1.4 Extender III Canon

Compared with the 2x extender 1.4x is still flexible with regard to the lens selection.
Even I use the 1.4x with the 180mm Macro (only on full-frame, the crop without), 300mm 1: 4L IS, 100-400mm 4.5-5.6 & 400mm 5.6
400mm 2.8 IS.
(100-400mm 4.5-5.6 + 400mm 5.6 to 5D Mark2 & 1D Mark III only central AF Auto Focus. Possible)
The 1.4 lossless in principle at the appropriate lens.

Here the selection of compatible lenses with each Extender.

EF 135mm 1: 2L Extender ..... 1.4 + 2
EF 180mm 1: 3.5 ............. 1.4 -
EF 200mm 1: 2.8L II ......... 1.4 + 2
EF 300mm 1: 2.8L IS ......... 1.4 + 2
EF 300mm 1: 4L IS ........... 1.4 -
EF 400mm 1: 2.8L IS ......... 1.4 + 2
EF 400mm 1: 4 DO IS ......... 1.4 -
EF 400mm 1: 5,6L ............ - -
EF 500mm 1: 4L IS ........... 1.4 -
EF 600mm 1: 4L IS ........... 1.4 -
EF 70-200mm 1: 2.8L IS ...... 1.4 2 +
EF 70-200mm 1: 2.8 L ......... 1.4 + 2
EF 70-200mm 1: 4L IS ........ 1.4 -
EF 70-200mm 1: 4 L ........... 1.4 -
EF 100-400mm 1: 4.5-5.6L IS .. - -

For some lenses, in which no compatibility is given, with the cameras of the series 1D, 1DS, the 5D autom.Scharfstellung possible with the central AF point!

The Extenderkompatibilität can be read on the Canon website in the respective description of the objective, and technical data.