Take a new look at Canon's Eye Control AF

How Canon's revolutionary Eye Control AF technology has evolved to give you intuitive, fast and responsive autofocus control in the EOS R3 and beyond.
A man wearing warm clothing, a woolly hat and glasses stands at the edge of a sports pitch holding a Canon EOS R3 with super-telephoto lens to his eye, supporting the weight of the lens with his left hand.

The Canon EOS R3's Eye Control AF system works in any of the camera's AF selection modes, but is especially valuable when used in conjunction with Subject Tracking. Sports photographer and Canon Ambassador Łukasz Skwiot found it very fast and effective when selecting between players on the football pitch. "A typical example is where you have several players in the frame and want to follow one of them," he explains. "All you have to do is look at the one you want, and the camera will focus on that player and track him even if other players appear from the side or come between the player and the camera. Problem solved!" © Krzysztof Basel

The Canon EOS R3 introduced a host of technical innovations, but one of the most talked-about of these was a refinement of a revolutionary technology from the past: Eye Control Autofocus. Originally developed 30 years ago, Eye Control AF enables the camera to set or switch the autofocus point by detecting what you're looking at in the viewfinder. In the EOS R3, the technology has been reimagined for a new generation of cameras.

It's important to bear in mind the difference between Eye Control and Eye Detection/Tracking – the two autofocus technologies work together, as we'll see, but they are distinct from each other. A number of Canon EOS DSLR and mirrorless cameras include Eye Detection and Tracking AF, enabling them to lock on to the eyes of human and animal subjects and keep them in focus, but as of mid-2022 only the EOS R3 has Eye Control AF, which monitors the photographer's eye to set or move the autofocus point.

Here, we delve into the development of Eye Control AF, speak to Canon Europe Senior Product Specialist Mike Burnhill about the innovations behind the current technology and how Canon engineers refined its accuracy, and discover how professionals such as sports photographer Łukasz Skwiot are using it to capture sharp shots of decisive moments.

A view of two racing motorbikes through the viewfinder, with an orange circle and AF frame on the front bike.

Using Eye Control AF to acquire the subject to track: the camera detects where the photographer is looking (the orange circle) and sets the AF point. With the EOS R3's Vehicle Tracking AF, the camera can then keep the focus on the fast-moving bike.

A view of two racing motorbikes through the viewfinder, with an orange circle and blue rectangle outlined on the rear bike.

To switch subjects, the photographer presses the shutter button halfway to activate Eye Control again, then looks at the new subject. The blue frame indicates the new AF point, and the focus instantly shifts to the bike on the right.

The history of Eye Control AF

The original version of Eye Control was implemented in the Canon EOS 5 in 1992, then included in a few other 35mm film SLRs and camcorders. It attracted a lot of attention, but the technology at that time was still fraught with challenges – accuracy varied from person to person, some users experienced eye strain, and slight eye movement during shooting sometimes caused the focus to shift or blur. As digital SLRs emerged and features such as multi-controllers were added to cameras, Eye Control AF technology was shelved for the time being.

"But once we got to the latest generation of mirrorless cameras, the opportunity became available to implement the technology again," explains Mike. "With mirrorless, there was a leap in technology that provided the autofocus accuracy, positioning and fluidity that was needed for Eye Control AF."

Early DSLRs had a very limited number of AF points – nine in the case of the EOS 5D, released in 2005, for example – and these were mainly confined to the centre of the frame. The size of the AF point array has been greatly expanded with successive generations of EOS cameras, and the EOS-1D X Mark III, an advanced professional DSLR released in February 2020, has 191 selectable AF points. However, the breakthrough EOS R mirrorless camera, introduced in October 2018, has 5,655 AF points, covering 100% of the frame vertically and 88% horizontally. Full-screen autofocus was finally achieved in July 2020 with the EOS R5, which has 5,940 AF points covering the entire screen. Now it is possible to track subjects no matter where on the screen they appear.

