The Canon RF 400mm f/2.8L IS USM (Amazon, B&H) is primarily a photography lens, though it can be used for video.
In this article let’s take a comprehensive look at the important features and specifications of the Canon RF 400mm f/2.8L IS USM and see how good it will perform specifically for video, cinematography and filmmaking.
The aim of this article is to provide you with enough information and perspective so you can decide for yourself whether this lens is right for your film or video.
Important: This article is a comprehensive overview of the lens with available information; and an analysis based on our experience shooting for almost two decades. It is not a hands-on review. If and when we get hold of the lens we’ll be sure to publish a detailed review. If this is not your cup of tea you can stop reading.
Click to what you want quickly:
- TLDR;
- EF vs RF:
- Features:
- Control:
- Basics:
- What about Teleconverters and Extenders?
- Alternatives to the RF 400mm f/2.8L IS USM
TLDR;
What you need to know for video work about the Canon RF 400mm f/2.8L IS USM (Amazon, B&H):
- The Canon RF 400mm f/2.8L IS USM is a speciality super telephoto and close up lens.
- Constant aperture of f/2.8 will be great to work in low light.
- The lens stays sharp across the frame.
- Focus ring can be changed to fly-by-wire for follow focus work.
- The lens has 5.5 stops of Image Stabilization, and you can pair it with the stabilization in a Canon R camera (R5, R6, etc.) that has IBIS.
- Great for dual pixel autofocus for video.
- It exhibits breathing.
Can be great for the following types of filmmaking:
- Sports
- Wildlife filmmaking
- Documentary filmmaking
EF vs RF: What’s the difference?
Difference between the RF and EF mount
Both are lens mounts specific to Canon. Let’s take a look at some important distinctions.
Flange focal distance
The RF is a new lens mount, with a smaller flange focal distance.
Here’s how the flange focal distance compares:
| Mount | Flange Focal Distance |
|---|---|
| RF | 20mm |
| EF | 44mm |
EF lenses were designed for DSLRs. Now with the mirror gone, that’s space and weight savings. However, that’s not the only advantage.
Canon (and every one else) maintains the smaller flange focal distance allows for larger apertures (for some focal lengths), better corner to corner sharpness and reduced light fall off.
Ergonomics
RF lenses are supposed to be lighter, making them easier to handle for photography, but slightly problematic for video. Weight gives better stability and smoother movement for most use cases. For gimbal, drone and steadicam use, the lower weight is an advantage because a lighter lens puts less strain on motors, and the human arms that have to hold it up.
The RF mount is equipped with 12 communicator pins compared to 8 pin connection of the EF mount. Canon claims this contributes towards quicker autofocus, better AF tracking and improved image stabilization.
Canon has redesigned the focus actuators for a hassle-free filming. They claim the new Nano USM and Dual Nano USM have been designed for video. Canon claims that the introduction of these actuators in RF lenses will result in a quieter and quicker autofocus.
The last major change is in the optics. Canon have redesigned the optics from the ground up to account for the smaller flange focal distance. This one simple change considerably changes the optical characteristics and challenges.
Naturally the prices of RF lenses match the high quality Canon have put into these series! The assurance is, the quality isn’t compromised, and with proper care Canon RF lenses should last for years. Let’s compare the EF version of the 400mm with its newer RF counterpart.
RF 400mm f/2.8L IS USM vs EF 400mm f/2.8L IS III USM
| Lens | RF 400mm f/2.8L IS USM | EF 400mm f/2.8L IS III USM |
| Filter Thread | 52mm Drop in | 52mm Drop in |
| Size | 163mm x 367mm | 163mm x 343mm |
| Weight | 2890g | 2840g |
| Lens Control | None | None |
| Closest focusing distance | 2.5m / 8.20 ft. | 2.5m / 8.20 ft. |
| Max. Aperture | f/2.8 | f/2.8 |
| Min. Aperture | f/32 | f/32 |
| Aperture Blades | 9 | 9 |
| Angle of View (Diagonal) | 06°10′ | 06°10′ |
The Canon EF 400mm f/2.8L IS III USM (Amazon, B&H) is slightly lighter and smaller than the Canon RF 400mm f/2.8L IS USM (Amazon, B&H). It is wise to remember that with the added weight and size of the adapter, the results will be even.
