A Late Day Gallop
I frequently use galloping horses for lens autofocus testing as they are challenging for the camera, lens - and me. The Canon EF 600mm f/4 L IS II USM Lens is very impressive in its AF capabilities - and is able to track the speeding horse until only half of the rider fits in the frame.
Camera and Lens Settings
600mm f/4.0 1/1600s ISO 250 3840 x 5760px