The benefits of using Canon RF lenses for video

When the Canon EOS R System was being developed, the design of the RF lenses came first. Canon's engineers set out to create the ideal lens, and the new RF mount combined with the EOS R System's full-frame mirrorless architecture allowed them to realise their goal.

The RF mount enables a new freedom in lens design, where large apertures, high resolving power and cutting-edge components are combined to create unique optics for shooting video and stills. It's not just the exceptional image quality of RF lenses that leaves a lasting impression – they are beautiful to use, too. The 12-pin RF mount expands the quantity and speed of communication between the lens and the camera, bringing an enhanced level of autofocus, image stabilisation and customisable control that make RF lenses the perfect choice for video capture.

Four RF lenses were available at the launch of the Canon EOS R System in 2018 and the range of RF zooms and primes has grown exponentially since then. Revolutionary lenses such as the Canon RF 600mm F11 IS STM and RF 800mm F11 IS STM super-telephotos, and the RF 5.2mm F2.8L DUAL FISHEYE virtual reality lens have opened up new opportunities for creative filmmaking.

With its game-changing 8K video and 45MP photo resolution, the Canon EOS R5 set a new benchmark for full-frame hybrid camera performance. But it wouldn't have been possible to realise some of the EOS R5's uncompromising capabilities if it wasn't for the RF mount. The EOS R5 C and Canon EOS C70 have refined that successful formula, bringing RF capabilities to the Cinema EOS line of video cameras.

The RF lens range has also expanded to cover professional video production. The Canon RF Cine Prime lenses mirror the EF-mount Cine Prime series, but they're bolstered by the benefits of native support for the RF mount. The seven RF Cine Primes, which together span 14mm to 135mm, share the same exceptional image quality, bright T-stop values, geared rings and focus throw as their EF stablemates, and also offer the advanced communication between lens and camera that is only possible with the RF mount.

Here, we look at some of the benefits that RF lenses can bring for videographers.

RF lenses share the same large 54mm internal diameter as Canon's EF lenses, but they have a shorter flange distance from the mount to the camera sensor.

Compared with the 8-pin EF mount, the RF mount's 12-pin connection provides more communication power between the lens and the camera. This enables a number of improvements, such as more responsive autofocus and real-time Digital Lens Optimisation (DLO).

The Canon RF Cine Prime lenses offer the same focal lengths and T-stop values as the EF Cine Primes and Sumire Primes but benefit from the advanced communication capabilities of the RF mount. "Although lens information is outputted to the camera when you're using CN-E lenses, the increased communication speed and bandwidth that you're getting with the RF mount allows a lot more information to be transferred," says Ram.

"One of the advantages of this is the ability to apply in-camera electronic distortion correction. That's not something that's available on the CN-E Primes.”

The faster communication also enables a sophisticated level of image stabilisation. A number of RF mount cameras feature In-Body Image Stabilisation (IBIS) which works in co-ordination with an IS lens to deliver up to 8-stops of stability. IBIS also adds stabilisation for those shooting with non-IS lenses.

"Gimbals will always have a place," says Ram. "If you're sprinting after an athlete or if you're working with the camera mounted to a vehicle, for example, then a gimbal will do a better job than any human being could when shooting handheld. But for typical run-and-gun filming, most people would find the new level of IS to be more than sufficient. If you're using a telephoto RF lens, you'll certainly see a huge difference with the Canon EOS R3, EOS R5 or EOS R6 Mark II."

The large elements used in a fast RF lens result in a heavier focus group, but the Nano USM or Dual Nano USM actuators offer a powerful, compact and quiet way to drive autofocus that's ideal for shooting movies. The STM AF actuator employed in other RF lenses gives smooth, near-silent focusing that's a real benefit when recording audio with a camera-mounted microphone.

"While there may still be people who are apprehensive about using autofocus for filmmaking, we've introduced many useful features into cameras that enable filmmakers to start to rely on the autofocus capabilities," says Ram. "If you're a solo shooter, Dual Pixel CMOS AF is a godsend. Filmmakers have come back to us to say how accurate they've found it, and how the image doesn't snap into focus with that obvious digital look."

Photographic RF lenses feature a dedicated control ring that can be customised with a range of camera controls, including aperture, ISO and exposure compensation. It provides an accurate way to adjust the key camera settings without having to take your eye from the viewfinder.

