TECHNOLOGY

Exploring Canon's intelligent autofocus system

Find out how the intelligent autofocus system in Canon's latest EOS R System mirrorless cameras and the EOS-1D X Mark III "makes it practically impossible to miss a shot".
A photographer crouches to take a shot as a red sports car speeds down a desert road, dust billowing behind it.

Intelligent vehicle detection brings more freedom when it comes to composing motorsports shots, as Canon Europe's Mike Burnhill explains. "You can frame up a shot how you want it and then let the camera detect the car and track it through the frame, rather than having to set your AF point on a corner and then follow the car to where you want it."

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.

Head turned away from the camera and facing a full-length mirror, a bride adjusts the back of her dress with the help of her young bridesmaid.

The intelligent autofocus system in the latest EOS R System cameras is capable of recognising heads even with the subject's face turned away from the camera. Taken on a Canon EOS R5 with a Canon RF 50mm F1.2L USM lens at 1/80 sec, f/3.2 and ISO1000. © Félicia Sisco

Dressed in their wedding attire, a bride leans down to her young bridesmaid to rub noses playfully.

With the intelligent autofocus system, face detection works without the need for eye contact, and you can easily switch between different faces in the frame. Taken on a Canon EOS R6 with a Canon RF 85mm F1.2L USM lens at 85mm, 1/100 sec, f/2 and ISO3200. © Félicia Sisco

Automatic face detection

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."

Lightning-fast AF acquisition

Félicia is also impressed by the lightning-fast speed with which the intelligent autofocus can recognise and lock on to a face. Mike explains that the system scans the entire scene 120 times per second to build up a picture of the environment. Even during a burst of shots in high-speed continuous drive mode, the DIGIC X processor scans the scene 60 times every second, while simultaneously processing and outputting images at up to 20 frames per second.

Another critical factor in the speed of autofocus is how fast the camera can communicate with the lens, and here the RF mount delivers a new level of performance. By way of comparison, Mike says: "Back in 1987 when we launched the EF lens mount, the communication speed was like walking between the camera and lens. With the Canon EOS-1D X Mark III and a current EF lens, it's more like riding a moped. With the RF mount, it's like being on a bullet train."

A technician wearing white gloves cleans the sensor of a Canon camera.

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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

A groom and five groomsmen of various ages, most wearing sunglasses, walk towards the camera smiling broadly.

Foliage waving in front of the camera, other people in shot, sunglasses, goggles or even a full-face helmet cause no problems for the intelligent face-recognition and tracking abilities of the EOS R5's autofocus. Taken on a Canon EOS R5 with a Canon RF 28-70mm F2L USM lens at 30mm, 1/3200 sec, f/2.2 and ISO100. © Félicia Sisco

Autofocus tracking

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."

Mike explains that with around 6,000 autofocus areas in the Dual Pixel CMOS AF II system in these two cameras, phase-detection points cover virtually the whole frame. The exact number of AF points varies between cameras – in the EOS R3, there are 4,779 covering 100% of the frame. These aren't just looking at what's in focus, but also checking all the defocused areas of the scene. So whereas a conventional system might concentrate on one AF point that's in focus, the Dual Pixel system uses all of the pixels to acquire additional data. It checks defocused objects and how far away they are in the scene. If it senses that a defocused object will cross the path of a focused object, the system can track the movement, work out when the main object will be obscured, and make adjustments to stay locked on.

Adventure photographer and Canon Ambassador Ulla Lohmann has also found the system amazingly effective. "The Canon EOS R5 has let me reimagine the way I shoot," she says. "I was photographing the sunset at a beautiful lake on one occasion and saw a swan, so I tried focus tracking. The focus stayed on the swan even through the reeds. It pushes the boundaries of my creativity."

A common goldeneye swimming towards the camera, reflected in the water below.

The evolution of Canon's Eye Detection AF technology

Discover how Canon developed autofocus technology capable of tracking the eyes of birds in flight, and how this has transformed photography in the field for bird photographer Jonas Classon.
The back screen of the Canon EOS R6 is seen as eye-tracking AF locks on to a woman's eye.

Photographers working across different genres have found the intelligent autofocus in the Canon EOS R6 useful.

Diagram of Canon’s Dual Pixel CMOS AF II technology showing how all pixels are capable of both AF and imaging.

The latest iteration of Canon's Dual Pixel CMOS AF technology means every pixel in the sensor can be used for both imaging and AF, ensuring sharpness right across the frame and enabling an astonishing number of selectable AF points – 5,940 on the EOS R5 and 6,072 on the EOS R6.

Animal subject detection

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."

A close-up of a red and black sports car on a dusty road, a cloud of dust and dirt spraying up behind it.

To enable the EOS R3 to recognise cars and motorcycles, an enormous collection of images of various vehicles was compiled and programmed into the system. "It's really aimed at sports cars and sports bikes," says Mike, "but it recognises most everyday cars as well, as long as they're the same shape as a Formula One car or a standard car." Taken on a Canon EOS R3 with a Canon RF 400mm F2.8L IS USM lens at 1/32000 sec, f/2.8 and ISO400. © Vladimir Rys

Vehicle subject detection

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."

Two flamenco dancers in a courtyard, seen in the display of a Canon EOS R10 with various settings visible.

On the EOS R3, EOS R7 and (as shown here) EOS R10, the AF tracking features can be used in conjunction with any AF area mode, including the new Flexible Zone AF, which allows you to customise the size and shape of the Zone AF area. This means you can target specific areas or zones of the image frame for focusing. You select the zone while the camera selects the particular AF points to use within that zone.

Flexible Zone AF

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."

A close-up of an eye looking into the viewfinder of a Canon EOS R3 camera.

There are three ways to select an AF point when you're using the EOS R3's viewfinder, Mike explains. "There's the Multi-controller which you have on the EOS R5 and EOS R6, the Smart Controller that we introduced on the EOS-1D X Mark III, and Eye Control. The Multi-controller is the most precise because you can move in very small increments across the camera's AF points. But Eye Control allows you to select the subject instantaneously."

A cutaway illustration of the inside of the EOS R3's electronic viewfinder, showing internal components including the OLED panel, eye-focus sensor and LEDs trained at the user's eye.

The Eye Control AF system in the EOS R3 detects where you're looking using an array of infrared LEDs pointed at your eye. The light is reflected into a dedicated sensor matched to the image on the OLED screen, so the camera can determine precisely what you're looking at and which AF points to activate.

Eye Control AF in the EOS R3

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."

A bride and her two young bridesmaids twirl their dresses at sunset on a deserted beach.

This bride's face is comparatively dark in silhouette against the setting sun, but the Canon EOS R5's autofocus system has still locked on instantly. Taken on a Canon EOS R5 with a Canon RF 28-70mm F2L USM lens at 28mm, 1/4000 sec, f/2.5 and ISO200. © Félicia Sisco

Focusing in low light

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

Skrivet av Matthew Richards & Marcus Hawkins


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