Canon Extender EF 1.4x III review: extend your telephoto reach, not your budget

The Canon Extender EF 1.4x III offers a cost-effective way of boosting the focal length of compatible telephoto lenses.

Canon Extender EF 1.4x III
(Image: © Matthew Richards)

Digital Camera World Verdict

Small, lightweight, and convenient, I like that the Canon Extender EF 1.4x III gives a 1.4x extension to compatible telephoto lenses. Build quality and performance are impressive, making it a cost-effective option.


  • +

    1.4x telephoto boost

  • +

    Compact and lightweight

  • +

    Good quality build and performance


  • -

    1 f/stop drop in aperture

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    Slight impact on image quality

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    Not compatible with all lenses

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The Mark III edition of this Canon 1.4x Extender, or teleconverter, is the latest (and probably last) in the EF-mount series, designed for Canon cameras and compatible EF-mount Canon telephoto lenses. It’s primarily designed for DSLRs but can also be used on EOS R-system mirrorless cameras via an EF-EOS R mount adapter

As such, it’s one of the best teleconverters on the market. As a 1.4x teleconverter, the focal length of the attached lens is magnified by a factor of 1.4x, with a 1 f/stop reduction in aperture rating, so a Canon EF 70-200mm f/2.8L IS III USM zoom effectively becomes roughly a 100-280mm f/4 lens.

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MountCanon EF
Lens construction7 elements in 3 groups
Focal length multiplier1.4x that of main lens
Aperture reduction1 f/stop
Minimum focus distanceSame as main lens
Maximum magnification1.4x that of main lens
Filter sizeN/A
Dimensions72 x 27.2mm
Canon Extender EF 2x III gives 2x

The Canon Extender EF 2x III gives 2x magnification rather than 1.4x, so it’s more powerful but bigger and heavier, and you lose two f/stops in aperture instead of just one stop.

Canon Extender RF 1.4x

If you use an EOS R-system camera, the Canon Extender RF 1.4x is the native equivalent for mirrorless camera bodies and compatible RF-mount telephoto lenses.

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Matthew Richards

Matthew Richards is a photographer and journalist who has spent years using and reviewing all manner of photo gear. He is Digital Camera World's principal lens reviewer – and has tested more primes and zooms than most people have had hot dinners! 

His expertise with equipment doesn’t end there, though. He is also an encyclopedia  when it comes to all manner of cameras, camera holsters and bags, flashguns, tripods and heads, printers, papers and inks, and just about anything imaging-related. 

In an earlier life he was a broadcast engineer at the BBC, as well as a former editor of PC Guide.