I found it interesting he chooses the 200-400 as his only real tele, whilst they are expensive new I have seen secondhand ones for way South of $6,000, still not cheap but if that is the best of the best it isn't that big an investment, heck it's less than a 1DX III. But there is no reason a Tamron or Sigma 150-600 couldn't be used by somebody starting out and that is less than one quarter the price of the used Canon 200-400. Morten Hilmer is an amazing wildlife stills and videographer and he uses the Tamron to capture images every bit as compelling as his Nikon 600mm prime.