400 prime on 6d body not working when attached to Kenko c-AF 2x teleplus mc4. Why?

[Lucashots]

See subject. Works on all other ef lenses in bag? I get total shutdown of camera, no windows, functions at all

[ebiggs1]

No it won't work on the 6D. I don't believe but since I don't have a 6D maybe someone else has an idea.  You can try to tape the pins on the converter and that might let it work.

2X tele converters are a poor idea in the first place.  IMHO, of course.

[Lucashots]

Thank you!

[diverhank]

I'm not familiar with the Kenko 2X but if it reports the settings to the camera, the camera won't allow it because the 400mm f/5.6 (i assume this is the one you have?) with the 2X will have the minimum aperture of f/11.  The 6D cannot autofocus beyond f/5.6 so this is possibly why it won't work.

As Ebiggs said, you can try taping the pins (google for procedure) to fool the camera in thinking it's still f/5.6.  I also recommend against using the 2X on such a lens...the result will not be optimum in both Autofocus and image quality.