300mm f/4 IS+Canon EF 1.4X III extender OR 100-400 f/4.5-5.6 IS

I've been wanting to buy an L lens for a long time now. After doing a bit of research, I have narrowed it down to one of the following:
1) A Canon 300mm f/4 IS+ Canon EF 1.4X III extender
or
2) Canon 100-400 f/4.5-5.6 IS

My requirement for this is primarily for the following:
1) wildlife (zoo mostly + some safari/birding watch)
2) portrait headshots
3) random local insects,creatures.

Is there any way I can choose one over the other?
In terms of budget, both these combinations just fit into it.
If anyone owns or has used both, I would appreciate specific personal feedback rather than generic ones.

Kindly suggest.
thanks!!

oft-asked question. IQ is better @ 400mm with the zoom. owned both as well as the 300L f2.8 but i prefer the zoom to either of the 300mm + TC combos.

As your stated uses are varied the zoom is the way to go. It's really that simple Enjoy it, DON'T put a filter on it, it HATES them............

thanks guys! the zoom it is, then!

i have had the 70-200 w/ a 2X and a 100-400. The 100-400 is much lighter, faster, easier to equip and produces very similar IQ at 400. I would expect the same with the 300 and 1.4X

I shoot with numerous photogs who use the 100-400. My 300 and 1.4X II delivers sharper results almost always on the same subjects. I also found IQ the Canon 1.4x II to be superior to the Kenko DG 300, too.

Normally, I'd be all over suggesting the zoom; however, due to your stated, third requirement I'd lean toward the 300, in this case. The 300 has a much better MFD than the 100-400 does (about a foot shorter) and the extra stop would be nice for requirements two and three, as well.

If you go check out the bird forums for some examples, Levina does some fantastic work with the 300.

another important factoid about the 300 f4 that you can't forget... f4 is a full stop faster than f5.6.

so while you may be giving up some zoom, you'll be able to make shots with the 300 f4 that you simply couldn't make with the 100-400 if light isn't optimal.

drzenitram wrote in post #15604275
another important factoid about the 300 f4 that you can't forget... f4 is a full stop faster than f5.6.

actually the 100-400 is f4.5 - f5.0 at lower focal lengths
I prefer the zoom, much more versatile

When I first wanted 400 mm I considered many options and here is what happened.

I started out getting the 300 mm f/4L IS and a 1,4x extender. Used that combination very few times. Sold the lens now. (now I actually got the 300 2.8L IS MK II and have used that with a 2x extender with great results)

Got a 400 mm f5.6L as it is much sharper. Still have it and use it when I have good support.

Got a 100-400 mm. Use it a lot when I need the flexibility of zoom for example on travel.

watt100 wrote in post #15604844
actually the 100-400 is f4.5 - f5.0 at lower focal lengths
I prefer the zoom, much more versatile

Actually, the 100-400 is f/5.6 from 260mm on, and doesn't even do f/4 at any focal length.
drzenitram made a valid point.

1Tanker wrote in post #15604917
Actually, the 100-400 is f/5.6 from 260mm on, and doesn't even do f/4 at any focal length.
drzenitram made a valid point.

actually the 100-400 can do f4.5 - that is (was) the valid point


XSi (450D)
100-400
f4.5

This is the argument that was swaying me towards the 300mm. sigh.
I believe its going to come down to sharpness vs zoom and which I would rather prefer.

Mike55 wrote in post #15603971
I shoot with numerous photogs who use the 100-400. My 300 and 1.4X II delivers sharper results almost always on the same subjects. I also found IQ the Canon 1.4x II to be superior to the Kenko DG 300, too.

The difference in sharpness is marginal when you get right down to it; assuming proper holding techniques and ignoring copy variation, which probably makes more of a difference than the lens model.

I go back to your desire to be able to do flowers, etc, though. I find it tough to work with the 'pump' at the distances it normally takes to get a good angle on them; as you have to be back nearly 6ft from them. The 300 gives you a bit easier time, with its MFD being around 5ft. It isn't a huge difference, but it's noticeable.

Snydremark wrote in post #15605435
The difference in sharpness is marginal when you get right down to it; assuming proper holding techniques and ignoring copy variation, which probably makes more of a difference than the lens model.

I go back to your desire to be able to do flowers, etc, though. I find it tough to work with the 'pump' at the distances it normally takes to get a good angle on them; as you have to be back nearly 6ft from them. The 300 gives you a bit easier time, with its MFD being around 5ft. It isn't a huge difference, but it's noticeable.

Yeah.. i went through this too.. i was soooo close to buying the 100-400, but went for the 300/4L IS. I already had a 1.4x and 2x TC, so i could get my 400mm (420) with AF and IS, and 600.. for the odd occasion. The MFD, faster aperture, lower weight, sealed, non-extending lens.. plus built-in hood..all won me over.

I still have days where i consider the 100-400, but i have the 70-200/4L IS(and TCs if i want) for times when i need/want versatility. I had come from the Bigmos, which (for me), was a disappointment..and was usually at the long end with it anyways.