Obviously, there is one less tree on the ranch.
While I mostly used the Canon EF 600mm f/4L IS II USM Lens
on this elk photo trip, there were times when I was really glad to have the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens
readily available. In this case, thanks to the zoom range afforded by this lens, I was able to capture both full-body images and close-ups in rapid succession.
This huge rutting bull rocky mountain elk was in the bottom of a valley that had long been in the shade from the setting sun. He was intently tearing up this tree, which meant that I needed a fast shutter speed to stop the motion. My choice of 1/1000 was certainly not overkill, but I wanted to keep the noise levels down as much as possible. The 5D IV's ISO 5000 looks good enough that choosing an even faster shutter speed would have been a non-issue.
With the upward head angle, it was almost as if I was lighting the 8x7 bull with a huge softbox in the studio.