Thanks. As I mentioned earlier, I haven't had a chance to shoot more than about 50 shots with it because it's been raining here so much. So far, I'm really impressed with the sharpness wide open. I haven't tried to track any moving objects, but hope to get out soon to do some of that. I do not think that I'd want to handhold it for very long because it is pretty heavy. I'm certainly inspired by the shots that you got on safari.
Hi eli72, I shot over 8,500 Images in 4 weeks in Tanzania & South Africa in June with the 200-400f/4, love the Lens, but as you mentioned, you need to be Arnold to hand hold for any length of time, it's heavy. I used a Bean Bag mostly, or my RRS PG-02 on a RRS Monopod Safari rig. I found the only thing I needed to watch was Focus Lock on moving subjects in less than ideal light, unlike the 400f/2.8 this 200-400f/4 obviously achieves focus @ f/4, so you can have more OOF shots in Dim Light than say with the 300f/2.8 or 400f/2.8 but mostly I just found the Lens worked amazingly well. On a couple of Cheetah Kills, +80KPH in Tall Grass, as long as the Cheetah was visible, the Focus in AI Servo Locked on and stayed locked on, but if the Animal completely disappeared momentarily behind Tall Grass or Bushes, the Focus was lost and I needed to re acquire focus.
On a side by side with the 300f/2.8 & 400f/2.8 I would still give the Sharpness factor to the Primes, but you need to Pixel Peep to see it, great Lens that I'm really Happy with, hope you enjoy it as much.