Canon RF 400mm f2.8L RF 600mm f4L review
Written by Gordon Laing
In this review I’m testing the two biggest and most expensive lenses for Canon’s EOS R mirrorless system to date: the RF 400mm f2.8 which costs $12000 or 12500 pounds, and the RF 600mm f4 which costs $13000 or 13400 pounds.
Yep, that’s a ton of money, but actually no different from the latest EF Mark III versions of the same lenses designed for EOS DSLRs, nor the equivalent models from Sony either. And while Nikon’s not yet released native Z-mount super-teles, the existing AF-S models are also in a similar ballpark. This is the cost of bright aperture, full-frame super-telephotos.
Now these kind of lenses are unashamedly aimed at professional or well-heeled sports and wildlife photographers. You’ll see them at the sidelines of every major sporting event or on location tracking-down exotic birds and animals. And while their price makes them a fantasy purchase for most of us, they can be affordable to rent for an event or trip, plus it’s fun to see top-end gear in action, so in a similar vein to supercar reviews, stick around to see what this sort of money can buy. As always the complete review is in the video below, but keep scrolling if you prefer to read a written version.
First things first: the RF super-telephotos launched in mid-2021 share the same optics as the EF Mark III versions launched in late 2018, as a super-telephoto design is much the same whether aimed at DSLR or mirrorless. So they share the same optics, the same controls, the same build, and the same price too.
The main physical difference is the addition of a built-in EF to EOS-R adapter, and Canon’s not even trying to hide that fact by colouring the extension in silver and grey. This adapter in turn adds 40-50g to their weight and 24mm to their length. You could of course use a separate adapter on the old EF models to mount them on an EOS R camera, but it adds a potential point of failure which may attract some pros to the RF versions.
Beyond this, native communication over the RF mount provides additional benefits. Most notably support for Dual Power Supply on future bodies, presumably starting with the R3, means more power can be delivered to the autofocus motors allowing them to run faster. Both lenses also feature a faster diaphragm system supporting burst speeds up to 30fps, as well as aperture control in ⅛ EV increments for video. Canon also quotes slightly improved stabilisation whether the body has IBIS or not. The RF super-teles are also compatible with the RF tele-converters if you need longer reach.
Like other RF lenses, the focus distance windows of the EF versions have been removed and in their place are digital scales on-screen or in the viewfinder. Unlike most RF lenses though, there’s no customisable control rings.
Ok, so here’s the RF 400mm f2.8 at the top and the RF 600mm f4 at the bottom, both without their lens hoods. The 400 measures 163x367mm and weighs 2890g, while the 600 measures 168x472mm and weighs 3090g. So they’re similar in diameter, but the RF 600 is roughly 10cm longer and 200g heavier.
Once you add their respective hoods, I thought the 600 felt noticeably heavier in my hands than the figures suggest, but at roughly 3kg each, they’re still way lighter than the Mark I and II EF models.
Back in 2018, Canon made significant weight savings on the Mark III EF versions by exploiting modern optics as well as shifting the balance more to the middle, making them much easier to handle. The new RF versions inherit this design, which is also similar to Sony’s approach on its mirrorless super-teles.
Indeed while the older versions were very much the kind of lenses you’d have to use with a stand, you can just about swing these newer ones around handheld, albeit for short periods.
Both lenses share the same controls, with generously wide and smooth manual focusing rings, a spring-loaded ring control for motorised manual focusing or preset distance jumps, and four focus hold buttons.
Both lenses share the same control panel too, seen here on the 600 f4, including distance limits for the autofocus, three speeds for the motor-assisted manual focus, and a set of buttons and switches to preset the ring control distance. I’ll show you all of this working in a moment.
Like most super-telephotos, filters are accommodated via a drop-in system and both new RF super-teles unsurprisingly take the same 52mm filters as the older EF versions.
Both RF super-teles are also equipped with the same built-in tripod foot with quarter and ⅜ inch threads, but sadly still no Arca Swiss dovetail carved into them. They’re not removable, but allow the lens and camera to rotate very smoothly through 360 degrees with solid clicks at 90 degree intervals. The feet also double-up as carrying handles, although there’s also lugs on the barrels for attaching a supplied strap.
