whumber, thanks so much for posting those shots. My Canon 2x Mk II died recently and funds don\'t stretch to a Mk III so I\'m going to go for a Yongnuo in the meantime until the Mk III second-hand prices drop a bit*. Your post give me the confidence to give it a shot from Amazon.
Should be able to test with a 600mm f4 and will update you all within the next couple of weeks.
* Here in the UK a second-hand, unboxed, Mk III is still over twice the price of a new Yongnuo.
