Best lens for mountains (wildlife)

[Penjac]

I'm thinking a lot last days which new tele-toto lens to buy since I found my 70-200 is not enough for any serious picturing in mountains (wild animals).

And now I found big problem since there are many lenses in market around 400mm so I just can't decide what to choose, and what lens is best..

Since I have 70-200mm (+1,4TC and 2.0TC) I remove all lenses up to 300mm because I can get to that range  with 1.4x TC) and I mostly focus on 400mm+ lenses. Here is my short list of what I find that can match my needs. Just to say my camera is 20D, and soon will be 40D.

Canon EF 100-400mm f/4.5-5.6L IS USM
Sigma APO 50-500mm F4-6.3 EX DG HSM
Canon EF 400mm f/5.6L USM

I was thinking about Canon EF 300mm f4.L IS USM + 1.4 crop factor but I find that quality of picture is lower then 400mm f5.6 so I remove it from list and if I ever need more then 400 then I need to put 2.0xTC and picture quality will be probably not good.
Thnx in advanced for your help..

I'm mostly looking for lens with I can shoot from hands since I will not have time to take my monopod from backpack. and usualy I will shoot during day. Of course Image quality is important too.

[Goodlistener]

It seems like the combination of hand held and long lenses very much adds up to an image stabilized model - which leads to Canon.  BTW, have you posted any of your wildlife images on line at PBase or Flickr et al?

Photozone.de seems to have the most quantitatve and methodical lens reviews that I know of.

[Penjac]

It seems like the combination of hand held and long lenses very much adds up to an image stabilized model - which leads to Canon.  BTW, have you posted any of your wildlife images on line at PBase or Flickr et al?

Photozone.de seems to have the most quantitatve and methodical lens reviews that I know of.
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I didn't know about that page I will check it.

No I didn't because I only have few from this year  Last years I didn't have luck so they was very very far for my 70-200 + I have some zoom problems with camera and lens so they are now (more then month and half) on service. I hope to get them back soon fixed ofc:)

Here are pictures of my vacation this year: [a href=\"http://karadza.org/galerija/thumbnails.php?album=23]http://karadza.org/galerija/thumbnails.php?album=23[/url]

and this is from animals I take picture (with some 12x zoom sony because my backup camera stop working on vacation, while main was on service atm)

[stever]

i really recommend the 100-400 as an all-round lenst that you can carry, particularly for a crop frame camera

the 400 5.6 will be sharper, but not image-stabilized or as versatile

the 300 f4 with a 1.4 extender isn't notiecably sharper than the 100-400 (neither is that great wide open) and won't autofocus with a 2x extender.  the 100-400 with the last 3 pins taped will autofocus (slowly) with the 1.4x with acceptable results if you don't try enlarge much past 8x10

i would discount the Sigma entirely for image quality

the Tamron 200-500 at 500 is about the same as the 100-400 +1.4x but doesn't seem to have as much contrast and must be used on a sturdy tripod