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.
The Canon EOS 600D's measured ISO is within +/- 1/6 EV of the indicated ISO, across its entire sensitivity range.
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.
This is the fourth time we've seen this sensor, and not surprisingly it behaves pretty much the same in its 600D incarnation as in previous cameras such as the 550D (the noise graphs overlay almost exactly). This is no bad thing at all - the 600D maintains a good balance of noise and detail across the ISO range, and delivers results which stand comparison with any of its peers.
At standard settings fine detail is well retained at ISOs up to 1600, after which point the effects of noise reduction kick in quite noticeably. Higher ISO settings show a rapid drop-off in detail as the noise reduction attempts to deliver an acceptable image, but even so the 600D doesn't perform obviously worse than other cameras at a similar price level.
RAW noise (ACR 6.3 - noise reduction set to zero)
Here we look at the RAW files processed through Adobe Camera Raw (in this case version 6.3). 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.
The similarity of both the figures and the appearance of these crops suggests they tell us as much about Adobe's ability to normalize the various cameras' outputs as about the cameras themselves. But again it's clear that the 600D keeps pace with the competition, despite its relatively old sensor, and the main difference in the comparison is due to the K-r's application of noise reduction to raw files at ISOs above 1600. Even at ISO 3200 the 600D's detail retention is impressive, but at 6400 noise is beginning to take over the image, and at 12800 the results illustrate graphically just now much noise the cameras' JPEG engines are having to contend with.
The graphs again confirm that, in terms of measurable noise at least, the 600D gives near-identical results to the 500D, 60D and even the much-more-expensive 7D, which is a pretty positive result.