AdrianWarren.com: Reviews: Canon EOS 400D
Most modern digital cameras have the ability to vary their sensitivity on a frame by frame basis. The sensitivity is measured in ISO/ASA steps, the same sensitivity measurement previously used for film. To achieve a change in sensitivity the camera increases the gain on the amplifiers on the sensor (think turning up the volume), unfortunately whilst this boosts sensitivity it also amplifies any noise. To counter the noise most cameras implement some form of noise reduction. Overzealous noise reduction can lead to a loss of detail, resulting in images that look almost plastic.
Test conditions
| EOS 400D - JPEG, 100% crop | EOS 350D - JPEG, 100% crop | |
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| ISO100 | ||
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| ISO200 | ||
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| ISO400 | ||
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| ISO800 | ||
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| ISO1600 | ||
Throughout the entire sensitivity range both cameras handle the test pattern well in JPEG mode. Whilst there is a little noise creeping into the images at the higher ISO settings, it's minor. Troublesome chroma (colour speckle) noise is particularly low. There is a little softness creeping in at ISO1600, but the results remain usable despite that.
The original samples were shot as RAW+JPEG, so the samples below are from the same original images as those above. These are converted from the RAW files with DPP, with no noise reduction applied. This gives a better idea of the underlying sensor quality, rather than day to day shooting quality.
| EOS 400D - RAW, 100% crop | EOS 350D - RAW, 100% crop | |
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| ISO100 | ||
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| ISO200 | ||
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| ISO400 | ||
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| ISO800 | ||
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| ISO1600 | ||
As you can see, there's more detail present in the RAW files than we saw in the JPEG. At higher sensitivities there is some noise creeping in. From these samples I'd give the 350D a half a stop advantage in terms of outright noise, but the 400D is capable of resolving slightly more detail in all the crops. Both cameras appear to be applying noise reduction at a firmware level though, based on the relatively low amounts of chroma noise.
Incidentally, you may be seeing some vertical banding; this isn't an issue with the camera, it's a pattern in the target.
Indicated sensitivity (ISO) on the x-axis, RAW luminance standard deviation of the grey swatch on the y-axis. Using RAW file data.
Indicated sensitivity (ISO) on the x-axis, chroma (colour) standard deviation of the grey swatch on the y-axis. Using RAW file data. Chroma = A+B/2
