Thanks! I appreciate the feedback. Yes there's a lot to be said for a wide aperture and nice background blur. As I looked through my images, I could see that within a single burst from my 1DXIII, there would be a few shots that are soft and then a few more that are tack sharp. I was trying to hold the focus point on the owl's eye, but there was probably a bit of movement during the burst. Whereas with the R5 and 100-500, every single image in a burst was sharp. That's probably due to the wider depth of field, plus the auto tracking AF holding on the eye.