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Canon Extenders II vs III

Started Jun 13, 2011 | Discussions thread
Dan_168 Forum Pro • Posts: 11,055
Re: Improved AF performance

40d_dane wrote:

According to the newest CPN newsletter, the mk III extenders does improve AF speed on earlier EF lenses:

http://cpn.canon-europe.com/content/education/technical/latest_ef_lens.do

This is in contradiction to what Canon has previously claimed (only AF improvements on the mk II lenses). I do have AF issues when I use my 1.4x mk I extender on my 500mm + 7D (probably AF speed issues, optically the combination is hard to fault), so I am seriously considering getting a 1.4x mk III to check it out.

Interesting, when we tested the 2X TC III against the TC II on the 70-200 F2.8 IS II and the 300mm F2.8 IS MK1 last month we thought we did notice a slight improvement on AF speed, but just based on the press release info we read back then claiming the benefit can only be seen on the new MK2 primes and didn't mention Mk2 zooms, so we all thought it was just our imagination or something, but now they said even the old lens and zooms can be benefited from it, hummm, which one should we believe them?? but since I am getting the new MK2 prime soon so it makes sense for me to upgrade to TC III anyway. and I think the new coating on the TC III will help to improve the IQ on the old lens even we don't get the improvement on AF speed, so it's still a good thing to have.

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