It appears that Canon has reached the limit of what is sensible, in terms of megapixels on an APS-C sensor. At a pixel density of 4.5 MP/cm² (40D: 3.1 MP/cm², 1Ds MkIII: 2.4 MP/cm²) the lens becomes the limiting factor. Even the sharpest primes at optimal apertures cannot (at least away from the center of the frame) satisfy the 15.1 megapixel sensors hunger for resolution. Considering the disadvantages that come with higher pixel densities such as diffraction issues, increased sensitivity towards camera shake, reduced dynamic range, reduced high ISO performance and the need to store, move and process larger amounts of data, one could be forgiven for coming to the conclusion that at this point the megapixel race should probably stop. One consequence of this is that the 50% increase in pixel count over the 40D results in only a marginal amount of extra detail.
We're by no means saying the 50Ds image quality is bad but it's simply not significantly better than the ten megapixel 40D. In some areas such as dynamic range and high ISO performance it's actually worse and that simply makes you wonder if the EOS 50D could have been an (even) better camera if its sensor had a slightly more moderate resolution.
The EOS 50D has to stand its ground in a highly competitive bracket of the DSLR market. It is currently almost $500 more expensive than the 40D, almost $500 more expensive than the Nikon D90 and for an extra $100 you can bag yourself a Nikon D300. Looking at the specification differences between the EOS 40D and our test candidate it appears you pay quite a premium for the 50D's extra megapixels and as we've found out during this review you don't get an awful lot of extra image quality for your money. The Canon EOS 50D still earns itself our highest reward but considering its price point and our slight concerns about its pixel-packed sensor, it only does so by a whisker.
