A lens by far! Heavy and solid construction, delivers razor sharp images and the AF is extremely fast and can handle without problems following the fast subjects. Wonderful bokeh! This is my personal favorite that I use in places where I need to reach the subject and where the light is often a little worse. Clearly, an alternative to the Nikon 200-400mm f / 4 which is a bit heavier and 155mm long.
With a tele-2X gives the 400mm with aperture 4 and is great for wildlife photography and sports photography. Provides cruelly sharp pictures and is absolutely worth the money that quickly pays for itself if you have photography as work.