drolo61 said:
I have had an intense weekend shooting children's hats for my wife's company.
I use BBF with AI servo to be able to follow the running little beauties. For the first time I have a relatively lower rate of critically sharp images (70-200 2.8 II IS), although working faster than 1/200 and ~ at least 4.0
Cheers
Olaf
I have nothing but praise for the 5D4 AI Servo performance. Even in low light shoots such as a dress rehearsal earlier this week, the keeper rate was reassuringly high. For this particular job I was running four bodies (not all at once!) the 5D4 with 24-70 f/2.8II, 1DX with 70-200 f/2.8 is II, 7DII with 300 f/2.8is and an amazing Panasonic G9 with a brand new 43.5 f/1.7 set to auto iso. All bodies were on AI Servo focus. For a good look, all lens apertures were either wide open or just one click down.
So I'd be inclined to think your low keeper rate is linked to user error. The first thing I see is shutter speed, with the 70-200 you really need to get that shutter speed up a lot, particularly with fast moving children. The 5D4 may have actually focused accurately, but motion blur lost the shot for you. For the job you've described, I'd be using single AF point and keeping that point right on the subject's eyes. At the most, I just might have chosen to expand that AF point to seven in Custom Functions, but I generally only do that for track and field athletics and sometimes football.
I see in your later post you're shooting stopped right down to f/10.
Hmmm, not really the best idea unless you're chasing a certain look, I'd be shooting your project at f/3.5 or f/4 at the most. This has the multiple benefits of blurred out backgrounds, a faster shutter speed and lower iso.
Regarding the keeper rate success at the dress rehearsal, all four cameras were very satisfyingly high. The surprise winner was the recently purchased Panasonic G9 with the 43.5mm f/1.7, (87mm FF equivalent) mostly shot wide open. Interestingly the G9 files comfortably outperformed the 7D MkII at equivalent iso. Next best was the remarkable 1DX, followed almost line-ball with the 5D Mk4 and the 7DII not far behind. This is likely a lot to do with inadequate shutter speed with the 480mm equivalent focal length with the 300mm lens on the x1.6 crop APS-C body.
In all cases I used the default AF servo Case setting.
-pw