Having such extensive coverage, however, can make it more challenging to manually select an autofocus point quickly. "With mirrorless cameras, the number of AF points has increased and the coverage of the area has increased as well," says Mike. "So being able to go from one side to the other is a bit of an issue, because there's a lot of steps between the two. The return of Eye Control AF is an ideal solution, because with eye control, you can literally move the AF point from A to C without going to B."

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Evolving accuracy

Naturally the technology behind Eye Control AF has evolved far beyond the original version. When Eye Control AF was introduced in the Canon EOS 5, a single infrared sensor was used to track the movement of the photographer's eye. But the EOS R3 system features eight infrared LEDs at different angles. "Not all of them are used simultaneously," Mike explains. "The sensors are used for different purposes, depending on things like how close your eye is or whether they detect that you're wearing glasses.

"There's also a small imaging sensor inside the viewfinder. So the infrared light shines into your eye and illuminates the back of your eyeball, and then it bounces back to this sensor, which creates a retina scan. The sensor has a direct relationship to the image on the high-resolution OLED screen in the electronic viewfinder, so it knows which area of the image the eye is looking at and which AF points this corresponds to on the main imaging sensor."

Of course, if the camera is going to focus with precision, it needs to know precisely where you're looking. That's why calibration is key when it comes to accurate Eye Control AF. With the original system there was only one calibration, but with the EOS R3's Eye Control AF it's possible to refine the calibration.

"The problem is that the shape of the human eye changes a lot," says Mike. "When you move from a dark location to a bright one, for example, or when you rotate the camera from vertical to horizontal, the eye can look very different. So one of the biggest changes in the EOS R3's version of the Eye Control AF system is its ability to rebuild its algorithm for the calibration, to refine it. So the more you do it, the better it gets."

That said, you don't have to calibrate Eye Control AF every time you pick up the camera, Mike adds. "But we recommend that when you first get the camera, you calibrate it in different ways. Use it in the different orientations that you're going to use it in and how you'd use it, indoors and outdoors, on a dull day and a sunny day, and so on."

Six distinct Eye Control AF calibrations can be saved to the camera. "If you wear glasses, the distance from your eye might be different compared to if you were wearing contact lenses, so it's worth saving separate settings," Mike suggests. "You can even save them to a memory card, so you only have to calibrate the setting in one camera and then you can load it into other bodies."

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.

In the EOS R3's electronic viewfinder, paired with the high-resolution OLED panel (numbered 1), there is a dedicated eye-focus sensor (2), which processes eye-position data and matches it to the image on the OLED panel. The user's eye is tracked using an array of LEDs emitting infrared light at different wavelengths and different angles, including some designed for eyeglass-detection (3) and some for naked-eye detection (4).

A small black box with screws at the corners has a round bulge at the front, looking like an eyeball with a pupil in the middle.

The artificial eyeball created by Canon's developers for use in trials of the Eye Control AF technology.

Testing and perfecting

It's not just the shape of a photographer's eye in different situations that the Eye Control AF system has to accommodate. Whether it's the thickness of eyelids, length of eyelashes or other such features, no two people's eyes are the same. Glasses can further complicate matters, and even the different ways in which photographers hold their cameras mean that the distance between the eye and the camera viewfinder differs from person to person.

To address such issues, Canon recruited hundreds of testers to assess its technology under challenging conditions. Developers even went so far as to create an artificial eyeball for use in trials. Canon's medical division was also consulted.

"We make a lot of medical measuring devices," says Mike. "Opticians can use our retina scanning technology to check the health of your eye, for example. So the medical division provided information that helped us to refine this technology. This is a division that's really developed during the interim period between the EOS 5 and the EOS R3. So with the EOS R3, everything coalesced. We had the technology, and we had even more knowledge of how to use it."

In addition, members of the team who were involved in the original development of Eye Control AF all those years ago are still with Canon, and they were able to offer their experience and insight.