Canon actually claims that the RF 400mm f/2.8L IS USM lens is optically identical to the EF variant.
The RF version also supposedly has smoother and quieter autofocus with the USM autofocus actuator.
Features
Coverage
The Canon RF 400mm f/2.8L IS USM (Amazon, B&H) is a full frame lens. It is designed to completely cover a sensor the size of 36mm x 24mm.
If you are considering this lens for an APS-C sensor or other cinema camera, the effective focal length with a 1.6x crop will be 640mm. Check out this article for more information on the 35mm equivalent:
Focal Range
The focal length is 400mm. This is considered a super telephoto lens on a full frame 35mm sensor.
This focal length is useful for sports event coverage and wildlife filmmaking. You might also want to use it to film the moon at night.
Aperture
The maximum aperture is f/2.8. The minimum aperture is at f/32.
Resolution
From Canon’s official MTF charts:
The Canon RF 400mm f/2.8L IS USM (Amazon, B&H) is sharp in the center and stays that way throughout. This is an L series lens performance. It doesn’t get any better than this.
With the variance in the Sagittal and Tangential lines, you can infer (somewhat) that the bokeh will be buttery smooth. You can obliterate most backgrounds at f/2.8.
If you are curious and want to read the MTF chart for yourself. Here’s a guide on how to read them easily.
Close Focus
The closest focusing distance is 2.5 meters or 8.2 feet. The lens comes with a three-position distance limiter switch with two settings:
- Telephoto (7m – infinity) and
- Full (2.5m – infinity)
The smaller the distance, the faster the autofocus will be. I think for normal work the “Telephoto” setting should be good enough.
Image Stabilization
Canon claims the Canon RF 400mm f/2.8L IS USM (Amazon, B&H) has up to 5.5 stops of Image stabilization (IS).
5 stops? 8 stops? What are these stops?
How do you calculate Image Stabilization? Check this out:
Pairing the 5-axis IBIS-equipped Canon EOS R5 or Canon EOS R6 with an IS-equipped lens can deliver 8-stops of combined IS. This can be toggled on and off if you choose so.
It’s obvious the best stabilization is realized when an RF lens with IS is combined with an R-body camera with IBIS. E.g., the 400mm f/2.8L will be more stabilized on a Canon EOS R5 over a Red Komodo (which also has an RF mount).
RF 400mm f/2.8L IS USM has 3 IS modes, (probably not for video). Here’s the official word:
There are three Image Stabilization mode settings, for control of shake-correction — each can be applied with the sliding, 3-position switch on the lens barrel. Mode 1 provides general shake-correction for stills and video, with the continuous stabilization correction visible in the electronic viewfinder whenever it’s active. Mode 2 is designed for stabilization when deliberately panning, providing correction for lens/camera movement that’s perpendicular to the photographer’s intentional panning movement. And Mode 3 provides immediate shake correction, but only when the shutter is actually released — so the effect of stabilization is not visible in the viewfinder, between shots
Canon USA
Control
Manual focus system
By default the Canon RF 400mm f/2.8L IS USM (Amazon, B&H)) is set to ‘fly by wire’.
The RF 400mm f/2.8L IS USM has 3 different speed setting of the manual focus ring. You can switch between these settings using the lens switch on the body. The Mode 1 has the fastest response i.e. – minimal rotation of the manual focus ring results in significant shifts in actual focus. The Mode 2 and 3 settings add sensitivity, allowing finer focus control as the ring is rotated.
The RF 400mm f/2.8L L also has two focus presets that you can set and switch back and forth using the focus preset ring on the lens body.
Even though the Canon RF focus ring is technically a ‘focus by wire’ system, the RF lenses are the first line of lenses in the world which have enabled turning focus by wire off.
