All the info I have gathered is that its a great lens and pretty sharp however it won't be as good with a tc as your 300 f2.8. I was considering one for a while and may still get one as the zoom is invaluable to me, especially when working from a hide.
super shot Martyn. I am used to the 300 with 2TCIII for planes but it is too restricting due to the fixed focal length and can often miss the shot or cut the tail or nose off! Certainly the 1.4TC at the 400 end would being me back into the same field as the prime. Have been offered a used Mk1 200-400 - worth considering or not?
merv:bang:
Just seeking general opinions on the 200-400 lens to see if worth considering to replace the 300/2.8 prime. Merv
Is there no hiding place from you Tommy and Tony. I feel I can do nothing without you knowing. Get into PC so that I can get some decent advice about the iMac, every time I call you're not there!
Thinking of selling the 300/2.8 prime and getting the 200-400 if I can get a sensible price.:bonk:

Martyn thats some article by Thom Hogan, very comperhensive. Havent had time to read it all yet but frightened it might put me off. I just feel keeping the 300 prime is cramping my style