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ISO Accuracy

The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). Note that these tests are based on the sRGB JPEG output of the cameras, in accordance with ISO 12232:2006, the standard used by camera manufacturers.

We found that measured the ISO from the Canon EOS 1100D is roughly 1/3 stop higher than indicated across the ISO range - so ISO 100 indicated = ISO 125 measured, etc.

Noise and Noise Reduction (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Note: this page features our new interactive noise comparison widget. By default, we show you the default noise reduction settings of the camera tested, and three other models of the same class. You can select from all available NR options, and from other cameras. The 'tricolor' patches beneath the familiar gray/black/portrait images are taken from the same test chart, and show how noise impacts upon blue, green and red areas of a scene.

In the entry-level bracket of the DSLR market the competitors with APS-C sensors are, from a noise performance point of view, fairly close. Only the Panasonic G2, which comes with a smaller Micro Four Thirds sensor, is visibly noisier than the rest in this comparison.

At default settings the Canon EOS 1100D maintains a pretty good balance between detail and noise reduction up to ISO 1600 after which the effects of noise reduction clearly kick in. Images taken at higher sensitivities are softer and show visibly more chroma noise, but are still very usable for smaller output sizes. At those higher ISOs the Nikon D3100 and Pentax K-r manage to maintain more detail at very similar noise levels but the differences are only small. Of course these two competitors also offer higher maximum sensitivities at ISO 12800 (Nikon) and 25600 (Pentax). The results aren't pretty but these settings might be useful in emergency situations.

Even with noise reduction switched 'Off' (custom function C.FnII-4) the camera still applies noise reduction to the image and you get the same noise reduction 'jump' from ISO 1600 to 3200 as in the default 'Standard' setting. You'll have to shoot RAW if you want to get the most detail out of your high ISO files.

RAW noise (ACR 6.4 RC - noise reduction set to zero)

Here we look at the RAW files processed through Adobe Camera Raw (in this case version 6.4 Release Candidate). Images are brightness matched and processed with all noise reduction options set to zero. Adobe does a degree of noise reduction even when the user-controlled NR is turned off.

The amount of NR applied 'under the hood' is not high, but it does vary by camera (Adobe is attempting to normalize output across different sensors), so inevitably we are still looking at a balance of noise and noise reduction, rather than pure noise levels. However, the use of the most popular third-party RAW converter is intended to give a photographically relevant result, rather than simply comparing sensor performance in an abstract manner.

With noise reduction turned down to zero in ACR all the cameras here show some signs of noise, even at base ISO. Up to ISO 1600 the APS-C cameras in this comparison are virtually on par. At higher ISOs the Pentax applies noise reduction to its RAW files which is clearly visible in both the graph and samples. Again the Micro Four Thirds Panasonic G2 is significantly noisier than the APS-C competition.

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