Editor’s note: please keep in mind that the topics discussed here primarily reference EOS R-series models introduced after the original EOS R and RP models… the first EOS mirrorless models may have some of these capabilities, but models such as the EOS R6 and R5, and those Canon EOS mirrorless models launched afterward, incorporate many more of the technologies and capabilities discussed here. Not every EOS mirrorless model will have each of these AF features, as of 2025.
Perhaps nowhere are the advances for photographers using mirrorless cameras more evident than with autofocus. The possibilities of modern mirrorless cameras have transformed the way photographers take pictures. Technology has truly come to lend a giant helping hand to photographers, even in the most challenging conditions. If you are a DSLR user, regardless of whether you work with an entry-level DSLR model or a high-end camera, consider the points we explain in this article as you think about the benefits of stepping up to a mirrorless Canon EOS R-series camera.
AF Coverage of the Picture Area
With digital SLRs, you worked with a number of pre-set focus points, permanently arranged around the central area of your viewfinder. While over time, the number of SLR focus points progressed from a single point in the center up to over 60 AF points (with cameras like the EOS 5D Mark IV or EOS 7D Mark II), there was always a fundamental design issue: AF points in DSLRs never covered anywhere near the full picture area.
A depiction of the 61 AF points in an EOS 5D-series DSLR, vs. the coverage of nearly 100% of the picture area with mirrorless cameras. Modern mid-range and high-end EOS mirrorless cameras, in fact, extend the horizontal range to virtually 100% of the width of the frame — more than is illustrated in this illustration.
With modern mirrorless cameras, photographers are liberated. Whether using a single AF point or AF Area, or a larger AF detection area, users are free to either:
- Move a single AF Area over nearly the entire frame
- Activate the entire picture area (or nearly the entire picture area, on some models) and allow the camera to automatically locate and focus upon subjects essentially anywhere in the frame
Compositions like this are simple with mirrorless cameras, whether you rely on the camera automatically putting focus upon an off-center primary subject, or you manually move an AF Area to the far edges of the frame. With DSLRs, this would often require locking focus and then re-composing the camera.
The effect of this is truly liberating, when a mirrorless camera is in your hands. Whether you shoot portraits, weddings and events, wildlife and action images, or macro images, you can simply compose and shoot in one movement, no matter where your subject is in the frame. There’s rarely a need to lock focus and re-compose with mirrorless cameras — although of course you’re free to do that as well.
AF Area — the Size of What the Camera Focuses Upon
Photographers had the ability to gather multiple AF points to form a larger “cluster” of points for autofocus, with DSLR cameras like the EOS 7D models, or the EOS 5D Mark III and Mark IV models. And, within the boundaries of where AF points were located, these expanded AF areas could be manually moved to some degree.
But today’s Canon EOS R-series models allow a multitude of choices in where the AF system detects focus in a scene, ranging from Spot AF (a single, relatively small AF point) through Flexible Zone AF (three user-defined area choices, which can easily be re-sized, broadened or narrowed using camera controls). And, there’s Whole Area AF (on some models, it’s called “Face Detect + Tracking”), which makes 90%–100% of the picture area open for focus detection.
Again, the flexibility is incredible. Users who prefer to work carefully, using a single AF point, can easily do so, with the comfort of knowing they can manually move that AF point over essentially the entire frame. And users who want to work quickly and have the camera identify a subject and place focus upon it — even focusing on the eye of a detected human or animal subject — can do so, over nearly the entire frame. To repeat, the need to lock focus and re-compose is drastically reduced.
Eye Detection and Subject Detection
Perhaps nowhere else is the difference between traditional digital SLR cameras and mirrorless models more vivid. Mirrorless design has opened up incredible autofocus performance, with cameras able to identify subjects such as humans, common animals (typically birds, cats, dogs, and sometimes horses — depending on the camera model), and vehicles. The camera can immediately pick such a subject from an entire scene, and immediately place a focus box around it in the viewfinder or the LCD screen.
Whether posed or in motion, photographing portraits, events, street images, and more are a joy with the Eye Detect AF and Subject Detect AF in mirrorless cameras. With AF Area set to Whole Area AF (“Face Detect + Tracking” on some models), just compose off-center and the subject — and its prominent eye — are immediately highlighted in your viewfinder or LCD screen the instant the AF activation button is pressed.
And with humans or compatible animal subjects, the user can have the camera identify a subject’s eyes, and place a much smaller AF point directly upon that eye. No longer are photographers required to move the camera to put an AF point on a subject’s eye, re-compose, and hope in the meantime that the subject doesn’t move.
Animal Subject Detect AF and Eye Detect AF can transform your abilities and results in wildlife and nature shots. Animal Detection can put focus upon an animal’s head or body, but with Eye Detect AF also active, AF can be concentrated upon a detected eye, even with moving subjects like birds in flight.
Focus Tracking Can Change How You Compose and Shoot Pictures
The ability to detect a subject, or even its eye, and immediately focus upon that part of the subject would be remarkable if it was limited to stationary subjects only. But it’s not.
With today’s mirrorless cameras, a detected subject can be continually followed around the entire focusing area (that means nearly 100% of the frame, if “Whole Area AF” is active), whether the camera moves, or the subject moves. This is focus tracking — the ability to move the AF area being used over the entire frame, whether up, down, left or right. With Servo AF active, you likewise have ability to focus on subjects moving toward or away from the camera. All that’s required is to start AF, and keep the AF activation button active as you follow your subject.
