I just reread your conversations and I thought that you were talking about the 2x extender, sorry! Lens with the 1.4x will focus but with the 2x on the 70-200f4, or any lens above f2.8, the auto-focus will not work unless you're using the 1 series body.

Hanuman - I don't think I would use the 2xiii on the 70-200 f4 is even with my 1d4, but I do love it on the 70-200 f2.8 ii. Totally agree that the 70-200 is much better at 100mm-200mm than the 100-400mm which is why I guess I justify keeping both!

I agree with you and I like your choices sperraglia! On my trip the 70-200 f2.8 mk2 with the 2x mk3 extender worked OK but on a few occasions I wish that I had the 100-400L! I will be trying out the 28-300L, love the range here, next week and will compare that to the 100-400L. Or.. perhaps I will wait for a few more months as I here that the 1d5 with 30+megapixel and a few mk2 versions of the L lenses will be coming out.

Hanuman - My major decision right now is to stick with the 800mm or go for the 600mm II. I know it is not a traditional choice for safari but loved the 800mm in Kenya. Did a whole lot more birds than I thought because I had the lens for it.

Just the mere mention of an 800 or even a 600mm makes my back ache!

Hanuman - some things are worth the pain and it was nice to have the tent closest to the trucks1