CANON RF 600mm f/11 AND 800mm f/11
You get ultra-long focal lengths in an affordable and hand-holdable lens, but it comes at a price. How well do Canon’s fixed-aperture superteles work in practice?
In politics, a move like this would be called “courageous”, but Canon’s fixed-aperture f/11 supertelephotos look to be more inspired than anything else. Yes, they demand a different way of working, but a handheld 800mm for full frame? C’mon!
Supertelephoto primes have always been specialty lenses. Unless you were regularly shooting sports or wildlife, it was virtually impossible to justify the cost. Of course, a smaller sensor size makes it easier to get to the supertelephoto focal lengths – essentially anything longer than 300mm – but even these lenses can still be quite expensive, especially the faster primes. As with 35mm film, supertelephotos for full frame sensors are big, heavy and very expensive regardless of whether the camera body is a DSLR or mirrorless.
How expensive? Well, Sony’s 400mm f/2.8 GM OSS for the FE mount will set you back just under $20,000 and the FE 600mm f/4.0 GM OSS is yours for $22,000. Nikon will happily sell you the F mount AF-S 600mm f/4.0G ED VR for somewhere in the region of $16,000 and Canon’s rival EFmount 600mm f/4.0L IS III USM is going to cost you around another three grand.
What about an 800mm supertele? Nikon’s AF-S 800mm f/5.6E FL ED VR is priced at around $27,000 and the Canon EF 800mm f/5.6L IS USM is a bit more ‘affordable’ at a little under $19,000. Sigma’s 800mm f/5.6 APO EX DG HSM – a real snip at around $9,500 – has recently been discontinued. But like all the lenses we’ve just mentioned, it was still big and heavy. The Canon EF-mount 800mm, for example, is 46cm in length and weighs 4.5kg. So, even though it has optical image stabilisation, you won’t be doing any handheld shooting with that beast.
No doubt all of this was in the
minds of Canon’s lens designers when they dreamt up the idea of a pair of RF-mount supertelephoto primes with a fixed aperture of f/11. In truth, the long telephoto isn’t overly complex optically, and much of the cost is related to them being built to withstand the wear and tear of hard professional use. Removing the diaphragm assembly alone isn’t going to make a massive difference to the bottom line. So Canon has completely rethought the supertelephoto to come up with a 600mm and an 800mm that are smaller, lighter and way more affordable than anything we’ve seen before for 35mm/full frame.
Apart from not having an adjustable diaphragm – the f/11 aperture is dictated by the internal structure – they feature a collapsible barrel design that makes them even more compact when not in use. A beefy locking ring is twisted a short way clockwise, so the front of the lens – which contains all the optics – can be extended to achieve the long focal length. The locking ring is then twisted back and you’re ready to go. Simple, but effective. Collapsed, the RF 800mm f/11 is a shade over 28cm long and, ready for action, it’s around 35cm. It weighs 1.26kg (compared to the EF lens’s 4.5kg), while the 600mm actually gets in at under a kilo and just 930g.
Both lenses have optical image stabilisation, so handheld shooting is quite feasible even with the 800mm. The OIS in the 600mm gives up to five stops of correction for camera shake, while the 800mm has four stops. However, for reasons that aren’t entirely clear, the f/11 superteles don’t have Canon’s ‘Co-ordinated Control IS’ where the OIS and the IBIS (in-body image stabilisation) in the EOS R5 and R6 join forces to extend the correction range and also compensate for movements in three additional planes to the standard pitch and yaw. As far as we can see, IBIS is effectively de-activated when these lenses are fitted to either the R5 or R6.
Applying the one-dividedby-focal-length law to establish the slowest ‘safe’ shutter speed for handheld photography, the 800mm’s starting point is 1/800 second and the four stops of OIS correction theoretically allows you to venture down to 1/50 second. With the 600mm, the five stops of correction means that you might be able to get away with shooting at shutter speeds as slow as 1/15 second. It certainly helps that neither lens is particularly heavy and they’re both very comfortable to hold. There’s no tripod mounting collar – presumably to save on both weight and cost – but there is a simple foot with a standard 3/8-inch threaded socket. You could leave a quick-release plate attached to this, which will allow and lens to be easily fitted to a tripod when needed. The main drawback is that switching to vertical framing has to be done with the tripod head, which often isn’t as easy as simply rotating the camera through a mounting collar. A ball-type head will be the best option here.
