The previous post covers a lot of good ground. I think your tripod may be a little light for that lens/camera combination I think that Gitzo recommends their series 3 tripods up to 400mm. I've used a 600mm/D3s on a Gitzo series 3. It can work, but if things are a little unsteady or if the wind is blowing much, things can get a bit soft. I'm unfamiliar with the head you're using. I've used mine with a Wimberley II, which works ok.