As I theorised in my earlier blog – Has Canon lost the plot?, it seems everything I proposed is true…
See dpreview.com’s 50D review – an extract of the summary is quoted here:
“Having said that, in terms of per-pixel sharpness the 50D cannot quite keep up with the better 10 or 12 megapixel APS-C DSLRs in the market. At higher sensitivities the smaller photosites are clearly producing more noise (as shown from our RAW comparisons) and so Canon is having to apply more noise reduction to keep to acceptable noise levels, this of course means a loss of detail from ISO 1600 upwards.
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”