What is the meaning of focus by wire and fly by wire?
Focus by wire: Let’s say you turn the focus ring to change focus from point A to B. You’d expect the focus to shift accordingly. When you stop point B will be in focus. Now bring the focus point back to A and try again, but at a different speed. Slower or faster, doesn’t matter. Now, even if you precisely rotate to the exact same degree, the focus will not be on point B! The speed of rotation determines which point it is focused on. That’s just completely useless for follow focus work. If an actor or person moves at a different speed, evens lightly, you’ll never get the same focus. Avoid focus by wire lenses like the plague (for video work).
Fly by wire: The distance of focus shifted is directly proportional to the speed at which the ring is turned. This is how a manual focus ring is supposed to operate for video and cinematography.
How to change to fly by wire on RF lenses
You can switch to ‘link to rotational degree’ where the focusing distance will be directly proportional to the rotational degree regardless of the rotational speed.
It is a quick two-step affair that requires you going into the Canon menu and switching the RF manual focus ring sensitivity to ‘linked to rotational degree’ instead of ‘varies with rotational speed’.
This feature will be exceptionally useful for anyone who wants absolute control over the focus ring.
This feature makes an RF lens a game changer for many videographers, filmmakers and cinematographers.
Autofocus system
Dual Pixel Autofocus is, without a doubt, one of the most revered video autofocus systems in the world. Canon claims the new AF actuators will help focusing to be smooth and phantom-quiet.
This needs to be tested, of course. Will it scare the birds away?
While in autofocus mode, you can still rotate the manual focus ring for finer focus adjustments. The dual pixel AF system works better (in theory) than original EF lenses on native EF bodies. I don’t think anyone will be disappointed with its performance.
Basics
Filter Thread
The Canon RF 400mm f/2.8L IS USM (Amazon, B&H) has a drop in filter thread diameter of 52mm.
Build Quality
The majority of the lens exterior is plastic, though the lens doesn’t feel cheap. I would be very surprised if it wasn’t at least equal to the EF variant.
The optical design consists of 17 elements in 13 groups, including two Fluorite and one Super UD element.
Size and Weight
The Canon RF 400mm f/2.8L IS USM (Amazon, B&H) has a diameter of 163 mm and a length of 367 mm. It weighs around 2.89 kgs. This is one hefty lens but that shouldn’t surprise anyone.
Weather resistance
Canon claims that all L-series lenses are weather sealed. But then again, this only holds true if the camera body you will be using is also weather sealed. No camera is truly and officially weather sealed, so the best you can hope for is reliable weather resistance.
This is an L series lens and you can expect it to perform as such.
What’s in the box
This is what you get in the box (other than the lens):
- Lens Cap E-180E
- Lens Dust Cap RF
- Drop-in Screw Filter Holder 52(WIII) with 52mm Protect Filter
- Lens Hood ET-155(WIII)
- Lens Soft Case LS400
- Lens Wide Strap B
That’s all. The lens is big enough to have a tripod support. And it would have been great to have one in the box.
What about Teleconverters and Extenders?
Canon sells two RF extenders:
You get an effective focal length of:
| Extender | Effective Focal Length | Loss of light |
|---|---|---|
| With the RF 1.4x | 560mm | 1 stop |
| With the RF 2x | 800mm | 2 stops |
Canon claims both autofocus and image stabilization work well with the extenders.
Alternatives to the Canon RF 400mm f/2.8L IS USM Lens
There really is no alternative to the Canon RF 400mm f/2.8L IS USM (Amazon, B&H).
You can also look into the RF 100-500mm f/4.5-7.1L IS USM (Amazon, B&H) if you need the versatility in focal length but it will come at the expense of a wide aperture. It is lighter, cheaper and smaller, though. But not apples to apples.
I hope you found this overview of the Canon RF 400mm f/2.8L IS USM (Amazon, B&H) useful. If we have missed out on something, please let us know in the comments below.
