Originally Posted by
William W
Definitively better using the EF Extender 1.4 MkIII with the EF 70 to 200 F/2.8 L IS MkII USM. For that lens alone I suggest that you buy the Canon Extender EF MkIII.
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I use a 70 to 200/2.8 + Extenders EF often: I have tried all combinations of the three (3) 70 to 200/2.8 lenses and the four (4) Extenders EF MkII and MkIII.
I have not used the MkII version of the 100 to 400 lens: I have used the 100 to 400 (original) with the EF Extender MkII versions - not the MkIII - but it is logical, that the MkIII extender would not be a retrograde step using it on the 100 to 400MkII. You might want to tape the contacts using this lens - do you know what I mean? - if not I have a picture of it, let me know.
I understand that no Canon Extender EF is compatible with the 70 to 300L. As I understand some might mount and some might not mount, and the ones that do mount will crash into the rear optic during zooming, thus only facilitating use at a reduced zoom compass.
WW