Here's a quick question... when shooting horse riding coming towards you... do yall try for both the horse's head/face and the riders to both be in focus or do you aim for one or the other... and if the other is blurred... it's blurred.
I know the distance along at which we are shooting will usually have both within the depth of field... but it is something I've been wondering.
As you have rightly identified, horse and rider combinations coming towards you are long, so you need an aperture that is going to cover that depth of field. When shooting show jumping I always zone focus; you know exactly where the horse is going to be at the time you want the picture. For dressage I use tracking because although in theory you know where the horse is going to be if you know the test there is nothing specific to pre focus on, and getting the right leg position requires taking pictures in many different places.
So for zone focus I know that I am placing the point of focus roughly between the rider's body and the horse's head, with enough dof to cover both. With tracking AF I am trying to focus on the rider, but with enough aperture to cover both. Also animal fur can be notoriously difficult for the AF to lock on to. If you want to achieve minimum dof it takes a little practice to know what aperture / focal length / distance combination you can get away with.
With the pictures I've posted here if either the rider or horse's head was oof the picture would be a dud. In the pictures of Heather I was really pushing it with an 85 @ 1.8. If you saw a big version of the pictures you might find that the horse's head is not as sharp as the rider's. With the picture of Kelly shot with the 135 I had to use a smaller aperture.