Two days ago i bought a used EOS M as a second body - it was dirty cheap and coming with an EF adapter so i decided why not to try it for the cases i don't want to carry my heavy 50D. After doing some shots i was amazed to discover that even though the EOS M is focusing slower and is sometimes hunting and struggling to get focus the actual photos with some of my lens are better than with my 50D.
Below i have uploaded 2 100% crops from untouched raw files (sorry for the difference in size, i used the lame windows snipping tool). They are taken with Sigma 10-20 lens wide open at 10mm. The upper one is from my 50D and the lower is from the EOS M. The crop from the EOS M is quite better than the one from the 50D. I'm wondering - is this due to focusing issues which can be compensated with the built in focus correction in the 50D or there's some other issue? Or there's no focusing issue, it's just the age of the 50D sensor vs the newer one found in the EOS M (which i honestly don't believe).