400mm f/5.6 or 300mm f/4 + Ex1.4?

Happy new year everyone!
I'm thinking about next tele lens, I have 2 options:
- Canon 400mm L f/5.6
- Canon 300mm L IS f/4.0 with Extender 1.4x (420mm L IS f/5.6)
But the second option I will lose focus speed but get 420mm with IS. I use tele lens for the birds.
Any cc are appreciated. Thank all!

I had the 300/4 + 1.4XTC for a while and liked very much. However, once I try the 400/5.6, I decided to keep only the 400/5.6. I do mostly birds (in flying), and the 400/5.6 is really the best of the two. On my 7D is a real winner.

400mm for birds! I want one too but waiting for my tax refund..

400 5.6 for sure.
fast AF is a necessity with birds.
Sometimes you only have a second or 2.

If you need to leave the TC on all the time to achieve your desired focal length, you are better off getting the 400 f/5.6. Why hamper your AF performance and image quality?

To be honest, I would go with the 300 + 1.4 if I bought back into the super telephoto again. Had both and I much prefer the excellent MFD and IS on the 300. But I also shot much than just birds with mine. For birds only, the 400 will be better with AF speed and IQ.

FYI, adding the 1.4X to the 300/4 causes virtually no slowing of AF. If you can tell any difference in the field, especially using the lenses on a 1D series camera, I'd be impressed. Personally I've used the combo mostly on 50D, 7D and more rarely on 5DII (it's a sports/action/wildlife lens combo, and the 5DII simply isn't a great choice for that type of shooting). I don't notice any perceptible change in AF performance on 7D.

I have not extensively compared the 400/5.6 (only used it a little, never owned one), so can't compare AF speed... But the 300/4 is nearly instantaneous under all but the worst lighting conditions.... So I can't imagine much better. The 300/4 isn't noticeably slower focusing than 300/2.8 IS and is probably a smidgen faster than 500/4 IS, both of which I do own and have used for years, so can compare.

The nice thing about the 300 + 1.4X is you have two focal lengths to work with, rather than just the longer one. Plus you get IS, so it's a bit more handholdable.

shooting birds, 400mm f5.6 All the way. not sure why MFD is an issue unless you shooting albatross on galapagos where they will probably sit in your lap.

I shot birds for couple of years with 100-400, 400mm f5.6 and 500mm f4 and only once the bird landed close where i couldnt focus with 400mm f5.6. 500mm was mainly used at 700mm like any other bird photographer.

A friend took a 100-400 zoom to an African safari, when we reviewed the photos, most of them were shot at 400mm FL.

Alan, with all due respect, I have 300mm f2.8 IS and with 1.4xTC, AF slows down. This on 1dmk2. 400mm f5.6 bare is faster to AF for birds in flight then 300mm f2.8 IS with 1.4xTC. And we all know 300mm f2.8 IS is much better than 300mm f4 IS. And 400mm f5.6 is super sharp at f5.6 compared to 300mm f4 IS with 1.4xTC.

It is curious, this dilemma is one that most of us face at one point. I had the chance to try both, and decided for the 400/5.6. The main reason is: IS will help the hand shake, but not the object movement. If you want to capture the moving subject, you have to increase the shutter speed enough to capture it (1/2000s for hummingbird wings, 1/125s for walking horses - if you follow the rule of 2 X the focal lenght, or 2x400= 1/800s you will be safe for most subjects. THis is one of the shots I took with my 5D II. Usually, I will only see the point at the end of the stream, however, this plane is SHARP!!! unbelievable!!

IMAGE LINK: http://www.flickr.com/​photos/palenquero/8125​677920/

a 400 f5.6 combined with a flight brace helps steady the lens

http://joenoordman.smu​gmug.com …gsdb#!i=1705431​78&k=RgPPM

Thanks for all comments
I'm using FF body (as my signature), Someone told me, I better upgrade to 1D MIII, MIV, or 5 DMIII because AF system of 1Ds MII not good enough to take the bird picture.
I know for sure Tele with TC will be slower than, but how's slow? and Is it work well with 1Ds MII

If you're shooting birds in flight, exclusively, or almost exclusively, I'd go with the 400L; if you use it for some BiF as well as other subjects, I'd go with the 300 and TC. IS is handy to have, but for those birds, I'd want all of the speed advantage I could get in order to catch 'em.

bobbyz wrote in post #15430951
Alan, with all due respect, I have 300mm f2.8 IS and with 1.4xTC, AF slows down. This on 1dmk2. 400mm f5.6 bare is faster to AF for birds in flight then 300mm f2.8 IS with 1.4xTC. And we all know 300mm f2.8 IS is much better than 300mm f4 IS. And 400mm f5.6 is super sharp at f5.6 compared to 300mm f4 IS with 1.4xTC.

my 100-400L is sharper at 400mm than the the 300L f2.8 IS + 1.4 TC and also focusses faster.