600mm vs 400mm for bird and wildlife photography?

I talk about the 3 reasons (the 3 "W"s) why I am not buying the new Nikon Z 600mm f/4 lens. Comparing with Sony A1, Canon R5, Nikon Z9 with their respective 600mm f/4 lenses. Follow my IG: instagram.com/tinmanlee Join my VIP list and check out my gear list: https://linktr.ee/tinman Website: tinmanlee.com