EF 2X iii extender compatibility with canon ef 70-200mm f/4l is usm

[avarela123]

Hello,

My camera is the 6D with the latest firmware installed.  I purchased the mark iii version of the 2x extender because the literature for it specifically states that it is compatibe with my ef70-200mm f/4L IS USM lens.  There are certain lenses indicated in the literature with a "*" that indicate the referenced lens/2x combo may present autofocus issues.  I confirmed that my lens is not one of those.  

My issue is that I cannot get the autofocus to work in regular mode.  The camera will not even engage the lens to hunt, even at f/8.  If i put the camera into live view, however, the auto focus will work (although not ideal)..  I previously had a mark ii copy of this 2x extender that also focused in live view but not in regular mode.  The literature for the mark ii copy of the 2x extender did not list my lens, so I sold it and purchased the mark iii specifically because it indicated that my combo was supported.  It appears that I wasted my money upgrading the extender from ii to iii.  

Is this perhaps an issue with my camera, 6d mark i, not supporting this combo in regular mode.  

Thank you very much! 

Tony

[deebatman316 · Accepted solution]

If you have the original EOS 6D it WILL NOT AF at F/8 during viewfinder shooting. The 6D Mark II can AF at F/8 though. 

[deebatman316 · Accepted solution]

If you have the original EOS 6D it WILL NOT AF at F/8 during viewfinder shooting. The 6D Mark II can AF at F/8 though. 

[avarela123]

Thanks for the fast reply and information.  It's still odd that the 6d mark 1 will auto focus that combo in 'live view' though.  I guess I will have full functionality when I upgrade my camera in the future so I will keep this equipment.

[Tronhard · Accepted solution]

Live view works because it uses the sensor to do the focusing, whereas when using the VF, the focusing is done by a separate, smaller, set of sensors around the lens mount.

[avarela123]

Makes perfect sense now. Thank you Sir!