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Eye Control AF explained

Get the inside story on Canon's amazing Eye Control AF system, which sets or switches the AF point by detecting what you're looking at.

Eye Control AF explained

A male photographer looks through the viewfinder of a Canon EOS R3 with a long lens attached.

Action photographer Vladimir Rys put the new features of the Canon EOS R3, including Eye Control AF, to the test on his first electric rally car shoot.

Fast, precise autofocusing paired with subject detection and tracking mean it's easier than ever to get a sharp shot of a moving subject using a Canon EOS camera. However, the decision to switch from one subject to another still rests with the photographer, and the process of recognising that there's a new, more interesting subject, then using your thumb to shift the focus point, can result in a slight delay that means a key moment could be missed.

Imagine, for example, that a cheetah going in for a kill suddenly comes under attack from a lion, or the favourite in a race pulls up short, or a protestor interrupts a political statement – these are all unexpected events that demand a shift in the photographer's attention and a change to the focus point. The first few moments are crucial to telling the story and it's essential that the focus switches quickly to the new subject. With the Canon EOS R3's Eye Control AF it's possible to switch between subjects just by looking where you want to focus in the viewfinder, rather than reaching for the Multi-controller and nudging the AF point across.


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A man stands on an elevated gantry with a camera raised to his eye, pointing it down at a red rally car on the ground.

As the Canon EOS R3's subject detection and tracking takes care of the focusing, the photographer can concentrate on the composition and watch out for new potential subjects entering the frame.

A cutaway illustration of the inside of the EOS R3's viewfinder, showing internal components including LEDs trained at the user's eye.

The innovative technology inside the EOS R3's viewfinder includes LEDs trained at the user's eye and a specialised sensor for acquiring images of that eye.

History and development

If Eye Control AF sounds familiar, that may be because Canon introduced a similar technology with the Canon EOS 5, a semi-professional 35mm film camera released in November 1992. That feature was later seen in the EOS 50 (1995), EOS 3 (1998) and EOS 30 (2000). However, things have evolved since then.

Since that time Canon's Medical Systems division, which specialises in medical imaging, has developed a range of technologies for scanning eyes to produce Purkinje images. Like a fingerprint for eyes, these images enable doctors and opticians to diagnose problems, but the information gained has also given Canon's Photo Division a better understanding of what eyes look like. In turn, this has informed the development of Eye Control AF.
Canon's original Eye Control AF system used just one light, but inside the Canon EOS R3's viewfinder there are eight LEDs, which emit different wavelengths of infrared light. Using a variety of light sources at different angles enables the system to function even if the user is wearing glasses or contact lenses.

In addition, the detection system has much higher resolution than in the past – there's a 7,560-pixel scanner dedicated to acquiring Purkinje images of the eye. These images enable the camera to understand the position of the user's eye and the direction it's looking in.
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A woman in a black and white racing suit stands holding her helmet, long hair blowing in the wind. A red rally car is behind her, out of focus.

Eye Control AF enables the focus to switch in an instant, so if a new target appears behind the current subject, you can select it. Taken on a Canon EOS R3 with a Canon RF 50mm F1.2L USM lens at 1/10,000 sec, f/1.2 and ISO50. © Vladimir Rys

How Eye Control AF works

A key point to understand about Eye Control AF is that it doesn't require the eye to look at a subject and follow it in the viewfinder to get the camera's focus system to stay with it. Human eyes don't work that way – we scan and look around the scene constantly, and if the AF point were to track that movement, the focus would continually jump around the frame.

Instead, Eye Control AF is designed to work in tandem with the Canon EOS R3's subject tracking, and it's used to select the subject to be tracked at the outset. Once that's been done, there's no need to stare at the subject – the camera takes control of tracking it and focusing as it moves.
"Think of using Eye Control AF like the mouse or cursor of a computer," explains Mike Burnhill, Canon Europe Professional Imaging Product Specialist. "You use it to click on your subject and then let the camera's software do its job."

This means that although the Canon EOS R3 has 4,779 AF points, you don't need to try to look at one particular point. Instead, just look towards the subject generally and the camera will use its hierarchical method of subject detection to focus on it. So when Subject Detection is set to Human in the menu, the subject's eyes are prioritised. If they're not visible, it will look for a human head, and if it can't distinguish that, then the body is prioritised.
A red rally car captured at speed, kicking up a cloud of dust behind it.

