Exploring Canon's intelligent autofocus system

How does Canon's intelligent autofocus work, which Canon cameras use deep learning AF, and how can this latest Canon camera autofocus technology help you to capture better shots and improve your hit rate?

Originally developed for the Canon EOS-1D X Mark III, the intelligent autofocus system with deep learning algorithms is also present in the EOS R3, EOS R5, EOS R6, EOS R7 and EOS R10. Wedding, fashion and portrait photographer and Canon Ambassador Félicia Sisco has already found it invaluable.

"It was crazy, with wedding guests jumping up and down all over the place," Félicia says of a recent assignment. Such a scenario might sound like an autofocus nightmare, but Félicia's Canon EOS R5 never missed a beat. In fact, she has been impressed with the EOS R5's AF since her first experience with it. "The first time I used the EOS R5 was for a very difficult fashion shoot with lots of movement," she says. "The autofocus was incredible. Now I'd feel lost without it." Félicia has also used the Canon EOS R6, which utilises the same artificial intelligence autofocus system.

Canon Europe Senior Product Specialist Mike Burnhill explains that this latest iteration of the EOS iTR AFX system uses "deep learned" artificial intelligence. The system is based on an algorithm that teaches itself by scanning millions of images. The system essentially learns how to recognise the heads of people, even if they're skiers wearing goggles, racing drivers wearing helmets, or gymnasts upside down or even facing away from the camera. Deep learning is a huge leap forward from the intelligent autofocus systems of previous Canon cameras.

At the busy wedding shoot using the Canon EOS R5 and EOS R6, Félicia was delighted at how the autofocus system is every bit as good in both cameras. "I love that the cameras have autofocus points everywhere, across the whole frame," she says. "I no longer need to line up the eye of a person with a particular AF point in the camera. The system automatically detects the face and the eyes and jumps straight to them."

Over a career spanning 40 years, Félicia's favourite lenses have long been the Canon EF 50mm f/1.2L USM and EF 85mm f/1.2L II USM primes, particularly in situations where an ultra-tight depth of field demands critically accurate focusing. "Photographers using older kit have told me they have problems autofocusing with these lenses and getting consistent results. I show them the Canon EOS R5 with the RF 85mm F1.2L USM lens and there's no longer a problem."

The end result is that the Canon EOS R5 and EOS R6 can acquire autofocus in a class-leading 0.05 seconds, after which tracking performance is superb. The EOS R3's autofocus is even more responsive. It's able to focus in as little as 0.03 seconds and in light as low as -7.5EV, making it the fastest and most sensitive AF system in the world for a full-frame camera.¹

Autofocus tracking works with spectacular speed, accuracy and consistency in both face-detection and eye-detection modes. "I was shooting a model on a swing, so she was moving backwards and forwards, as well as up and down," says Félicia. "The camera's autofocus instantly locked on to her eye and tracked her flawlessly as she moved."

It's even more of a challenge when obstacles get in the way. Félicia used to struggle to maintain autofocus at weddings when tracking people on the move while flowers, confetti and rice were being thrown, often obscuring their faces. Now, she says, "it's incredible. With the EOS R5 and EOS R6 I was using, autofocus stays locked on the eyes and faces of people even when the camera can't see them."

In addition to eye and face-tracking abilities, the EOS R3, EOS R5, EOS R6, EOS R7 and EOS R10 add body and animal detection. Again, millions of existing images needed to be scanned to build up a sufficiently large database. It was a particularly complex task, says Mike. "Just for dogs, you could have a Chihuahua or a Great Dane. If you didn't know they were the same species, would you put them together? Then there are birds. You've got a hummingbird and an ostrich, an owl and a penguin. They're very different shapes, but they're all birds."

The technology rises to the challenge, as wildlife photographer Robert Marc Lehmann attests: "Everything that was hard to achieve for the last couple of years in terms of [photographing] moving animals just became very easy. This is going to be the game-changer for wildlife photography. Even with a sea eagle in flight coming from 100 metres away, the autofocus locks on and keeps [the subject] in focus all of the time. Even during intense turns and everything, it keeps it totally in focus. I just have to press the shutter button and rush out images at 20 frames per second."

The EOS R3 introduced vehicle detection as a further autofocus priority, and this option has since been added to the EOS R5 and EOS R6 via a free firmware update. It is also available in the EOS R7 and EOS R10.

Primarily designed for motorsport photography, the system can rapidly detect and track racing cars and motorbikes. "In addition to open-cockpit Formula-style cars, the system can recognise rally cars and touring cars," Mike explains. "As these are based on commercial cars, that means the majority of everyday cars can be detected as well.

