at the pixel level. In principle this additional noise might be expected to average out such that the overall image noise is much the same. However the 50D's output at high ISOs shows significant chroma noise, especially in the blacks, which is substantially due to pattern noise (or 'banding'), although this isn't immediately visible in the crops. This is extremely difficult to remove in post-processing, and means that overall the 50D's high ISO output isn't necessarily as useable as the 40D's.
Canon EOS 50D ISO 800 |
Canon EOS 40D ISO 800 |
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Canon EOS 50D ISO 1600 |
Canon EOS 40D ISO 1600 |
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Canon EOS 50D ISO 3200 |
Canon EOS 40D ISO 3200 |
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RAW noise ISO 6400 and 12800
At Hi1 and Hi2 (ISO 6400 and 12800 respectively) the 50D produces significant amounts of noise. Both settings should be striclty reserved for emergency use. If you compare these crops to the 'NR OFF JPG' crops from above it also becomes clear how much noise reduction the 50D's JPG engine still applies even with noise reduction set to 'Off'.
Canon EOS 50D ISO 6400 |
Canon EOS 50D ISO 12800 |
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