Worth it to upgrade Extender 1.4 II to a Mk III?

[RC]

Been contemplating if it's worth the upgrade, improved IQ and AF,  to upgrade to a 1.4x or 2x Mk III Extender.

With spring training (baseball) just around the corner here in AZ, I want to be ready if I choose to upgrade.  I will be using my 7D with my 70-200 2.8 II for outdoor games and once regular season starts (indoor games), I will use both my 7D and 5D3.  I'm more interested in the 1.4x but am considering the 2.x  Thanks

[Mt Spokane Photography]

Probably not a big improvement.  The 2X II to 2X III is a bigger improvement.  I'm keeping both of my version II extenders.

[TexPhoto]

I had a 1.4X V I and  2X V II. I upgraded both to V III and was very happy.  The 1.4 went from acceptable to I swear I owned a 600mm prime (well 560, when attached to my 400mm f2.8 IS)  The 2X was an improvement, but still not sharp like a bare lens, or the 1.4. 

I am thinking of selling my 2X V III, because I don't see a ton of difference in a 800mm shot, and crop from 560mm.  I keep hoping to run into someone with a VIII 2X to compare mine to.  Maybe mine is off a little.

[natureshots]

Been contemplating if it's worth the upgrade, improved IQ and AF,  to upgrade to a 1.4x or 2x Mk III Extender.

With spring training (baseball) just around the corner here in AZ, I want to be ready if I choose to upgrade.  I will be using my 7D with my 70-200 2.8 II for outdoor games and once regular season starts (indoor games), I will use both my 7D and 5D3.  I'm more interested in the 1.4x but am considering the 2.x  Thanks

Consensus is for the 1.4x you gain practically nothing by upgrading from the vII to the vIII. The only good reason for the upgrade would be if you needed better AF for a supertelephoto vII prime ($6500+). For the 2x the vIII is worth the $400 for there's marked increase in quality. Its important to realize that if you are not going to use the 280-400mm range increase from the 2x then skip it. Even with the vIII its substantial hit with the 70-200mm. You will definitely get better results with the 2x vIII than if you crop with a 1.4x though.

[AlanF]

The Mark III extenders are designed for the Mk II 300, 400, 500 and 600 lenses to optimise focussing speed and be a match for their optics. If you look at at the MTFs on the Canon USA site for those lenses with extenders you will see they are exceptional. The-digital-picture site has crops for all Canon lenses with Mk II and III extenders on and you can see some improvement in CA for the x2 in particular. The IQ of the x2 III on the II series lenses is very acceptable, by repute and by my own experience on the f/2.8 300mm II.

[Lnguyen1203]

I have upgraded from the 2X ii to 2X iii and am pleased with the upgrade.  The 2X iii gives me better sharpness, more details in the shadow when used with the 500mm f4 II (see an image here at 1000mm focal length and f11).  I have also used the 1.4X ii and will upgrade to the 1.4X iii (already placed order) to get better AF with the 500mm f4 ii.  According to Canon the teleconverter 1.4X and 2X Mark III have a chip inside that allows faster AF with the new super telephotos like the 500mm f4 II.  So, I will post some pictures when I have the 1.4X iii, but my expectation for IQ improvement is small if any and I will most likely can't tell the difference.

[neuroanatomist]

For a 70-200/2.8L IS II, I would not bother to upgrade the TC(s) to a MkIII.  If you have a MkII supertele lens, the upgrade is definitely worth it. 

[RC]

Thanks for all for the feedback!   Glad to know that I'm not missing anything with the 1.4 Mk II Extender on the 70-200 II.

Now I recall reading that the Mk IIIs were optimized mostly for the real big whites.