"It can also recognise most kinds of motorcycle, although it perhaps won't pick up, say, a scooter or a monkey bike, because they don't fit the standard bike template."

When spot detection is enabled, the camera will even prioritise the helmet of a motorbike rider or the driver in an open-cockpit car, Mike adds. "If you're photographing a motorcyclist or a Formula One car, you want the focusing point to be on the person's head, rather than the nose of the car or the headlight of the bike. So that's what the camera's been given an option to do."

The EOS R5 and EOS R6 use Whole Area AF for intelligent subject detection and face-tracking, although you can choose a starting point for the camera's autofocus. Simply highlight the subject with the centre AF point, and the camera will track it from there.

With the versatile Flexible Zone AF that's available in the EOS R3, EOS R7 and EOS R10, however, automatic subject detection can be used in a smaller, specific part of the frame.

"You're now able to customise the size and shape of the AF area," Mike says. "So you can go from something that's slightly bigger than the centre AF point to an area that almost covers the entire frame.

"You can choose a square, a vertical or a horizontal rectangle, and even a row of AF points. If you were photographing a 100-metre sprint in athletics, for example, you could just create a thin line of AF points across the centre of the image and then the camera would track whoever's winning, and then jump to their face as they get nearer."

Autofocus speed and convenience are taken to the next level with the Eye Control AF system in the EOS R3. The system uses an array of infrared LEDs to monitor the position of your eye as you look through the viewfinder, and can use this to set or switch the AF point according to what you're looking at, when you choose to engage the feature. Once it has acquired the subject, it can take over and start tracking that subject.

When you want to switch to a different subject, just release the shutter button, then half-press it again to reactivate the Eye Control AF system. Look at the new subject, and the Eye Control AF cursor will appear where you're looking. Press the shutter button fully, and the camera will use its hierarchical subject detection to focus on the new subject and track it until you release the shutter button.

As Mike explains, you don't have to keep looking at the subject when Eye Control AF is enabled, because it works hand-in-hand with the subject detection system. "Think of it as like using the mouse or cursor of a computer," he says. "You use it to click on your subject and then let the camera's software do its job. If you're photographing a person, you don't even have to look at their face, just somewhere on their body, and the system kicks in.

"It can automatically prioritise the eye, the face, the head and the body, in that order. If a person is wearing sunglasses, their eyes won't be visible – so the camera will focus on their face. If they turn around, it will track their head instead, and if they move behind someone else, the AF system will go to the body, and then back to the head, followed by the face and then the eyes. So it's doing all of that for you as the subject moves. It's choosing the best part of the subject that it can identify."

Some of Félicia's favourite shots are taken in very low lighting conditions or even in near darkness. She sometimes partially closes curtains when shooting indoors to further reduce the light, or shoots outdoors at night, all without the use of flash. "Whether there's light or no light, the autofocus just works," she says. "I don't need to worry, just shoot, and everything stays sharp." Indeed, with Félicia's Canon RF 85mm F1.2L USM lens, the Canon EOS R5 can autofocus in light levels as low as -6EV, and the EOS R3 as low as -7.5EV, equivalent to shooting in the dead of night under a quarter-moon.

For capturing the definitive moment, Mike says that intelligent autofocus gives you one less thing to worry about. "Taking a photograph is like juggling. You've got to balance focus, composition, timing and exposure. It's much easier to juggle two balls rather than three. With intelligent autofocus we're taking away one of the balls, so you don't have to concentrate on so many things. It makes things easier and less tiring, and you can get better results."

To sum up, Félicia says that the autofocus performance and reliability of the Canon EOS R5 and EOS R6 enable her to devote all of her attention to composition and timing. "I shoot with both eyes open. I want to share the emotion and to capture it. I have to be able to trust the camera in my hand as if it were part of me, and I trust the EOS R5 and EOS R6 implicitly. I can simply shoot and know that I'll get the results I want without worrying about technical problems."

Find out more about autofocus technologies in Canon cameras.

1. Calculated based on the results of AF speed tests in accordance with CIPA guidelines (results may vary depending on shooting conditions and lenses used). Relies on internal measurement method. Test conditions: • Brightness at time of distance measurement: EV12 (regular temperature, ISO 100) • Shooting mode: M • Lens in use: RF 24-105mm F4-7.1 IS STM. When shooting stills with manual shutter button operation • AF mode: Single-point AF (central) • AF operation: One-shot AF