http://www.lensrentals.com …oint-single-shot-accuracy
http://www.lensrentals.com …-ii-1-vs-2-and-old-vs-new
http://www.lensrentals.com …lity-part-3a-canon-lenses
http://www.lensrentals.com …ity-part-3b-canon-cameras
Very long, but informative and interesting read...
I think the most interesting bit of it is in Part 3b, Wherein he basically found out something i think many of us always -assumed- was true, that phase detect AF is "closed loop" IE, Camera tells lens to go to X distance, Lens moves, Lens tells Camera its moved, Camera checks focus is correct
But in reality, until recently, its in fact an open loop system, your camera tells the lens to go to X distance and thats it.... Which means it was basically a guessing game...
But apparently the new 5DIII and 1DX (and to a lesser extent, the T4i) are closed loop systems, which means they have improved AF accuracy over prior models (when using the newer lenses that are optimized for it) Which is kinda interesting and cool...
I dunno its probubly been posted, but i found it very interesting to read... Certainly am not about to declare my 7D is crap at focusing (Because i've used it enough to know its not) but its a little surprising to see just -how- good the new 5DIII's AF is
