The new family member arrived yesterday, and I was able to get out today on an owl shoot to run it through some paces. This Great Grey was a fair ways away (I should have used an extender on the 500 f/4), but it served as a useful test subject nonetheless. I had all the focus points activated for auto tracking, and when the owl took off to catch a mouse I was quite impressed at how the camera could follow it in spite of the cluttered background. I'm sure my "old" Mark II would have lost tracking against those trees -- it can never seem to lock on in those situations. The image quality is decent for sure, although I can't say how much better it might be than the Mark II.

1/1600 sec @ f/4, ISO 500

1/1600 @ f/5.6, ISO 1000
Flying the wrong way of course, but useful as a test nonetheless

1/1600 @ f/5.6, ISO 1250

The new focus system is quite impressive. The focus points are smaller, so there doesn't appear to be a need to ever have to use the micro-focus mode (where just a tiny dot is activated for precision focusing). The AF-ON trackpad is rather slick. You first press the focus selection button, then slide your thumb over the AF-ON button to move the point around. Pressing the AF-ON button in then locks the selection in. It's certainly better than using the toggle selector, but it will take some getting used to since I have to re-train to this new procedure.

The speed and buffer size are simply ridiculous. The Mark II was already excellent in that regard, but this is just beyond nuts. I could hammer the shutter down for as long as I wanted, and the buffer counter in the viewfinder wouldn't even budge from 99. Luckily I got a 512 GB CF Express card as part of the early bird deal, because I think I'm going to need lots of storage .