Thanks for the kind words.
There were multiple challenges here:
- the movement of the horse isn't 100% predictable,
- the AF can lock on the head of the horse instead of locking on the rider,
- the crowd surrounding me was moving a bit, forcing me to adjust my position which isn't easy with a long lens and monopod.
The first thing is to know where to stand, which involves knowing the discipline and you equipment well. These events get very crowded and I had no particular accreditation giving me special privilegdes which forced me to position myself 2 hours before the start of the event. There was no way I could have moved more than 50 cm after that without generating a lot of frustration among the people standing around me.
Then the key is to select the right AF mode (here a mix of group AF and single point depending on the image) and to track the rider well. I used a monopod of course with the RRS monopod head which I find to be best for such applications. Still, success ratio isn't any close to 100% if you try to frame tight. Few images are completely out of focus, but few are 100% perfect.
Using a long lens (400mm here) helps with framing since you get to shoot the subject more from the front with less angular velocity.
In this context I find my equipment (D750 and 400mm f2.8 E FL) to perform well from an AF standpoint, even if I find the AF points of the body a bit too centered. Faster frame rates and a deeper buffer would also help. I will most probably invest in a D5 for such images.
Voila.
Cheers,
Bernard