"You've got people who are coming to the EOS R System from the video side, and you've got the people who are coming to it from the photography side," says Ram. "The cameras and lenses have been designed so that they can be customised according to the individual's needs. For instance, guerrilla filmmakers may want to have the RF lens control ring assigned to either ISO or exposure compensation. That way, if they're moving between locations of varying light, they are able to control the exposure in the same way they would with a variable ND filter."

Also, when zooming, the 1/8-stop aperture adjustment and zero fluctuation eliminates exposure shift and makes it possible to alter the exposure with the aperture without the rapid changes in brightness that occur with every other non-cinema lens.

With their newly developed knurled, fixed ring design, Canon RF Cine Primes make handheld operation more comfortable, intuitive and efficient. "The CN-R PRIME LENSES lenses have a longer length than their EF Cine Prime and Sumire Prime equivalents," confirms Ram, "but it's a lot easier to grip the lens when you're attaching and detaching it."

The geared rings across all Cine Prime lenses provide greater control over existing RF photo lenses, as does the 300° long focus throw – features that are consistent across Canon's cinema prime lenses.

Importantly, having a native RF cinema lens range removes the need for a mount adaptor, allowing for a more seamless handling experience with Cinema EOS cameras. "Cinema lenses overall are heavier than photography lenses," Ram says, "and over a period of time you might end up with a more fragile connection between the lens, the adapter and the camera. That's true of any adapter from any manufacturer. So having that native RF mount gives you a more reliable connection between the lens and the body."

Mount adaptors can be used to team EF and EF-S lenses with an RF camera. Control Ring Mount Adapter EF-EOS R includes a customisable control ring, but Drop-In Filter Mount Adapter EF-EOS R, with its ability to use drop-in circular polarisers and variable ND filters, is perhaps the most appealing for filmmakers.

The combination of large diameter, short flange distance and upgraded communication has made it possible to create new kinds of lens designs. "Everyone at Canon is hugely excited about the possibilities," reveals Ram. "The Canon RF 28-70mm F2L USM lens is testament to that."

Capable of capturing incredibly sharp footage and equipped with a fast, constant maximum aperture, this high-performance RF lens is essentially four classic primes in a single zoom. "If you're a single shooter, you don't necessarily want to run around with a multitude of lenses and this one RF zoom can be used for almost all your requirements," says Ram.

Other pioneering lens designs enabled by the RF mount include the RF 5.2mm F2.8L DUAL FISHEYE stereoscopic lens for virtual reality productions and the ultra-light RF 1200mm F8L IS USM super-telephoto.

"I think that the trinity of professional f/2.8 L-series zooms – the Canon RF 15-35mm F2.8L IS USM, RF 24-70mm F2.8L IS USM and RF 70-200mm F2.8L IS USM – make a great starting point for most filmmakers," adds Ram. "The RF 70-200mm is probably my favourite of the three. Compared to the EF 70-200mm f/2.8 lenses, it has considerably reduced focus breathing, and the result is beautiful.

"There are some filmmakers who'll want imperfections in their image quality to add character, and they will tend to gravitate towards using old-school legacy glass or really old vintage lenses. But we find that the majority of people want to have a really crisp, high-quality image for their videos, especially in order to make the most of the 8K capability of the EOS R5 C. The RF lenses will definitely realise that level of resolution."

Ultimately, the image that viewers see on screen is what counts. This is where Canon RF lenses excel – particularly the Canon RF Cine Prime lenses, with their refined cinematic output. The CN-R PRIME LENSES lenses deliver the same remarkable clarity and clean optical performance as their CN-E Prime counterparts, making them perfect for 4K, 8K and HDR productions. They also render colours in the same way as the other cinema lenses, Ram points out, "which is reassuring if you're mixing lenses from across our range on a production".

Each of the RF Cine Prime lenses boasts a bright T-stop value and an 11-blade iris, enabling filmmakers to capture a cinematic shallow depth of field, along with sumptuous bokeh, halation and sun flares. "For anyone who wants to have a stable mount, amazing optical quality and have all of the capabilities that a cinema lens offers them, these are the perfect fit," Ram concludes. "We envisage them being used for a wide variety of professional video productions, from documentaries and drama to commercial work and music videos."