Focus Tracking with mirrorless cameras can be a tremendous aid in situations beyond sports and action. Even a studio or portrait photographer can use this, along with Servo AF, to put initial focus on a model’s face or eye, and then freely re-compose… Focus Tracking will maintain constant focus upon the subject and follow it, as it moves around the frame. All that’s required is to maintain pressure on whichever button is activating autofocus, with Servo AF active.
A wedding or event photographer can seamlessly adjust composition and zoom, all the while maintaining sharp focus upon the eye or face of their primary subject. A wildlife photographer can focus upon the body or even eyes of a moving animal, up to and including a bird in flight — with constant Servo AF. A macro photographer can manually move a single AF point once, to put initial focus upon a subject, and then freely move the camera to change his or her compositions, while Servo AF and Focus Tracking keep the same part of a subject in-focus, at different locations in the frame.
Welcome to the world of mirrorless cameras, and mirrorless photography.
Low-light AF: A Win for Mirrorless
Not only is the Electronic Viewfinder a huge asset at low light levels, but the AF of modern mirrorless cameras typically offers noticeably greater low-light sensitivity than was common with digital SLRs. While there remain limits as to how dark a scene can be and still permit mirrorless cameras to autofocus, in almost all cases low-light limits are expanded with mirrorless AF. Enhanced low-light viewing and focusing is a win-win situation for mirrorless camera users.
Servo AF Performance
Previously called “AI Servo AF” on Canon’s SLR cameras, Servo AF in modern mirrorless cameras functions the same way. It keeps the AF system focus continually upon moving subjects, or keep focus detection “live” if the photographer simply moves the camera around the frame. This isn’t just an asset for sports photographers; we’ve already mentioned how even a portrait or wedding photographer can maintain continuous focus upon a subject’s face or even eye, while the photographer changes composition or even changes focal length with a zoom lens.
In modern mirrorless cameras, Servo AF performance is often simply superior in comparison to what most previous DSLRs could offer, especially with challenging, fast-moving subjects. And, it can be a big asset even situations like street photography, weddings and events, and other situations, where getting the shot quickly is the photographer’s goal.
Servo AF is even better on many modern mirrorless cameras than it was with most previous digital SLRs. One example of the night-and-day focusing difference of mirrorless vs. DSLRs is the number of tack-sharp images you can find today — from mirrorless cameras — of subjects like birds in flight, which were supremely difficult to focus upon with digital SLRs. Many of today’s top professional sports and wildlife photographers are fully invested in mirrorless cameras and this update in AF technology. Digital SLRs could be quite good in this area, but there’s no question that mirrorless has moved the proverbial needle.
One other Servo AF benefit, that long-time Canon EOS users will appreciate — in some higher-end EOS camera models, the various “AF Cases” to optimize Servo AF to different types of subject movement have been greatly simplified. Mirrorless EOS models have the processing speed to recognize different types of motion when set for Servo AF, and actually perform such Servo AF adjustments automatically. In those cameras, the older, user-applied “Cases” are now greatly simplified — while Servo AF performance is boosted. It’s a win-win for photographers.
Progress Doesn’t Stop: New AF Technology Advancements
In Canon’s latest mirrorless cameras, specifically the EOS R5 Mark II and top-of-the-line EOS R1 (both launched in mid-2024), even more has been added to the AF capabilities:
- Register – Recall AF Settings
A menu option to store different combinations of AF settings, and then immediately recall them on the camera’s magenta-colored AF Menu. Photographers shooting different types of moving wildlife, or other types of action, can quickly switch from AF settings optimized for one type of subject or situation to settings that are tailored for another. - Register People Priority
Modern mirrorless cameras do all AF calculations and light metering directly off the CMOS imaging sensor, and not via separate, dedicated AF sensors as was the case during viewfinder shooting with SLR cameras. With greatly enhanced pixel resolution (vs. previous, separate AF-only sensors), some high-end EOS models can now actually recognize individual people, and immediately put focus upon them, even if other people are also in the scene. Shoot one test image of up to ten different subjects, “register” them in the AF Menu under “Register People Priority,” and when the camera sees that bride, VIP, or whomever in the frame, it immediately focuses upon them — without intervention from the photographer, and even if there are other faces in the frame. - Action Priority
This is an incredible technological advance, for certain types of sports photography (keep in mind, as of 2025, it is for still images only). There are Menu selections for Soccer, Basketball or Volleyball. Once activated, the camera can recognize specific actions and movements particular to that sport, and instantly put focus upon an athlete performing them. For example, photographing basketball, things like a player beginning to dribble toward the camera, passing, shooting or rebounding will prompt an immediate AF box around that athlete. Particularly when a user is composing with multiple players in a single shot, this can really optimize their shot selection. And the great Servo AF and Focus Tracking you’d normally expect continue to function.
Summary
AF evolved over time in previous digital SLRs to a point where the vast majority of users felt it was “good enough” for their needs, and no one at Canon is suggesting a user is wrong to continue to use a digital SLR. But the advancements users will experience if they make the investment into a modern EOS R-series mirrorless camera can be stunning. And that applies even for those who feel they rarely if ever shoot fast-moving action. Portrait photographers in the studio can benefit. Event and wedding photographers will absolutely benefit. The bottom line is better pictures, leveraging superior outstanding AF technology. If you still use a digital SLR, we strongly suggest at least taking a “test drive” with a modern mirrorless camera, and seeing the capabilities for yourself.
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