Canon Extender EF

These lenses are used between any compatible EF type lens and any of the Canon EOS line of cameras.

Canon has released six models: The extenders are constructed with metal bayonets, and engineered plastic ends.

The II versions have weather-sealing and anti-reflective surfaces inside the extender body.

Image stabilization may not work on lenses that are equipped with an extender, or on certain EOS bodies.

[5] With a 2× extender a 400mm f/4 lens would have an equivalent focal length of 800mm and a maximum aperture of f/8, in which case autofocus would only be available with professional bodies.

[9] Canon EOS bodies that have Dual Pixel CMOS AF like the 70D and later models support autofocusing in Liveview mode, with maximum apertures as small as f/11.