Obviously, this will also depend on the steadiness of the photographer as well. In summary, the Canon EF 400mm f/2.8L IS III USM lens is a superb performer. You can view additional images in the ...

(From Canon lens literature) Designed to satisfy the discriminating needs of sports and wildlife photographers, the EF 200–400mm f/4L IS USM Extender 1.4X is a high-performance super telephoto ...