Soccer w/ Canon 70-200 f4LIS vs. 2.8L (w or w/o IS)

Started Mar 19, 2010 | Discussions thread
Contributing MemberPosts: 561
RE: Canon 70-200 f4LIS for sport
In reply to ScottD1964, Mar 21, 2010

Thanks Scott
Didn't realize this, need to read up more

ScottD1964 wrote:


No both the Canon and Kenko 1.4x will drop 1 stop so the f4 will be an f5.6 max aperture with the TC in use no matter which brand.

What I'm saying is the Canon firmware in the camera body automatically slows the focus speed of the given lens by 25% when it senses the Canon 1.4x being used. The Kenko does not cause the firmware to slow the lens focus speed. The lens is able to follow action at a faster AF speed (very close to the focus speed of the actual bare lens) when using the Kenko 1.4x than it would with the Canon 1.4x.

Hope that clears things up a bit.


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