Canon EF Extenders are designed for use with a number of telephoto and zoom EF lenses. They do not work with EF-S or EF-M lenses. They can be used with a compatible EF lens on a Canon EOS R System camera with an EF-EOS R Mount Adapter.

Extenders are a convenient way of enhancing your telephoto capability. But using them to increase focal length comes at a cost as it reduces your maximum aperture. The 1.4x Extender causes a decrease of one stop in the maximum aperture of the lens, while the 2x Extender causes a loss of two stops. This means you gain extra focal length at the expense of losing some light. If you attach a 1.4x Extender to an EF 70-200mm f/2.8L IS III USM lens, for example, it will become in effect a 98-280mm f/4 lens. If you use the same lens with a 2x Extender, it becomes a 140-400mm f/5.6 lens. In the same way, the EF 70-200mm f/4L IS II USM lens has a maximum aperture of f/4, but with a 1.4x Extender, the effective maximum aperture becomes f/5.6, while with a 2x Extender it becomes f/8. So it entierly depends on your preferance and capabilities of your kit for the shots you require.

Focal length extension for super-telephoto lenses

The Extender EF 2x III is specially designed to work in conjunction with L-series IS super-telephoto lenses, extending their focal length by a factor of 2x. The extender’s design ensures there is no loss of lens performance or image quality.

High-quality construction

Improved anti-reflection materials inside the lens-barrel and a coating around the outer edges of the lens elements reduce flare. Construction is resistant to dust and water, helping to maintain images quality.

Improved communication between lens and camera

A built in microprocessor provides accurate transfer of data from between the lens and camera delivering an improved performance in AF and metering.

Compatible with L-Series telephoto and telephoto zoom lenses

The Extender EF 2x III is compatible with most telephoto and telephoto zoom lenses within Canon’s flagship professional L-series range, extending the focal length while only reducing the effective aperture of the lens by two stop.