Quote Originally Posted by DavidEccleston View Post
AF tracking depends on a lot of variables. Focus tracking at short distances is hard. Hopefully Brant can fill in some extra details on what sort distance and lens combo was failing. A pug is on the smaller side, so may require an even longer focal length to fill a reasonable portion of the frame without being "too close to track" for the same zoom lens.

From my 7D, 7DII, and 1DsII experiences, tracking a dog running towards the camera, in good light:
with a 50mm lens... missed AF is expected.
with a 85mm lens... AF is hit and miss.
with a 200mm lens... missed AF is unexpected.

From my experience with a Rebel T1i, tracking a dog running towards the camera, in good light:
with a 50mm or 85mm lens... missed AF is expected.
with a 200mm lens... AF lags. Expect blurred heads and sharp tails.
Actually, it was you and your dogs that I was thinking of. As I was reading that, I was picturing the Pug running with you dogs on their agility coarse. I know that is letting the imagination get the best of me, but that is what made it seem all the more funny.

Regarding the statement from Brant, I also assumed there was some expectation that the AF should perform in the conditions he threw at it (although he did say it was low light), or he would not have made the statement. But I was reading into it and making an assumption.

My daughter has her dogs at my house, and one of them is crazy fast. It took me a few burst on the 1Dx to somewhat get the hang of it, and was eventually able to get a couple of decent shots (70-200mm at f/2.8). Having said that, I must admit I did not get near the kind of shots you get and probably not the keeper rate. But a pug? Cute... debatably yes; but athletically fast... I don't think so. I guess I agree, in that I would be curious as to what lens was used, but the 5D IV should have better focus than any of the cameras you listed.

By the way, the ability to move focus points around and have the metering follow your focus point would really be great for you when shooting your dogs. The 1Dx does that. If you are interested in a low shot count 1Dx, I have one I could be talked into parting with. I think your dogs could even stress the abilities of the 1Dx.

Pat