"One of the developers who worked on the original system is now the head engineer and is in charge of the design division," reveals Mike, "and there are people who worked in the early stages who are now managers and division directors. So it's nice for them to come full circle, and be able to bring back technology that they spent some time working on as a junior, albeit now in a much more complete form."

Photographer Vladimir Rys looks through the viewfinder of a Canon EOS R3 with a long lens attached.

Using the Canon EOS R3's amazing Eye Control AF

Find out all about this great feature of the Canon EOS R3 and how it can set or switch the AF point by detecting what you're looking at.
Two young taekwondo practitioners wearing padded helmets spar with foam-rubber staffs, with others seated on the floor in the background out of focus.

Once Łukasz had used the Eye Control AF system to focus on one taekwondo competitor's face, the camera's AI-powered Face Tracking algorithm was able to keep the selected competitor's head in focus even though it was concealed by a helmet and sometimes obscured by the other competitor, and even when other, often more easily recognised faces were in shot. Taken on a Canon EOS R3 with a Canon RF 70-200mm F2.8L IS USM lens at 1/500 sec, f/2.8 and ISO2500. © Łukasz Skwiot

Three footballers in red tops are on a field. The one in the middle has just kicked a ball and is in focus, the two either side are out of focus.

Łukasz used Eye Control AF when shooting a football match and the warmup before it. "If you have several players at different distances from the camera or on either side of the frame, all you have to do is look at the one you want to be sharp," he says. Taken on a Canon EOS R3 with a Canon EF 400 mm f/2.8L IS III USM lens at 1/1250 sec, f/2.8 and ISO2000. © Łukasz Skwiot

Using Eye Control AF

The EOS R3's Eye Control AF doesn't require you to constantly keep your eye focused on the subject. "Eye Control AF has been designed to work alongside the camera's subject detection functionality," says Mike. "And they're the perfect combination.

"For example, say you're faced with five actors on a red carpet. Who is the most important person to focus on? Obviously the human brain is very good at recognising and identifying people, and Eye Control AF gives you an intuitive way to communicate that to the camera.

"Once the system knows which person you want to focus on, it can lock on to their eye or their face, and it can track them as they move. If you want to choose someone else, you can instruct the camera to check where you're looking, and the camera will switch focus. So it's a quick initial decision, and then you can let the camera do all of the hard, precision work for you."

In the hands of professionals

Eye Control AF has obvious benefits where speed is crucial, such as news and wedding photography. Action photographer Vladimir Rys put it to the test on his first electric rally car shoot, where he found it greatly sped up the process of selecting between multiple possible subjects. He used it together with the EOS R3's groundbreaking Vehicle Tracking AF, which locked on to the subject he identified and stayed focused on it as long as he wanted.

Canon cameras support multiple AF selection methods, so you can use the touchscreen to tap the area you want to focus on, as well as move the AF point using the multi-controller. But nothing is faster and more intuitive than simply looking at the subject you want.

"When photographing sports, especially professional ones, we often have a fraction of a second for the correct focus – otherwise we will miss the decisive moment," says sports photographer Łukasz Skwiot. For him, there's "no comparison" in speed between Eye Control AF and other ways of selecting an autofocus point. "I use the Canon EOS-1D X Mark III's Smart Controller on a daily basis, and that allows me to change AF points very quickly," he says. "But it's not as fast as Eye Control AF on the EOS R3."

At a football match, Łukasz says, "all I had to do was look at the face of the football player I wanted to focus on and, with Eye Detection enabled, the camera would focus precisely on the player's eyes. Likewise, when I was photographing taekwondo – the heavily padded helmets posed no problem for the system." When he photographed two taekwondo practitioners training side-by-side, once he had selected one of them using Eye Control AF, the Eye Tracking continued to follow the selected subject even when the other person was closer to the camera and occasionally obscured the selected subject's face.

"Some people said Eye Control AF was just a marketing gimmick that will not work in practice," Łukasz concludes. "After testing it, I have a completely different opinion. This is a truly useful feature, and I love it."

Marcus Hawkins

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