Going off-road with EOS R3

Motorsports photographer Vladimir Rys tries out the EOS R3's groundbreaking racing car tracking AF on his first electric rally car shoot.
A dirty red rally car races across the image, kicking up a cloud of dust behind it, in front of an out-of-focus mountainous background.

The Eye Control AF system works in any of the AF point selection modes, but really proves its value in conjunction with Subject Tracking. The EOS R3's groundbreaking Vehicle Tracking AF makes it easy to keep the focus on even a fast-moving car. But that's not all... Taken on a Canon EOS R3 with a Canon RF 50mm F1.2L USM lens at 1/32,000 sec, f/1.2 and ISO1250. © Vladimir Rys

The back of a red rally car is seen at the very left of the shot, exiting the frame. The car is still in focus, and the mountain background to the picture is blurred.

Because the Dual Pixel CMOS AF system covers the entire sensor, the Canon EOS R3 can track subjects right to the edges of the frame without the focus switching to the background. Taken on a Canon EOS R3 with a Canon RF 50mm F1.2L USM lens at 1/32,000 sec, f/1.2 and ISO1250. © Vladimir Rys

Using Eye Control AF

Getting started

"Eye Control AF isn't active by default," Mike explains, "but it can be activated by pressing the Set button. Then, when you press the shutter button halfway, if there are eyes or faces in the scene you'll see a grey box around them. Look at the one you want to target to select it, then press the shutter button down fully. The box will turn blue and the camera will follow the subject." If you're in continuous shooting mode, the camera will track the subject until you release the shutter button.

To switch subject, you just need to release the button, then half-press and look at the new subject before pressing the shutter button fully again.

Part of the tool kit

Although Eye Control AF works in any of the AF point selection modes, Mike recommends using it with Subject Tracking and using the Smart controller or Multi-controller to select very precise areas in single-AF mode.
A close-up of a man's eye at the viewfinder of a Canon EOS R3.

To get the best from the Eye Control AF system, you need to calibrate it. You can train it for up to six different users or different eyewear.

Customising the system

There are three ways to customise the Eye Control AF. The first and most important task is to calibrate it to your eyes and any eyewear you use while shooting (see below). Each set of eyewear needs a separate calibration, and you need to ensure you use the correct setting when you change glasses.

It's also possible to customise a button for activating Eye Control AF. There are numerous buttons available, but Mike suggests that the AF-On button is a logical choice as many photographers already use back-button focusing.

Finally, any of the autofocus and Eye Control AF options in the menu can be assigned to My Menu. If you frequently change your glasses, or take them on and off during shooting, this is a good way of accessing the user settings quickly.

Eye Control AF options

There are two shapes available for the Eye Control AF pointer (or cursor): a circle or a reticule. The circle can be orange, purple or white, so you can set it to a colour that stands out from the scene, Mike explains, "while the reticule is useful when you want to see small details of the subject because it covers a smaller area."
A red rally car drives towards the camera, entering the shot from the left in front of a steep hill.

With the Subject Detection set to Vehicles, the Canon EOS R3 is quick to recognise a car in the frame, focusing on it while the photographer takes care of the composition and timing of the shot. Taken on a Canon EOS R3 with a Canon RF 400mm F2.8L IS USM lens at 1/5000 sec, f/2.8 and ISO3200. © Vladimir Rys

Calibrating Eye Control AF

"It's important to calibrate the Eye Control AF to get the best from it," says Mike. "You can calibrate it for up to six different users or six different setups, such as with and without glasses or contact lenses, or different types of glasses, for example." Each user or use setting can be named, so you know exactly who or which spectacles it's for.

"When it's activated," Mike continues, "the calibration system shows a dot in the viewfinder. You have to confirm that you're looking at it, then it will move, and you need to follow it with your eye. This needs to be done with the camera in horizontal and vertical orientation, both inside and outside, but you don't have to do it all at once. You can come back to a calibration."

Although the basic calibration only requires four runs through, it can be refined by repeating the process in different locations and with the camera at different angles. It's a groundbreaking feature that gives photographers a powerful tool for capturing fast-moving action in a variety of scenarios.

Autorius Angela Nicholson


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