Northstar said:Mack...you wrote "My keeper rate was pretty low with this type of shot"
Like you, my keeper rate with 1dx and 300 2.8 at 2.8 has always been fairly low with this type of shot. (subject coming straight towards me)
I almost always use AF case 1 with 4 surrounding points.
Does anybody have a high keeper rate with this type of shot when shooting at tele range like this and 2.8? Or is it just something you learn to live with?
I don't know what your keeper rate is but I can honestly tell you that my keeper rate is not that low. There are not so many photos I have to reject for this reason. My keeper rate is for sure more then 90%. However I did find out that AF mode 4 is mostly giving me a higher keeper rate then mode 1. This is certainly the case with jumping. I mostly use 1 central point AF with 4 point expansion, the less the faster. Also the central point is always a cross-type AF point. I can't tell you right now if the keeper rate on the 1Dx is better then the 5D3 (I know it should be), but I only have the 1 Dx about 2 months and didn't have the time to make a good comparison, but for sure the AF of the 1Dx behaves almost the same as the 5D3 with the exception of color recognition which is a surplus.
Look for the photo here below (FL-20140330-_5D35972-) on page 2, right after that you can find a range of 18 photos and they were all in focus.
Remark: I just did see that these photos are made with f4.5. That day I really needed to go to mostly f4.5 as otherwise the photo was overexposed. I did see that I also could have increased the shutter speed to 1/4000 instead of 1/1000 to get more or less the same result. My experience with in focus of the 300mm is very good. But it took some time. Yes you MUST afma your lens on your body, and also the combinations of the extenders, to use it on 2.8. I tried several things, but at the end I was only satisfied with the result of Focal software. I like that software very much as it is based on statistics as every movement of the AF system is different due to tolerances