The launch of the EOS R System with the Canon EOS R combined the best of the heritage of the Canon EOS range with the innovations of full-frame mirrorless technology, along with a suite of new RF lenses. For existing Canon shooters using EF and EF-S lenses, the transition to full-frame mirrorless has been helped by the selection of EF-EOS R mount adapters available, which not only allow these lenses to work seamlessly on EOS R System cameras, but add functionality and even improve the optical performance of lenses.
Fashion and portrait photographer Guia Besana, who exhibits across the globe and has published images in Le Monde, Newsweek and Marie Claire, regularly puts her collection of EF lenses to work on her Canon EOS R, using a mount adapter. Destination wedding photographer Katya Mukhina also appreciates the flexibility a mount adapter gives her with her kitbag, which includes a Canon EOS R. "I continue to use certain EF lenses because their lens characteristics are so unique," she says. "I'm also still using my Canon EOS-1D X Mark II [now succeeded by the Canon EOS-1D X Mark III], so keeping some EF lenses in my bag is more functional."
As the EOS R System family continues to grow, these two Canon Ambassadors share how they pair non-RF lenses with EOS R System cameras in the field, while Canon Europe Product Specialist Mike Burnhill outlines the specific features of Canon's three EF-EOS R mount adapters.
Offering full compatibility with Canon EF and EF-S lenses, all three EF-EOS R mount adapters enable photographers and filmmakers to continue to make full use of their existing lenses. The standard Mount Adapter EF-EOS R is Guia's adapter of choice, which she finds gives her everything she needs. "I have lots of different EF lenses and want to be able to use them," she explains. "The Canon EF 40mm f/2.8 STM lens is a good example because it makes the camera light and small to carry around for shots that I usually use as notes, in a reportage style."
The Control Ring Mount Adapter EF-EOS R adds a Lens Control Ring to the mount conversion, which enables users to customise functionality and adjust settings without taking their eye off the camera. It can be programmed to adjust shutter speed, aperture, ISO, exposure compensation or white balance. Positive or negative values can be assigned to either a left or right turn of the ring, and there's also the option of engaging the control ring setting only when half pressing the shutter release button to avoid accidentally adjusting settings during crucial moments.
"I really like the added flexibility of the control ring on EF lenses," says Katya. "Personally, I use the ISO function on the control ring for my lenses. It's very handy when you need to adjust light sensitivity in a split second when light levels change."
The third option, the Drop-In Filter Mount Adapter EF-EOS R, adds the ability to use drop-in filters, removing the need to fit filters onto the front of a lens. It's available with either a variable neutral density (ND) filter, a circular polariser or a clear filter for shooting without filter effects. This functionality proves especially useful for landscape or architectural photography with lenses that don't accommodate front element filter systems, such as the Canon EF 11-24mm f/4L USM.
EOS R System cameras intelligently process optical tolerances for both EF and RF lenses, recognising which filter is placed into a Drop-In Filter Mount Adapter EF-EOS R and accommodating for the optical changes. The geared wheel on the outside of the mount also allows the circular polariser or variable ND filter to be rotated inside the mount without having to disassemble the setup, Mike explains, which both saves time and protects the system from dust. The additional clear filter adds another layer of dust protection and allows the camera body to intelligently adjust for chromatic aberration and any convergence of light when shooting with the adapter.
When working on personal projects, Guia likes to be able to use her EF lenses in tandem with RF lenses. "I usually use a Canon RF 50mm F1.2L USM lens with the Canon EOS R, which I mount on a tripod," she says. "I then like to shift to EF lenses, such as the Canon EF 100mm f/2.8L Macro IS USM lens, and use it hand-held to explore a different point of view.
"Using the RF and EF lenses together has made me consider different ways of moving around a subject during the same session – something I wasn't really doing before."
Being able to stick with the same camera whichever lenses she chooses, she adds, also makes her post-processing workflow easier, as the files are consistent from the one camera.
Complementing the Canon EOS R's innovative tech with the optical quality of her favourite EF lenses frees Katya from focusing on technical elements, enabling her to put her energy into composition and connecting with her subjects.
"Recently I shot an elopement with the Canon EOS R and Canon EF 11-24mm f/4L USM lens using a mount adapter," she says. "I very much needed an ultra-wide angle, and this lens has very little distortion. I used a monopod and lifted the Canon EOS R up above the couple, who lay on the ice below. Since I could control the framing more accurately using the Canon Camera Connect app on my phone connected over the in-camera Wi-Fi, I shot more quickly, and the couple spent less time on the freezing ice."
Most photographers tend to keep the adapter on the body and then attach a lens, but there's no wrong way to use the mount adapters, unless you're shooting with a heavy telephoto. Any lens that has a tripod collar should have the camera mounted to it, rather than the lens to the body, says Mike, regardless of whether it has an adapter or not. "I have had no problems using the adapter," adds Guia. "It is very strong and easy to use. It feels compact, giving a sense of security even when you juggle around to use it in fast-paced moments."
The EF-EOS R mount adapters are unique because they don't confuse the signal running between the lens and camera body, says Mike, which allows the camera to communicate directly with the lens whether it's EF or RF – making for a "bilingual" system.
"Most adapters physically and electronically convert signals from one device to another," he says. "Information gets lost in translation, which is when things lock up and stop working. The EF-EOS R mount adapters are just a pass-through, so there's no performance drop. The camera then cleverly notices the lens that's attached to the adapter and communicates with the lens. Third-party adapters have firmware to communicate intelligently between lens and body, but this all takes time. With the Canon system there's very minimal latency, so it works – quickly and reliably."
So well does it work that, out of the 150 or so EF lenses Canon has produced, only eight older lenses do not retain full functionality when used with EF-EOS R mount adapters: the power zoom button does not work on the Canon EF 35-80mm f/4-5.6 PZ (1991), and the AF stop button does not work on seven, largely discontinued, lenses.* All other functions operate without a problem.
What's more, the technology behind the adapters can actually enhance the performance of EF and EF-S lenses. These lenses perform just as well on the EOS R System as they did with their original counterparts, if not even better, says Mike. "An EOS R System body uses a bigger list of built-in lens profiles, so it can automatically correct for more lens aberrations in-camera, producing better pictures straight out of the camera."
*The AF stop button does not work on the following lenses when used with EF-EOS R mount adapters: Canon EF 300mm f/2.8L IS USM (1999), Canon EF 500mm f/4L IS USM (1999), Canon EF 400mm f/2.8L IS USM (1999), Canon EF 600mm f/4L IS USM (1999), Canon EF 400mm f/4 DO IS USM (2001), Canon EF 200mm f/2L IS USM (2008), Canon EF 800mm f/5.6L IS USM (2008). All other functions operate as normal.