Canon 50D High ISO NR

Canon 50D High ISO Noise Reduction

Unlike the Canon 40D which only offered "On" and "Off" settings, the Canon 50D offers four high ISO noise reduction settings, allowing you quite a bit of flexibility in choosing how you want to make the trade-off between subject detail and noise levels. It's not clear that the "off" setting truly eliminates the noise processing altogether, but it is true that it leaves a lot of fine/subtle subject detail there for you to work with. The combination of shooting with NR turned off and using a good noise-filtering program after the fact can produce very clean images with lots of fine detail in them. (And of course, the 50D's RAW files have no noise-reduction processing applied to them at all, adhering to the true philosophy of RAW shooting.)

See for yourself how the noise reduction works under daylight-balanced lighting. Click on any of the crops below to see the corresponding full-sized image.

The above crops show the effects of the four levels of high ISO noise reduction available on the 50D, under our studio HMI lighting, which has a daylight white balance. As noted above, the 50D gives you a range of options for balancing image noise vs subtle detail. Compared to the Off setting for high-ISO noise reduction, the Low option appears to primarily affect chroma noise, leaving luminance noise more or less alone. Standard attacks both luminance and chroma noise, but at increased cost to fine detail in areas of subtle contrast. (See the red fabric swatches in the crops above.) Finally, Strong flattens out noise considerably, but at a heavy cost to detail in low-contrast regions of the image.

As megapixel counts have risen and the pixels thus become smaller, Canon has managed to maintain surprisingly constant high-ISO performance, through improvements in sensor cell layout and microlens design, as well as in their noise-reduction processing algorithms. So how does the 50D compare to the 40D? See the crops below:

The above crops compare the 50D (top row) versus the 40D (bottom row) of each set. As mentioned above, the 40D only offers "On" and Off" high ISO NR settings.

Here we see the impact of the 50D's higher resolution sensor (with the smaller pixels that implies) on high-ISO performance. At any given ISO level, JPEG images from the two cameras contain roughly similar levels of noise, and at ISO 800, the Canon 50D's images arguably hold a bit more detail in low-contrast regions than do those from the 40D. At ISOs higher than 800 though, while the 50D holds good detail in high-contrast objects (such as the fine lines on the round scale), it trades away progressively more subtle detail, and is considerably worse than the 40D in this regard. (Check out the red fabric swatch at ISO 3,200; the loss of detail there with standard noise reduction applied is pretty profound.)

Canon and Nikon perpetually try to top one another. Sometimes Canon has been ahead, at other times Nikon has been on top. So how does the Canon 50D compared to Nikon's D90? The crops below compare the 50D (top row) versus the D90 (bottom row) in each set.

People tend to react to noise rather differently, but to our eyes the images above show pretty clearly that Nikon currently has the upper hand in the high-ISO derby. Of course, the D90 has about 20% fewer pixels than does the Canon 50D, but the actual difference in both linear pixel dimensions of the images and the sizes of the pixels themselves are fairly minor. (The Canon 50D has only 10.8% more pixels horizontally than does the D90, so the difference in resolution between the two cameras amounts to relatively little in actual practice.) We have little doubt that Canon will catch up (and perhaps surpass) Nikon at some point in the future, but for the moment, Nikon beats Canon on high-ISO noise performance, at least in this price bracket. Results compared to the more expensive Nikon D300 are very similar.