Way back in 2007 Canon was the undisputed DSLR KING, their super fast; accurate 1D MkI followed by MkII were outclassing all the other pro DSLR!
Then came the MkIII, with their "better" revamped AF system; has so many problem that left hundreds of irritated loyal Canon users cursing.
With the pending Beijing Olympics and the newly launched, virtually flawless Nikon D3; pro shooters left in droves for the "Dark Side" and the rest is history.
From 2007 Canon lost its dominance of the DSLR!