Canon 1.4x EF Extender III with Canon 7D - Does AF Work with 70-200 f4 IS?

Started Feb 1, 2013 | Discussions thread
ScottD1964
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Re: Canon 1.4x EF Extender III with Canon 7D - Does AF Work with 70-200 f4 IS?
In reply to bhollis, Feb 4, 2013

bhollis wrote:

Mike717 wrote:

I have Canon 7D and Canon EF 70-200mm f/4 L IS USM lens. I'm looking to add a Canon 1.4x EF Extender III (Teleconverter) USA.

I've read the AF doesn't work with the 7D combo. Is this true?

Thanks,

Mike

No, it's not true The 1.4x TC results in the loss of one stop, which will give you a max aperture of f/5.6, and the 7D is capable of autofocusing at f/5.6. IQ will be slightly degraded, and autofocus will be noticeably slower, but it will work.

Actually only the Canon 1.4x tells the camera AF protocol to slow down the focus speed (25%). If you use a 1.4x TC like the Kenko Pro 300 1.4x DG or DGX, while it does report all correct exposure data, it does not slow the focus speed the way the Canon is designed to.

I've used the Kenko on both my 7D and T1i (70-200 f4 L IS and 70-200 f2.8 L) with pretty much no loss of IQ at all and the Kenko is 1/2 the price of the Canon.

Here are a few samples.  All straight OOC .jpegs no post processing.

Not sure why the images rotate 90 degrees when posted from gallery.

Scott



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