We were already impressed with the Sony a9 when we reviewed it, giving it a score that put it on par with its two very capable rivals, the Nikon D5 and the Canon EOS-1DX II. In April this year, nearly two years after the camera's launch, Sony introduced a significant firmware update that largely revamped the autofocus system of the camera, adding a new 'real-time tracking' AF mode that works seamlessly with face and eye detection. Sony also updated face and eye detection algorithms by using machine learning to understand human subjects and features more accurately.

We've spent some time shooting with the updated a9 in a variety of situations, and have previously written and in-depth look into what the new AF system brings. After further testing, we've re-scored the a9 with the boosted autofocus in mind, and it brings the score up to 90% (from 89%). This makes the a9 the highest-scoring camera in its class, out-ranking the Nikon D5 and Canon EOS-1D X II.

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The increased score reflects the precision of the updated a9's subject tracking system, as well as its ease-of-use that makes it valuable for nearly all types of photography. Click 'Read our review' above to jump to our full review (originally published in 2017), and read on for a description of the new real-time tracking mode, with some examples and videos of the system in use.

Real-time tracking in use

'Real-time tracking' refers to the ability of the a9 (and a6400) to understand the subject you initiated focus on, and track it in three dimensions, much like 3D Tracking on Nikon DSLRs, and the respective subject tracking modes on various mirrorless cameras. What sets the a9's system apart are both its performance (we found it to reliable enough to be useful for portrait, event, candid, sports and even landscape photography), and its ease-of-use.

To pick a target, you can simply reframe your composition to place your AF point over your subject, half-press the shutter, and real-time tracking will collect color, brightness, pattern, distance, face and eye information about your subject so it can use it to keep track of your subject.

It's robust enough that it will even, again reliably, switch in and out of Eye AF as necessary if a face or eye is detected on the subject you are tracking, as you can see in the video above.* Collectively, this means you can concentrate on the composition and the moment. There is no longer a need to focus (pun intended) on keeping your AF point over your subject, which for years has constrained composition and made it difficult to maintain focus on erratic subjects.

In practice, the system excels. While many professional sports photographers that know their sport, and can anticipate the action, have successfully used Single Point or Zone AF for years, real-time tracking can help both the amateur and the pro achieve potentially better results. First, it frees up the photographer to compose freely, as composition is no longer constrained by having to keep an AF point over the subject. But perhaps more importantly, not having to keep a fixed AF point or zone over a fast moving subject is a boon when it comes to fast, erratic subjects shot using long telephoto lenses, where framing is increasingly difficult. The sequences below were shot with the 600mm F4 GM lens at a soccer match (click on any thumbnail to launch the gallery):

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Unpredictable motion combined with a 600mm focal length makes it difficult to keep a fixed AF area over your subject. Here, real-time tracking tracked our players even as others passed in front of them, switching in and out of Eye AF, and reverting to generic subject tracking, as necessary so as to not lose the original subject. Photos by Barney Britton

And below, despite erratic motion, changing directions, and nearby similarly-dressed players, the camera tracks the original player in both instances. In the first sequence we targeted the player in red (Everton); in the second, the player in silver (Ivan). Only one or two shots in the sequence are slightly misfocused.

If you'd like to take a look at another sports sequence, click here to jump to our footnote. Away from sports and burst photography, we found the performance of Sony's 'real-time tracking' to be beneficial for even more stationary subjects, as it frees you up to try different poses and framings quickly, as we've done below.

Most of the 20 shots above were captured in under 19 seconds, without ever letting off the AF-ON button. The camera never lost our model, and the seamless transitioning between Eye AF and general subject tracking allowed the AF system to remain on our subject throughout the series. By not having to think about focus, you can work faster, and come home with a greater variety of images to choose from.

*This video demonstrates 'real-time tracking' on the a6400, but the principle is the same on the a9.

** Another sequence of images showing the a9's real-time tracking mode following a player (Besler, in red) despite numerous distractions (click any thumbnail to launch the gallery):

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