[koputai (Jason)]

Hi Folks,

I'm wanting to get a new tele lens for an imminent safari trip to Botswana, Zambia, and maybe Tanzania.
At the moment I have a 350D (50D or 7D coming soon) so am using a 1.6x crop body.

I also have a 70-200 f/4L IS, which I love and am not planning to get rid of. I currently have a 1.4x extender which takes this lens to 280mm, but I really don't like using the extender.

So I need a bit more reach for animal/bird shots etc.
I'm tossing up between the following:

300mm f/4L IS - Lovely lens, moderate increase in focal length from what I have. Maybe not enough difference to justify.

400mm f/5.6L - Good increase in focal length, a bit slower, and no IS.

70-300mm f/4-5.6L IS - The new wonder lens. Probably too close to what I already have.

100-400mm f/4.5-5.6L IS - Very versatile focal length, older IS, push-pull zoom.

I'm leaning towards the 400mm or the 100-400mm. All these lenses are similar in price, so that's not an issue.

Anyone into nature photography have any opinions on which way I should go? I'm open to suggestions.

Cheers,
Jason.