the Canon Extender EF 1,4x III is used as a teleconverter with 1.4 times focal length extension.
This extends the focal length of the EF 100-400mm to 140 - 560mm focal length and expands the Sigma 150-600mm to 210-840mm focal length. The third generation of converters is used without any
noticeable loss of quality and only a small influence on the AF speed of Canon lenses.
The luminous intensity is reduced to f4.0 for lenses with f2.8, reduced to f5.6 for f4 lenses and f8.0 for f5.6 lenses