IN THE FIELD
So what does a fixed aperture mean in practice? We’ve been here before, when the mirror – or catadioptric – lens was once employed as a means of creating a more compact telephoto lens. As the name suggests, the mirror lens used a set of shaped mirrors to reflect the light rays back and forwards within the barrel as a means of achieving a longer focal length. A couple of conventional lens elements then perform final focusing. The mirrors prevent the fitting of a diaphragm, so the aperture in the centre of doughnutshaped back mirror – which allows light to pass through to the film or sensor – served as the fixed f-stop. This was certainly much more restrictive in the days of film when you couldn’t vary the ISO to assist with exposure control, and it’s the main reason mirror lenses were never really very popular, although many systems included a model… probably the most famous being Nikon’s Reflex-Nikkor 1000mm f/11. As an aside, Samyang still offers an ultra-compact 300mm f/6.3 mirror lens for the crop-sensor mounts… so with M43, for example, it’s effectively a 600mm.
In the digital camera era, the ability to change the ISO from shot to shot, and the steady improvement in high ISO performance (the R6, for example, delivers very acceptable results at ISO 51,200 or even ISO 102,400) make it easier to work around a fixed aperture. Additionally, Canon’s Dual Pixel CMOS AF autofocusing still operates at f/11, but obviously not using all the available measuring points (the small ‘aperture’ means that the AF area is reduced to roughly 40% horizontal and 60% vertical).
If you need to use faster shutter speed to freeze subject movement then adjusting the ISO is really the only control available for dealing with changing light conditions, and if there’s a bit more noise in the image, so be it. It’s only likely to be an issue if you’re planning to make really big prints and, with most of the likely applications for these lenses, this probably won’t be an objective. Conveniently, the multi-functional Control Ring – a feature of all RF mount lenses – can be assigned to adjusting the ISO (as well as shutter speeds or exposure compensation settings). Alternatively, switching to auto ISO control means the camera will set the sensitivity as required and, of
“IN THE DIGITAL CAMERA ERA, THE ABILITY TO CHANGE THE ISO FROM
SHOT TO SHOT,
AND THE STEADY IMPROVEMENT IN HIGH ISO PERFORMANCE, MAKE IT EASIER TO WORK AROUND A FIXED APERTURE.”
course, you can preset a working range if you don’t want to stray into the highest available ISOs.
IN THE HAND
Externally, the f/11 RF superteles are quite different from what we’d usually expect from Canon. For starters, they’re finished in black rather than off-white and the front has a textured leatherette-look covering, presumably to provide a secure grip when extending the barrels to the shooting positions. The Control Ring is picked out in silver and has a knurled grip while, immediately behind, is the manual focusing ring which, unsurprisingly, is fly-by-wire. Both lenses have the same on-barrel control panel comprising the AF/MF selector, a focus limiter and the image stabiliser on/off switch.
Also not surprisingly, the construction is almost entirely of reinforced polycarbonate, but the lens mount is stainless steel (and has the full complement of 12 contact pins). There’s no weather sealing, which is obviously a costcutting measure, but possibly problematic with lenses that will mostly only be used outdoors and probably in a variety of weather conditions too. Another cost-saving condition is the lack of a lens hood – if you want one, you’ll have to buy it separately.
Both lenses are very comfortable to hold and felt wellbalanced on the EOS R body we were using for testing. The 600mm really is no effort at all to carry and use, while the 800mm is a little more demanding because of its extra length and weight. In some situations, you might want to use a monopod for additional support, especially if you want stay targeted on a subject for any period of time while you wait for the shots you want. However, with its tiny angle-of-view – just three degrees diagonally – the 800mm is also much more of a challenge when it comes to viewfinding and trying to locate locatelocate a subject, especially small, flighty ones. Tracking requires a lot of practice and good eye-to-hand coordination… not to mention a very steady hand too. It’s also here that the superior subject tracking capabilities of the EOS R5 and R6 will be valuable too.
THE SUPER POWERS OF ‘DO’
The optical constructions comprise 10 elements in seven groups for the 600mm, and 11 elements in eight groups for the 800mm. Both employ a multi-layer Diffractive Optical (DO) element specifically designed to counter the diffraction effect of very small apertures. A micron-precise diffraction grating – which essentially works on the same principle as a fresnel screen – corrects for the extreme bending of the light rays caused by a smaller aperture, thereby reducing the blurring that ordinarily results from this amount of diffraction. The dual-layer arrangement eliminates flare, and the DO element is mated with a conventional element to correct for chromatic aberration. In fact, Canon says this arrangement is even more effective at correcting for chromatic aberrations than a fluorite element and, what’s more,
“OPTICALLY BOTH LENSES ARE SUPERB, WITH EXCELLENT SHARPNESS ACROSS THE FRAME – AS YOU’D EXPECT AT F/11 – AND NEGLIGIBLE VIGNETTING OR BRIGHTNESS
FALL-OFF.”