Good wildlife companion for the 300 2.8

I have 2 30D bodies and I'm about to get a 300 2.8 which I intend to use a lot of the time with extenders. I'm thinking about getting another long lens to use on the 2nd body, I already have the 70-200 2.8 but was also thinking of maybe getting the 400 5.6 as I love to capture birds in flight, or maybe a 100-400? The only thing stopping me getting the 400 5.6 is the thought that Canon may bring out an IS version in the near future?

Your thoughts please. My budget is around the 400/100-400 price range.

Sounds like you have a great plan already. Sounds like you want the 400, but are hesitant because Canon might release the IS version. I say get the 400 now and learn to use it without IS. If Canon does release a IS version and you feel you want it, sell the 400, it will fetch about $900.00 used. Plus, birds in flight require high shutter speeds which would negate IS anyways

Paul, it's a tough one.
Big prime and zoom Vs. Big prime and another prime.

I'd say it's definitely one or the other (400mm 5.6 or 100-400)

But which is really tricky.
So far I am living with the 100-400mm on my second body. I like the zoom, and the IS and the very close focus.

I dream of the 400mm f/5.6 however with it's superb optics and ULTRA-Fast AF...

Can we carry all three?

With the 300 2.8 you will have 300mm, 420mm and 600 mm covered with extenders so you will not need the 100-400mm. It would be overlap. Use the 70-200 2.8 you already have. The 400 5.6 for birding on a 2nd camera set up for birds in flight would be the only thing that makes any sense. The 100-400's slower af is not as ideal for birds in flight.

a say 400 5.6 sounds like a great plan. and you dont need IS for birds in flight.

I rented a 300 f/2.8 a couple of months ago, and I took it out with a 1.4TC on my 5D and the 100-400 L on the 20D and it worked out great. The zoom really helps when you want to shoot some closer subjects quickly.

Personally I would avoid a 400mm f5.6 at all costs. Because a 300mm f4 with 1.4xTC is a much better combo. And you can use the 1.4x on other white lenses. Basically this option gives you the option of a 300mm lens or a 420mm lens. Just an idea.

Yes that combo gives you 300 or 420mm but it is not a good option IMHO as the 300 f4 + TC is going to be inferior from both an AF and an optical point of view to the bare 400 f5.6 prime.

At the moment I'm tending to lean towards getting the 100-400. I do quite a lot of travelling and I think having the 100-400 in my bag for such times that the 300 2.8 has to be left at home would be more benificial than say having the 400 5.6. I think the 100-400 would just get more use than the 400 5.6. The IS is a big plus of course!

Not even close. Using a 20D I do not find any difference in focus speed or loss of sharpness with my 300mm f4 and 1.4x TC. Besides the 400mm f5.6 lens looks like its the 300mm lens with the TC on it.

Can't say optically speaking but there must be a reason why more people seem to buy the 300 f4 rather then the 400mm f5.6. 300mm lens? The 300mm is the sharpest lens I have ever used.

i used to say the exact same thing about the 300 vs 400. but for birding the extra AF speed of the 400 is definitly (ive used both) there and helpful. Also, IS is a great feature, and i wouldnt mind having it at times, but for action shots, it just plain isnt going to do anything but add weight to the lens. I dont mean to down anyone useing the 300 w/ 1.4x combo, if its working great for you congrats. But it just seems more sensible for him to get the 400 5.6 for flying birds (which is what it was basically born to do, and what it is master of) since he already has the 300 2.8.

Go for the 100-400 mate,when you get that 300f2.8 and 1.4 you have a faster 420 f4 and I find it does not alter IQ or focusing speed.

Up until about an hour a go I'd had a change of heart and decided to go with the 400 5.6, now I'm back with the 100-400

if it is for flying birds go with the 400 5.6. cant be beat.

if its for versitility than go for the 100-400. but at the same time if stuff get close enough for you to need under 300 u can use the 70-200.

Ok I've made a decision....drum role....the 400 5.6 it is

Thanks everybody for your input.