Used Canon EF Extender 1.4x III

Condition & contents

At a glance: EF 1.4x III teleconverter - extends compatible L-series telephotos by 1.4x, weather-sealed, 1-stop loss.

About this lens

The Canon EF Extender 1.4x III is Canon's professional-grade 1.4x teleconverter, released in 2010. Multiplies the focal length of compatible L-series lenses by 1.4x with one stop of aperture loss. Weather-sealed and optimised for modern super-telephoto L-series optics.

Build & handling

Works with

• Canon L-series telephoto lenses only (see Canon compatibility chart)
• Works on Canon EF-mount full-frame and APS-C DSLRs
• Works on Canon RF mirrorless bodies via EF-EOS R adapter (stacked with the converter)

Best for

A pro-grade teleconverter for extending the reach of compatible Canon L-series telephoto lenses - typically the 70-200mm f/2.8L, 300mm f/2.8L and 400mm f/2.8L-class primes. Adds roughly 40% more focal length at the cost of one stop of aperture. Not all Canon EF lenses are compatible - check Canon's compatibility chart before purchase.

Frequently asked questions

Which lenses is this compatible with?

Only specific Canon L-series telephoto lenses - primarily the 70-200mm f/2.8L IS, 300mm f/2.8L IS, 400mm f/2.8L IS, 500mm f/4L IS, 600mm f/4L IS, and 800mm f/5.6L IS families. It will not fit or function correctly with shorter L-series lenses, non-L lenses, or EF-S lenses.

What's the difference between the Mk II and Mk III?

The Mk III (2010) adds weather-sealing, improved optical coatings, and re-optimised correction for current-generation L-series telephotos. The Mk II remains optically capable on older lenses.

Will it work on Canon RF mirrorless bodies?

Yes, via the Canon EF-EOS R adapter. Autofocus and IS are preserved, and the lens functions normally on R, R5, R6, R7, R8, R50 and other RF bodies.