Canon 1.4 or 2.0 Tele-extenders

I'm getting the 70-200 f2.8 IS lens later this week. And I am tentatively planning to purchase one of the Canon tele-extenders.
I've read most (!!) of the posts I could find on this lens and some about the extenders (including the "sticky" on page 1). But I am wondering, specifically, about the optical quality of each extender with this lens.
I have read that they are both "sharp," but I am wondering about practical experience. For example, would the 2.0 version and the 70-200 effectively reduce my need for the 400 prime...which I would only use occasionally? Or would the IQ be noticeably lower with the extender. Same question with regard to the 1.4.
Thanks much.

I have that lens and don't even put the 2x in the bag anymore...ya, it's that bad!

Don't use the 2x buy the 1.4 and if you have to stack a pair of 1.4s. I have the Sigma, Tamron, Canon and the Kenko 1.4s and think the Kenko is as close to the Canon as you are going to get plus the Kenko will fit your other lens. Look at the applications that the Canon will fit before you buy it.
Just my opinion and I will probably be debated for it but what the heck.

I use a 40d and I have the 1.4x and a 70-200f 2.8 I don't so much need the IS with the lens alone but between it becoming a stop slower and 1.4x longer with the converter you will be glad to have it on that lens. It gives me just enough reach at the ballpark to not have to drag out the big guns. (anything over the size of the 70-200 probably wouldn't get past security at my local ballpark.) So for me it was better than buying a completely different lens as noe when i need it sharp for portraits I just remove the TC, when I need length I toss on the TC and still get better shots than my cousin with a 75-300.(I can get three shots before he finishes focusing.)

I would not recommend using the TC2 with a 70-200. The TC2 is primarily intended for the super teles... 200 f/2, 300 f/2.8, 400 f/2.8, etc. I think that you lose a lot when using that TC on lesser lenses.

I can't speak for the Canon TC's but have tried a 2X kenko pro on my 70-200 2.8 IS and thought it had pretty good image quality. The auto focus also worked. I did a little test w/ TC vs. cropping a pic to get the same size and could tell there was a slight difference. In all I thought the 2x TC worked good enough for my needs.

I bought the 2x TC for my 70-200mm f/2.8L IS originally, so I wouldn't have to fork out coin for the 100-400mm and carry yet another lens... I got good, usable results - but not what I'd want to use regularly. I ended up getting the 100-400mm after all. The 1.4x is a little better with less of a hit to aperture, AF speed and IQ but may not offer enough extra reach to be worthwhile, especially for the money.

The TCs sound good on paper but rarely result in great results short of using one of the "big white" lenses, which are all made to work together.

I posted a few quick samples in this thread which may be useful, but they're not with the 7-2 IS L 2.8.

My prior experience of all kinds of lenses and TCons is the high quality primes can carry them best. The zooms less so. Only zooms I have been happy with are the 70-200mm IS L 4.0 and Sigma 100-300mm 4.0 EX HSM, both amongst the best zooms you can buy and 'prime quality'.

Double Negative wrote in post #5652224
The TCs sound good on paper but rarely result in great results short of using one of the "big white" lenses, which are all made to work together.

Funny you think that - I think you'll find that the Canon Extenders and the TS-E lenses, the 135/2L, and the 70-200's are all made to work together, at least Canon seem to be under the impression that they are.
Of course you may not like the results as being below your exacting standards but they do fit and work - quite well in all cases, better than many people seem to think (perhaps these people don't own these combinations or don't use them because other people say they aren't worth using!).

PaulB wrote in post #5652346
Funny you think that - I think you'll find that the Canon Extenders and the TS-E lenses, the 135/2L, and the 70-200's are all made to work together, at least Canon seem to be under the impression that they are.
Of course you may not like the results as being below your exacting standards but they do fit and work - quite well in all cases, better than many people seem to think (perhaps these people don't own these combinations or don't use them because other people say they aren't worth using!).

Oh, they'll definitely work with lenses such as the 135mm or 70-200mm. It's on the "big whites" that they really shine, though - and what I meant by "made to work together." For example, on the 300mm f/2.8L IS you can use the TCs without a second thought (almost).

As mentioned, I got perfectly usable results using the 70-200mm and 2x TC combo. It's just a matter of what your quality standards/expectations are. And not all combos are great; while you can use a 2x on the 100-400mm you might not want to... Not only does the IQ and aperture suffer but you're also going to have to manually focus even on a 1Dxx.

I often defend the TCs on "lesser" lenses as I find they'll do well in practice. Perhaps not great, but definitely usable. But given the choice between a 70-200mm with 2x TC and a 100-400mm, I'd choose the 100-400mm however. Nothing beats native focal length. There's also a difference between using TCs on primes vs. zooms.

Get the 1.4. IQ is better and your AF and IS both function perfectly.

sml wrote in post #5651201
I'm getting the 70-200 f2.8 IS lens later this week. And I am tentatively planning to purchase one of the Canon tele-extenders.
I've read most (!!) of the posts I could find on this lens and some about the extenders (including the "sticky" on page 1). But I am wondering, specifically, about the optical quality of each extender with this lens.
I have read that they are both "sharp," but I am wondering about practical experience. For example, would the 2.0 version and the 70-200 effectively reduce my need for the 400 prime...which I would only use occasionally? Or would the IQ be noticeably lower with the extender. Same question with regard to the 1.4.
Thanks much.

I just bought the Kenko 2X for my canon 70-300mm. I Like it as long as yu use a tripod. You need alot of light.

I wouldn't even consider buying a Canon TC for a number of reasons..

1. Canon TCs will not work with all lenses including Canon
2. Are too damn expensive..

I've got a Tamron SP AF 1.4X TC (white model) which works with all my lenses including Canon..The Tamron has 8 pins or electrical contacts which preserves all lens' functions..Image quality is as good as any Canon but about 1/2 the price..