Alongside the 45Mp EOS R5 and 20Mp EOS R6, Canon has announced the RF 600mm F11 IS STM and RF 800mm F11 IS STM lenses. These are the world’s lightest 600mm and 800mm lenses with autofocus.
They are also compatible with the new Canon Extender RF 1.4x and Extender RF 2x teleconverters which take their focal lengths to 840mm/1,1200mm and 1200/1600mm respectively.
And at £749.99 / €869.99 / $699 and £979.99 / €1,149.99 /$899 respectively, they’re not crazily expensive. So what’s the catch?
Well, they both have a maximum aperture of f/11. In fact, they have a fixed aperture of f/11, so that’s the only setting available. We’ve become used to debating the pros and cons of f/4 and f/2.8 lenses, and fixed (maximum) aperture versus variable aperture lenses, but we’re in new territory with fixed f/11 optics.
An aperture of f/11 might seem pretty limiting, it’s certainly not an ideal choice of lens for shooting motorsports on a wet November day in the UK, but what about in the summer?
Well, Canon is claiming 5EV shutter speed compensation with the 600mm lens and 4EV with the 800mm lens. That means you need to use shutter speeds of at least 1/20sec and 1/50sec respectively. Even on a horribly overcast and rainy day in July, I only need to push the sensitivity to ISO 500 to get a shutter speed of 1/50 sec at f/11. And in sunnier conditions, 1/200-1/500sec is possible at ISO 200.
Of course, if your subject is moving, you may need a faster shutter speed, so you’d need to push the ISO up, but these days ISO 1,600 delivers results that we could only have dreamed of a few years ago.
Read our Canon EOS R5 review
Read our Canon EOS R6 review
Canon RF 800mm f11 IS STM: Collapsed for transport 
Canon RF 800mm f11 IS STM: Ready for action
Cost, size and weight
A new top-flight 600mm f/4 lens is going to set you back at least £12,000 / $12,000. That’s way beyond most people’s budget. It’s more likely to be something you’d hire, but even then you’re looking at around £200/$200+ a day. If you’re going on safari for a couple of weeks you’ll need it for longer but you’ll probably be able to get a deal, HireACamera does a two-week hire of the Canon EF 600mm F4L IS II USM for £565.20, for instance. That’s worth considering for a once-in-a-lifetime trip.
However, many photographers opt for a zoom lens. The Sigma 150-600mm f/5.6-6.3 Sport DG OS HSM is a popular choice at £1,249/$1,379. It weighs 2860g, just over 3x the weight of the Canon RF 600mm f11 IS STM and more than twice the weight of the RF 800mm F11 IS STM. But at the 600mm end, the maximum aperture is f/6.3, that’s 1.6EV faster than the Canon lenses.
Pop the Sigma lens on a 1.4x teleconverter (it’s often sold with one) and you’ve got focal length maximum of 840mm and a maximum aperture of f/9. That’s less than a stop smaller than f/11. Suddenly the weight saving of the RF 800mm F11 IS STM looks more appealing.
The new Canon lenses also have the convenience of a collapsible design. When collapsed the 600mm measures 199.5x93mm and the 800mm is 281.8×101.6mm, both significantly less than the 290x121mm of the Sigma 150-600mm.
So portability is an attractive feature of the new f/11 optics.
Canon RF 800mm f11 IS STM: Collapsed 
Canon RF 800mm f11 IS STM: ready for action
What about the Autofocus?
The Canon RF 600mm F11 IS STM and RF 800mm F11 IS STM lenses both have stepping motor (STM) autofocus systems built in, and the new Canon EOS R5 and EOS R6 can focus at down to -6EV and -6.5EV respectively. They are designed to work together, and canon is aiming them at wildlife photography enthusiasts, but we’ll have to wait to do some real-world testing before we know how practical a proposition they are for photographing animals on the move.
Crazy or genius?
Initially, the RF 600mm F11 IS STM and RF 800mm F11 IS STM lenses seem pretty crazy, but when you consider how digital cameras have developed with much better noise control and take into account how image stabilisation systems have become, perhaps we’re actually looking at the future of lenses? Or at least the future of more affordable alternatives to long telephoto lenses.
Canon RF 600mm f11 IS STM Specifications
- Announced: 9th July 2020
- Lens mount: RF
- Lens construction: 10 elements in 7 groups
- Format: Full-frame
- Number of aperture blades: N/A
- Maximum aperture: f/11
- Minimum aperture: f/11
- Closest focusing distance: 4.5m
- Maximum magnification: 0.14x
- Dust/moisture resistance: No
- Filter size: 82mm
- Compatible Extenders: Extender RF 1.4x (840mm and aperture f/16), Extender RF 2x (1200mm and aperture f/22)
- Dimensions (length x maximum diameter): Extended: 269.5 x 93mm, collapsed: 199.5x93mm
- Weight: 930g
Canon RF 800mm f11 IS STM Specifications
- Announced: 9th July 2020
- Lens mount: RF
- Lens construction: 11 elements in 8 groups
- Format: Full-frame
- Number of aperture blades: N/A
- Maximum aperture: f/11
- Minimum aperture: f/11
- Closest focusing distance: 6m
- Maximum magnification: 0.14x
- Dust/moisture resistance: No
- Filter size: 95mm
- Compatible Extenders: Extender RF 1.4x (1120mm and aperture f/16), Extender RF 2x (1600mm and aperture f/22)
- Dimensions (length x maximum diameter): Extended: 351.8×101.6mm, collapsed: 281.8×101.6mm
- Weight: 1260g