Both lenses are supplied with substantial cylindrical hoods that clip onto the end of the barrels and are screwed in position. They offer great protection, but obviously transform them into even larger objects. Canon sells optional shorter hoods if you need something less likely to clobber nearby photojournalists as you swing them around. The hoods also reverse over the barrels for transportation, leaving the supplied padded caps to slide over to protect those huge lovely front elements.
The hoods are also tipped with a rubber ring at the end, allowing them to be stood up quite securely without damaging the lens. That’s the 600 on the left with its supplied bag alongside and now here’s the bag for the 400 with the lens inside. Canon switched from rigid flight cases to soft padded shoulder bags with the Mark III EF models and the RF versions inherit them here. They’re well-padded with comfortable carrying handles and a single strap to carry them over your shoulder. Unzipping a large flap allows you to access the lens with the hood reversed over the barrel. Canon was obviously thinking of the future RF versions when designing the bag as it cunningly left enough space at the top to accommodate their slightly longer length. Unfortunately this means there’s now no longer enough room to pack them away while a teleconverter is mounted, and like the EF models, there’s also no space to include a mounted body either, so you’ll need to carry that separately. I’d have preferred some means to accommodate a body in the bag even if it wasn’t mounted to the lens.
Ok, now for some focus tests, starting with the 400 2.8 wide-open on an R5 body, autofocusing using Single AF and a central area. Even with a very close subject, it’s quick and pretty confident. And for comparison, here’s the 600 f4 at f4 on the R5 under the same conditions and this time even though the bottle is at the minimum focusing distance, there’s no struggle.
Switching to manual focus, both lenses offer three different speeds. Notice the digital distance scale rather than relying on the mechanical window on the older EF lenses. The slowest of the three speeds allows for very precise adjustments.
If you prefer a smoother manual focusing experience with a constant speed, both lenses are also equipped with a Power Focus or PF mode which uses the spring-loaded ring control to rack focus in either direction at one of two speeds depending on how far you twist it. This is the 400 2.8 and now for comparison, here’s the 600 f4. It’s a useful feature and you can of course activate focus peaking for assistance, but at these unforgiving focal lengths and apertures, it’s still easy to overshoot. You can of course use the same power focusing during movies, and with the two speeds, but again it’s easy to overshoot.
Canon’s thought of that though and both lenses alternatively allow you to preset either one or two focus distances activated by twisting the control ring left or right. This allows you to precisely return to an exact distance – or distances – with a simple twist of the ring and you’re seeing it in action here with the 400 2.8 where I’ve preset on the label and the ornament, and now for comparison on the 600 f4. This feature is brilliant if you regularly need to refocus back to a fixed position where the action often happens, such as a branch being used by a bird to perch, and it also works for video.
The focus presets eliminate any chance of error, but Canon’s autofocus has become so good for movies that in most situations you can still rely on simply tapping on the screen to pull-focus to wherever you like. Here I’m just tapping between the bottle and the ornament on the R5’s screen while using the 400 2.8, and now for comparison, the 600 f4. In both cases, the AF system slows down to confirm when settling on the ornament, but if you prefer an instant snap back and forth, just use the preset feature.
Next for stabilisation, with Canon offering the same three modes depending on whether you want compensation full-time, or only in the vertical axis while panning, or only as you take the shot. Canon quotes 5.5 stops of compensation is possible on either RF lens – half a stop more than the EF versions – but that there’s no difference if you’re using a body with IBIS or not as sensor shift stabilisation becomes less effective at long focal lengths.
Here’s a shot I took handheld with the RF 600mm f4 on the R5 at 1/50 with stabilisation turned on. This was the slowest shutter speed I could successfully handhold a perfectly sharp result under close inspection and to match it without stabilisation on the day required a shutter speed of 1/800, so that’s four stops of compensation. To show you the difference with and without, here’s two images taken at 1/50, with IS enabled on the left and disabled on the right. If you’re shooting at lower resolutions or not looking as close, I found I could get a fairly decent handheld result at 1/13 or even ⅙ and you can see the images at ⅙ with IS enabled on the left and without IS on the right.
