Autofocus Evaluation

Out-of-camera JPEG, cropped to taste.
Sony FE 70-200mm F2.8 GM @ 200mm | ISO 320 1/2000 sec | F2.8
Photo by Carey Rose

The Sony a9 on paper has some of the most impressive AF specs we've ever seen: 693 AF points covering 93% of the frame (see what that looks like here), and focus down to -3 EV. Now that we've had plenty of time with a full review unit since Sony's shooting experience at the a9's announcement, we've been able to put it through even more real-world shooting to see how it fares. In many cases, we continue to be impressed with the tracking capabilities of Sony's new flagship, but after thousands and thousands of images captured, we've found the system could still use some tweaking.

Bike test

But first, our bike test. The Sony a9 puts up an extremely good show here, with what is basically a 100% hit rate for the cyclist coming straight at the camera, and a 97%-and-up hit rate for the weave. On one run with the camera in 'release priority,' it did lose focus on our cyclist and shoot to the background for 28 shots (or 1.4 seconds or around 20% of the run, whichever you prefer), but it seemed an isolated incident and the camera refocused on the intended subject before the end of the run.

Here's a rollover of 20 images (one second) during a turn with changing lighting on the subject, which is the most challenging portion of this exercise.

Eye AF for candid photography

Sony's introduction of Eye AF has proven to be a fantastic tool for candid and family photography, and the a9 improves upon it further.

Eye AF is now far more 'sticky' than it was on the a7R II (and other Sony bodies), and more reliable in terms of initial acquisition - place your AF area over your subject, initiate Eye AF, and recompose at will. There's still some occasional jumpiness, but it's come a long long way - particularly when shooting bursts, even at 20fps. We expect Eye AF-C on the a9 will be an invaluable tool for professional wedding, event, candid and newborn photography (it even worked shooting figure skating on the rink), thanks to the reliable results. Take a look for yourself.

Lock-On AF - improved, but still room for improvement

Lock-On AF has certainly been improved over previous Sony cameras, and can certainly be highly effective, as shown with our bicycle demonstration. But it still has a tendency to be somewhat erratic in terms of initial acquisition on a subject, or sometimes loses your subject altogether (though often returns to it eventually, a significant improvement over previous generations). We've put together a brief demonstration of this, as well as how it can manifest itself during burst shooting of fast-moving subjects (see the full bicycle racing take here). In subsequent pages, we'll look at the effect of Lock-on AF's sometimes erratic behavior in real-world sports shooting.

Observations

The a9 takes the best parts of Sony's existing on-sensor phase detection autofocus systems and takes them up a notch. Indeed, without a mirror blocking the autofocus points and with 60 calculations every second, the camera doesn't really need to 'predict' the same way other flagships do; it can just react to the scene in near-real time.

Our bike test, which is still a challenge for many consumer-oriented cameras, shows us that a single subject that is well separated from the background just isn't a problem for the a9. Likewise, Eye AF makes the a9 an (expensive, admittedly) excellent choice for candid photographers at weddings and events.

Let's take a look at how it performs in some additional sports shooting scenarios.