Canon RF 400mm f/2.8L IS USM review: if it ain’t broke, don’t fix it

The ‘new’ Canon RF 400mm F2.8L IS USM isn’t really new. It’s more a tweaked EF-mount lens for mirrorless EOS R-series cameras

5 Star Rating
Canon RF 400mm F2.8L IS USM
(Image: © Matthew Richards)

Digital Camera World Verdict

The Canon RF 400mm F2.8L IS USM is a spectacular lens for action, sports and wildlife photography. It’s super-pricey but you get what you pay for and I love the combination of super-telephoto focal length and fast f/2.8 aperture, with sublime performance and image quality.


  • +

    Long reach, fast aperture

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    Super-fast autofocus

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    5.5-stop optical stabilization


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    Not much is new

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    Necessarily big and heavy

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    Very expensive to buy

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Canon’s big white telephoto lenses are widely respected for their quality and performance, I can’t argue with many of the world’s most demanding professional sports and wildlife photographers. The EF-mount range includes some of the best Canon lenses for DSLRs, while the growing range of RF-mount options widens the remit for the best Canon telephoto lenses for both DSLRs and EOS R-series mirrorless cameras.

The RF 400mm F2.8L IS USM is the fastest of Canon’s big guns, coupling a generous super-telephoto focal length with a fast f/2.8 aperture. This gives the double bonus of delivering a tight depth of field when you want it, and fast shutter speeds for freezing movement when you need to, even under dull lighting conditions. But we’ve been here before, as I’ll come to next.

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Mount optionsCanon RF
Lens construction17 elements in 13 groups
Angle of view6.2 degrees
Diaphragm blades9
Minimum aperturef/32
Minimum focus distance2.5m
Maximum magnification0.17x
Filter size52mm drop-in
Dimensions163 x 367mm
Canon RF 100-300mm F2.8L IS USM

If you demand an f/2.8 aperture but would prefer the versatility of a zoom lens, albeit with less outright telephoto reach, the Canon RF 100-300mm F2.8L IS USM is a similarly spectacular lens.

Canon RF 100-500mm F4.5-7.1L IS USM

If you don’t need such a fast aperture, the versatile Canon RF 100-500mm F4.5-7.1L IS USM zoom lens gives even greater reach in a much more compact, lightweight, and relatively affordable package.

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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.