Canon Extender EF 2.0X Mk III

Designed to complement the Canon EF300mm f/2.8L IS II USM and the EF400mm f/2.8L IS II USM telephoto lenses, these Mark III Extenders will increase the focal length of these lenses while maintaining very high image quality. Although designed and launched to work well with the two telephoto lenses named above, the Extenders will also function with all other Extender compatible Canon EF lenses.

To ensure lens optical performance and autofocus performance remains high, both extenders feature an integrated processor to transfer all focus and lens information back to the camera. To ensure this is working optimally, you should always attach the lens to the extender before attaching the extender to the camera body. This will ensure the combination lens information is transmitted correctly and completely. Compared to the Mark II Extenders, these new Mark III Extenders will offer increased AF performance with all EF lenses.

The extenders are compatible with any L-series lens with a focal length of 135mm or longer, as well as the following zoom lenses: the EF70-200mm f/2.8L IS II USM; EF70-200mm f/2.8L IS USM; EF70-200mm f/2.8L USM; EF70-200mm f/4L IS USM; and the EF70-200mm f/4L USM.

For wildlife and sports photographers these extenders can prove invaluable accessories – the lion that is too small in the frame with the EF400mm f/2.L IS II USM lens gains much more impact when the EF1.4x III is used to give a 560mm f/4 lens. Using the EF1.4x III will cause a loss of one stop of light, so a lens with an f/2.8 maximum aperture will become an f/4 maximum aperture. The EF2x III Extender causes a loss of two stops of light, so an f/2.8 lens becomes an f/5.6 lens.

Both of the extenders feature dust and moisture resistance, so when they're used with their compatible lenses you can continue shooting in severe conditions. The join between the extender and lens and camera body has also been made tighter. This makes the unit feel more firmly attached and helps to minimise dust and water ingress. The lens mount also features more screws to provide a more robust mounting point.

The design has been modified to fit the look of the EF300mm f/2.8L IS II USM and EF400mm f/2.8L IS II USM lenses and the lens release switch has been changed to allow quicker attachment and release of the extenders. This is especially useful in harsh environments where minimising the time that the lens is off the camera helps to keep dust and moisture out of the camera body.

If the lens features an Image Stabilizer this will continue to function when the extenders are fitted. Similarly, with an EOS-1 series camera, autofocus will continue to function on all lenses when using the EF1.4x III extender. Using the EF2x III extender will cause autofocus to stop working if the maximum aperture falls below f/8. With non-EOS-1 series cameras this limit is reduced to f/5.6.