You are correct, I agree, but the 500 f4 L does not weigh 18 kg!


According to Bryan, it weighs around 4.1 kg. Add a pro body which is like 1.2 kg, flash and some other stuff and you get say 5.5 kg... you know what... 6 kg. That is still 1/3 of what this tripod can hold. So it satisfies your 1/3 rule Brendan (which I agree with).