300f/4 IS or 400 f/5.6 or 100-400

[Homer]

Hey Everyone,
I need some assistance trying to figure out which telephoto lens to buy next for my 20D. Seeing as these three lenses all have excellent reputations and are relatively close in price I am having a huge problem trying to figure out which lens to get. The lens would be used mostly for nature photography, birds would be the main subject.
Already owning the 1.4 TC I would lean towards the 300 f/4 over the 400 because it would give a slightly longer focal length and have IS at the same 5.6 f-stop. I can't see anyone using the 1.4 TC on the 400 as I imagine manual focusing at that focal length would be a pain. Can anyone attest to the image quality of the 300 & 1.4TC combo vs just the 400 on its own?? Would I notice any difference?
I like the versatility of teh 100-400 and the IS but I already have a 70-200 f/4 and a 1.4x TC that covers the lower end of that range. Again I wouldn't use the TC on the 100-400 because of auto-focus loss.
Can users of these lenses provide any insight??

[pturton]

You may be interested in reading the following thread from a couple of days ago.

http://photography-on-the.net/forum/showthread.php?t=75892

Paul
http://www.iaw.com/~pturton/

[tommykjensen]

And have a look here too:

http://photography-on-the.net/forum/showthread.php?t=56149

[Homer]

Tommy,
Are you pleased with your purchase of the 300 f/4? equally pleased with pictures using the 1.4 TC?

[lomond]

You'll get a lot of useful info from reading the above threads.
However, this is my 2p worth.

I have the 300 plus 1.4TC and the 100-400.
the 100-400 is versatile and I wouldn't be without it, just a tad soft at 400.

The 300 is sharp and with the 1.4 TC attached you still have AF. There must be some degradation in image quality with the TC but I'm buggered if I can see it. IS means I can shoot at relatively slow shtter speeds.

Although I don't own the 400 prime, I'm sure it will be sharper than the 300 + TC.
You will need good light to keep the shutter speed up and avoid camera shake.

All in all, for bird photography, I would suggest the 400 prime.

In fact it's on my wish list. But not for a while yet. :(

[tommykjensen]

Tommy,
Are you pleased with your purchase of the 300 f/4? equally pleased with pictures using the 1.4 TC?

Yep, very pleased.

Here is a few of my photos shot with that lens, the last one also with the extender.

http://photo.klein-jensen.dk/photohtml.php?n=zoo050306leopard1a.jpg

http://photo.klein-jensen.dk/photohtml.php?n=zoo050320lion1.jpg

http://photo.klein-jensen.dk/photohtml.php?n=zoo050306penguin1.jpg

Some day I will probably also buy the 400 f/5.6 L :D

The reason why I have not bought the 100-400 is only because after trying it I did not like the push/pull zoom. But most love that lens.

[Homer]

Tommy,
Your shots are awesome, i'd be very happy with results like that. Even with the TC, its extremely sharp