The Canon RF 400mm F2.8L IS USM is not really a new lens, but the RF version of the EF 400mm F2.8L IS USM III. So it’s actually a telephoto lens with a fixed adapter.




  • Bright

  • High image and build quality

  • Fast autofocus

  • Usable with teleconverters

  • Rear filter holder

  • Price

  • No Control Ring

  • No front filters

The Canon RF 400mm F2.8L IS USM is optically exactly the same as the latest EF 400mm F2.8L IS USM.


No camera system is really complete without bright telephoto lenses for demanding sports and nature photographers. That’s why the Canon RF 400mm F2.8L IS USM is now available for the Canon R system. It’s not really a new lens. It is optically exactly the same as the EF 400mm F2.8L IS USM III. In itself, there is nothing wrong with that. That EF version is very good. The other big news from that 400mm in EF version was also the weight, which was 1010 grams less than its predecessor. And you can feel that for sure when you spend a day with this lens. The RF version is 50 grams heavier because it has an extra tube section on the back, but this makes the RF 400mm lighter than the EF 400mm F2.8L IS USM III with adapter would weigh. So that’s an advantage of buying the RF version. Another reason for RF users is that with the RF 400mm F2.8L IS USM you don’t have to use an adapter. This saves an additional part where play can occur or where moisture and dirt can penetrate. That play can count even more if you also use teleconverters. A disadvantage is that you cannot use the lens on SLR cameras. Also you cannot use for example the handy EF to RF adapter with circular polarization filter. On the other hand, the RF 400mm F2.8L IS USM is equipped with its own filter holder on the back for 52mm drop-in filters.


We have already tested the Canon EF 400mm F2.8L IS USM III. The Canon RF 400mm F2.8L IS USM has the same optical design and that means this is a formidable lens. However, it is a pity that Canon has not just taken an extra step in converting EF to RF. What is clearly missing is a Control Ring. This is something that makes RF lenses functionally slightly better than EF lenses. It is difficult to explain that precisely this capability that is lacking on one of the most expensive RF lenses. Canon could have gone a step further by not attaching a simple tube to the lens but by installing a switchable teleconverter. That would have made the lens even more expensive, but at this price €1000.00 extra does not matter much anymore. For RF users who already have the EF version of this lens, there is no reason to upgrade, and anyone who also uses a 5D or 1D series EOS or an EF mount video camera, the RF is even less attractive. Nevertheless, there may be a good reason for some photographers to upgrade. The RF version has more contacts for data transfer and power supply between the camera and the lens. As a result, the RF 400mm may work better with very fast cameras such as the EOS R3, which can shoot at 30 frames per second.


The Canon RF 400mm F2.8L IS USM is hardly different from the EF version in terms of build. The additional ring needed to bridge the distance from the EF mount to the RF mount is even strikingly not white, but metal-colored. This gives you the feeling even more of working with an EF lens with adapter. All the controls are also identical to those of the EF version, from the wide focus ring, the ring for selecting one of the two presets and the four focus-hold buttons just before that to the switches for setting the focus, the focus range, the speed of the manual focus and the image stabilization. 


The optical design is identical to that of the FE version and has 17 elements in 13 groups. The lens contains 2 fluorite elements and 1 lens element made of Super ED glass. The elements have a Super Spectra coating, and both the front and rear elements have a fluoro coating to repel moisture and dirt. The diaphragm has 9 blades. The Canon RF 400mm F2.8L IS USM has a 52mm drop-in filter holder at the rear and comes with a clear filter that should be used if no other filters are installed. The Canon RF 400mm F2.8L IS USM is of course weatherproof with gaskets around all moving parts and an additional gasket on the mount. It also has image stabilization that, according to CIPA standards, should be good for 5.5 stops.


Fast and accurate autofocus is very important for sports and nature photography. The Canon RF 400mm f/2.8L IS USM has the same autofocus capabilities as the EF version. The focus ring can be used for the direct correction of the autofocus, and there are even three sensitivities adjustable. This allows you to choose between slow and very precise setting or making quick adjustments over longer distances. Also, two focus points can be quickly pre-programmed so that you can go directly to them when necessary. The white ring for the focus ring lets you go directly to one of these two points.

2.5 meterS

The shortest setting distance of the Canon RF 400mm f/2.8L IS USM is 2.5m. This is the same as with the EF version, and the maximum magnification you can achieve with it is 0.17x. So that’s not really suitable for macro. Many nature photographers therefore often have an extra body with a shorter (zoom) lens at hand to take pictures of situations that suddenly take place nearby. When using teleconverters, the shortest setting distance remains the same, but the field of view becomes smaller. This will improve the maximum magnification.


The image quality of the Canon RF 400mm F2.8L IS USM is particularly good. We can see this not only from the MTF graphs, but we also know from an earlier test of the optically equivalent EF 400mm F2.8L IS USM III. The sharpness is even over the entire field of view and hardly changes between F2.8 and F11. What does decrease is the vignetting, which at full aperture is almost two stops, but at F5.6 is already less than 0.4 stops. This high image quality, with excellent sharpness and contrast even at full aperture both in the center and the corners, ensures that you can also combine this lens with the 1.4 and 2x teleconverters. Although they cause a small decrease in image quality and slightly less good corners at full aperture, the sharpness is still high. The image quality you get in combination with the converters is better than if you cropped the image.

Canon RF 400mm F2.8L IS USM
field of view (diag)


sensor formatfull frame
min. setting distance250 cm
filter diameter

52mm (rear)

diaphragm blades9
image stabilizeryes
dimensions (dxl)168×367 mm
weight2890 gr
mountCanon RF

usable with converters

importer or

list price€ 13,219.00
chromatic aberration/5
final score

ConclusiON: REVIEW Canon RF 400mm F2.8L IS USM

The Canon RF 400mm F2.8L IS USM is an excellent lens, but there are hardly any reasons to choose this lens over the EF version.

The Canon RF 400mm F2.8L IS USM is an excellent lens but optically no better than the EF 400mm F2.8L IS USM III. And it doesn’t have to be, because that lens is only available for a short time and can hardly be improved optically. The RF version may offer slightly more functionality with extra fast cameras like the EOS R3, thanks to the extra contacts, but it does lack a Control Ring compared to other RF lenses. Whether you choose an EF or the RF version therefore does not depend on whether you photograph with a camera from the R series, but whether you also work with other cameras. If you film with a Canon film camera with EF mount or work with a 1Dx in addition to an R5, you might want to opt for the EF version. Then you have to buy an additional adapter, and that is of course not necessary with the RF version.


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