Canon 1.4X III vs Canon 2.0X III

[Loswr]

Honestly, I'm getting lost when I see some people posting sharp pictures with the 2x III - 70-200 2.8 L II combo.
Please don't tell me Canon gave me a bad copy of their extender...

The combo should less sharp than the bare 70-200 II, but still quite sharp.

Example with the 5DII:

EOS 5D Mark II, EF 70-200mm f/2.8L II IS USM + EF 2x II Extender @ 260mm, 1/250 s, f/5.6, ISO 400

Example with the 7D:

EOS 7D, EF 70-200mm f/2.8L II IS USM + EF 2x II Extender @ 400mm, 1/160 s, f/5.6, ISO 3200

If your not getting sharp images, the first question I'd ask is if you've done an autofocus microadjustment. Do note that the AFMA needs to be done separately for the lens + TC combo.

 

[Skulker]

I use the 2x with the 70-200 on the 5D3 and find it very good. Although the setup is a bit on the long side when you have it on there.

I never used it much with the 7D a camera that I really liked, with any lens. I think these latest TC's really only work to their best with the latest generation of lenses and cameras. But as show by Neuro above, they can produce good results.

 

[TommyLee]

I use a Tamron sp pro 1.4x on the 70-200 II... just fine

but the 2x III is fairly good..... on that lens too

having f8 NOW, on the 5D3, also allows me to use the 2x III on my 70-200 f4 I.S. ...
but the native lenses are much better in focus speed and clarity

TOM

 

[RGF]

I have both and routinely use the 1.4 while avoid the 2x - perhaps because I put this on a 500 F4 which makes it F8 which is hard to focus. I have a mix results with the 2x, I think the problem is with the photographer, not the equipment but it is much harder to use the 2x on an F4 lens than it is to use 1.4x

I have spent much time using either TC on 2.8