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Message: <blockquote data-quote="stephenB" data-source="post: 1542802" data-attributes="member: 23668">I've recently acquired a 50D as a replacement for my 40D, as part of a complicated insurance claim/saga (another story!)I have now made some initial quantitative measurements of the noise levels on raw images from this camera, and compared them with the values from the 40D, and my older 350D.I am dismayed by the results for the 50D - the noise appears to be almost exactly one stop worse than for my 350D. This means that the noise on the 50D at ISO 400 is very similar to that of the 350D at ISO 800, and similarly for the 50D at ISO 800 the noise is the same as on the 350D at ISO 1600! Not good! Here are some details to substantiate these findings - see especially the attached graph. To make these measurements, it is important to note that I used images in raw format from all 3 cameras, and for the 50D I disabled all the settings which might affect the basic output from the sensor. So I made sure the following were off:* high ISO speed noise reduction* highlight tone priority* auto lighting optimiser(i.e. CF II functions 2, 3 & 4). This is effectively the same as for the 40D and 350D, and so the raw images should be basically what is coming off the sensor, with minimal processing. In other words a like for like comparison between the cameras.The graph shows noise levels measured for all 3 cameras as a function of image grey level (brightness). All show a characteristic decrease in noise for higher image brightness, and all show the expected increases as the ISO setting goes up. Note how the lines for the 50D agree very closely with the 350D but one ISO setting higher. It is also interesting to see that the 40D out performs the 350D by about 1/2 stop in these terms, which makes the comparison between the 40D and 50D even worse!To make these measurements I took slightly out of focus pics of a grey scale test chart I had printed out for the purpose (see pic attached), and then used some free software to measure the standard deviation of the image values in small (30 x 30 pixel) regions for each step in the grey scale. I'm wondering if there could be something wrong with my 50D, but I suspect not. I note that the DP review site shows a 50D raw image which is visually substantially noisier than a 40D image. It also has the interesting comment that "Considering the 50D's much more tightly packed sensor (4.5 MP/cm² vs 3.1 MP/cm² on the 40D) this comes hardly as a surprise. It would have been unreasonable to expect Canon's engineers to overcome the laws of physics."Indeed! In fact, the higher noise levels on the 50D compared with the 350D are almost exactly what would be expected given the factor of 2 difference in the number of pixels on the sensor [theoretically, if the noise is dominated by photon counting statistics, then halving the area of the pixel will increase the noise by sqrt(2), which is exactly the same factor that increasing the ISO setting by one stop produces].But many other web sites appear to suggest that the 50D is no noisier than the 40D, or is only slightly worse. But these are generally based on qualitative comparisons of general images - useless for assessing noise levels properly in my opinion! I suspect the key to all this may be switching off the "High ISO noise reduction", which is suspiciously set on "Standard" by default. This is likely to low pass filter the image, and reduce noise at the expense of a loss of sharpness. So have Canon set it up like this to try to mask the basically poor noise performance of the 50D sensor, by any chance?I'd be interested in any comments from others on this. Do other more experienced users of 50D raw images suffer from high noise levels?</blockquote>

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