Was debating about the 2 lenses and after watching this video , I decided to go with the 400mm
Based on my experience , anything longer than 600mm would encounter atmospheric interferences so I hardly shoot beyond that range
On my recent Ecuador birding trip the 300mm + both TCs suffice
The 400mm is lighter , cheaper , and allows me a 800mm reach with 2X and 1200mm at crop mode if needed (Software enlargement could come to the rescue if need more res)
I value the brighter aperture to the extra reach (Owls need light!!!)
I could buy both but for my international travels I prefer to carry only 1 or 2 lenses at most (the 300mm is a must + 1 more)
Great time for birding IMHO
Of course YMMV
Sep 24, 2026 at 08:50 PM
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