Before I dive into image quality and real-life handling, a quick look at the rendering of blurred areas, starting with a bokeh-ball test with the 400 2.8, wide-open at f2.8, and now gradually closing the aperture in one third EV increments where you’ll see the blurred lights in the background mostly retaining a nice circular shape and only really revealing the nine-bladed diaphragm system from f5.6 onwards.
And next the 600 f4, starting at f4, but moved a little further away due to its longer minimum focusing distance. Even from further away though, notice how the background appears tighter due to the longer focal length. And again gradually closing the aperture one third of an EV at a time, where again the nine-bladed diaphragm system is doing a good job at keeping a mostly circular opening for mostly circular blobs.
At longer subject distances, both lenses can still obliterate the background with a shallow depth of field. Here’s a portrait with the 400 at 2.8 where you can see the depth of focus in a thin band running across the beach with everything in front or behind becoming very blurred. And for comparison with the 600 at f4 from a longer distance to match the subject size on the frame. Notice how the background elements are tighter and larger at the longer focal length, allowing you to really concentrate on the subject alone.
These lenses are really designed for sports and wildlife though, so here’s a sequence of shots taken with the 400 at 2.8 on the EOS R5 using its mechanical shutter at 12fps, a speed which was maintained during the burst. I used Servo AF for continuous autofocus and set the area to human face and eye detection, with the R5 placing a box over Nick’s face throughout. Under close inspection, the majority are pin sharp, and on the occasional time a frame didn’t quite hit, the following one did, so there’s plenty of keepers to choose from.
And now for the 600 at f4, again using the same settings, although I briefly let go of the shutter a couple of times here to test reacquisition – I’ve not skipped any frames though for this presentation. As before I was relying on the R5’s face and eye detection and Servo AF set to Case 1 for general-purpose shooting. Like the 400 2.8, I enjoyed a very high, albeit not quite 100% perfect hit rate, but better results may be possible by adjusting the case settings.
Now for birds in flight, using Brighton’s fast and often erratic Seagull population. In all cases the aperture was set to the maximum, and I used face and eye detection with animal selected in the menu. Once again I used Servo AF Case 1, although again you may enjoy greater success by adjusting the settings, such as Case 3 with increased sensitivity; that said, as you’ll see I enjoyed a very high hit rate using the default settings, especially considering the birds quickly darted in and out of the frame.
This time I switched from the mechanical to the electronic shutter, unlocking the R5’s top speed of 20fps, although with the increased risk of skewing due to rolling shutter. Swinging a super-telephoto back and forth to follow a fast-moving bird is a worse-case scenario for rolling shutter and you’ll see some skewing on the buildings in the backgrounds of some shots. So if your subject has a lot of sideways motion you may prefer to shoot with the mechanical shutter instead.
In practical terms, the erratic nature of these birds rules out tripod or even monopod support for most shots, with you instead having to handhold for the quickest reactions. Unsurprisingly doing so with a 400 2.8 or 600 f4 grows old very quickly. Anytime you pick up either lens for the first time, you’re impressed by how light they are for the size, but after swinging one around for even just a few minutes, you’ll want to take a break. Of the two, the 400 2.8 proved more practical for this kind of relatively large and close bird, and in use is also a little lighter and more manageable especially when fitted with the hood.
Super telephotos are also ideal for capturing distant subjects with video, especially since Canon’s video autofocus is so confident. So before my final verdict, here’s an example I filmed at 4k 100p on the R5 and slowed by four times.Check prices on the Canon RF 400mm f2.8 at B&H, Adorama, WEX UK or Calumet.de. Check prices on the Canon RF 600mm f4 at B&H, Adorama, WEX UK or Calumet.de. Alternatively get yourself a copy of my In Camera book or treat me to a coffee! Thanks!