Crazy question: I am the proud owner of a Leica M240 (with lenses) which I absolutely love. However, it's not great for taking nature photos, especially of skittish, faraway animals. I would like to invest in a DSLR and I am trying to decide whether the Canon Eos5D Mark III is the way to go (or the comparable Nikon: D810?) is the way to go. I had a Nikon system (D200) a number of years ago and was not overly impressed. Thanks.
While I can't speak about how skittish animals may affect the auto focusing, I can speak about the 5d Mk III auto focusing. As grandfather called to photograph my grand children's various sporting events, I utilize the 5d's ability to change the manner in which it auto focuses. It is able to shift the focal point to the item moving in front of the point of focus, or to change to accommodate suddenly moving players in the view finder.
Since many of the sporting events are inside, such as basketball, the shutter speed is not often optimal. Utilizing the various AF allows me to get the shot blur free because it changes the point of focus.
Additionally I usually use center focus, but at a basket ball game, the 63 points of focus combined with the variable AF means my photos are clear and far more interesting than if I simple focused solely on my grandson.