Rented a Nikon D5 and a 400mm prime. Used a tripod with a gimbal mount. Back button AF, AF-C, 9pt. 1/2500, f/6.3, Auto ISO. Even when the focus point is where it should be the image is not sharp. Same problem when hand holding with the 70-200 f/2.8 lens. I can't figure out what I am doing wrong?
I didn't find the right solution from the Internet.