Autofocus

We're excited for sporting events to be making a comeback in the near future, but in the meantime, we've made do. Cropped out of camera JPEG.
ISO 100 | 1/8000 sec | F1.8 | Sony FE 135mm F1.8 GM
Photo by Chris Niccolls

The autofocus system in the Sony a1 is one of the best that we've seen, with tenacious tracking of subjects of all kinds, including human faces and eyes, as well as the eyes of birds and other animals.

Key takeaways:

  • Sony's 'Real-time Tracking' seamlessly transitions from generic subject tracking to face and eye tracking and back again, as appropriate
  • Autofocus points cover approximately 92% of the frame
  • Be sure to manually select between human, animal and bird eye-detection
  • Produces nearly a 100% hit-rate in our testing
  • Low light sensitivity has increased 1 EV over a9 & a7R IV, now reliably focusing down to -4 EV

System overview

The Sony a1's autofocus system will be familiar to those who have used recent Sony cameras since the introduction of their latest subject tracking interface, which the company calls 'Real-time Tracking.'

The updated menus make it easy to immediately find all of the AF settings you might need.

In essence, with tracking enabled, the camera will tenaciously track objects of all kinds; if your subject happens to be a human or recognizable animal or bird, the camera can automatically transition to eye detection. If it loses recognition of your subject's eye, or your subject turns away, it will revert back to generic tracking where the eye was last seen (i.e., your intended subject).

The overall reliability of this tracking means that, frankly, many people could set up their AF system once and never need to worry about it again save for edge cases. Because of this, though, we do think that Sony could perhaps simplify some of their AF Area modes; 'Center', for example, does nothing more or less than any of the 'Flexible Spot' modes when the flexible spot is placed in the center of the frame.

From left to right, Wide, Zone, Center, Flexible Spots S, M and L, and 'Expand Flexible Spot' area modes. The top row comprises the non-tracking versions, while the bottom row lists the tracking versions. There's a lot in here, but at least you can hide which ones you cycle through if you only use a handful.

As for us, we tend to use Tracking: Flexible Spot M for most of our shooting. This allows you to use the joystick to place an AF area over your chosen subject, and a half-press of the shutter (or AF-On button) initiates tracking of that subject. Release the shutter or AF-On button and the AF area returns to where you had previously placed it.

For general shooting and in our testing, we found the default settings yielded excellent results. But the AF response is customizable if you find yourself photographing a subject with more specific needs that trip the system up.

Customization options are fairly straightforward; you can set the camera to: prioritize the release of the shutter when you press it even if the lens hasn't quite achieved accurate focus; wait for the lens to achieve absolute accurate focus; or leave it up to the camera in 'Balanced Emphasis' as seen above. AF Tracking Sensitivity adjusts how readily the camera will jump to a new subject if something (an opposing team's player, perhaps) gets between you and your initial subject.

And depending on your shooting situation, you may find it helpful to change the color of the AF area to red over the default white.

Animal and bird Eye AF

Bird Eye AF is honestly pretty handy for an amateur birder in the backyard. Plus, 50MP gives lots of room for cropping, which you may find you want to do, even with 600mm of reach. This is a heavily cropped image is still around 12MP.
ISO 2000 | 1/320 sec | F6.3 | Sony 200-600mm F5.6-6.3 G OSS @ 600mm

As mentioned earlier, the Sony a1 offers Eye AF of some animals and birds, and for some casual backyard birding, we found it worked impressively well. One thing to be aware of though is, unlike Canon's EOS R5 for example, you must select which subject you want to prioritize.

Canon's system allows you to set 'no priority,' and it would still recognize birds reliably. Once you select the 'Bird' option here, the Sony a1 performs really impressively, but once you're done birding and off to a portrait session, you'll need to remember to switch this option back to 'Human'.

Autofocus performance

The Sony a1's autofocus tracking is nearly faultless, even with fast movement, close subjects and wide apertures.
ISO 100 | 1/500 sec | F1.2 | Sony FE 50mm F1.2 GM
Photo by Rishi Sanyal

Sony tells us that the combination of the new sensor and processor allow for a whopping 120 autofocus / autoexposure calculations every second, even while shooting burst at 30fps. That's twice what the a9 / a9 II could manage, even at its slower maximum burst speed of 20fps. So what does that look like? Let's take a peek.

To check AF performance, we first use a single, central AF point with a subject approaching in a straight line. This checks how well the camera is able to assess the distance of the approaching subject and focus accordingly. We tested this using both the mechanical and electronic shutters using the FE 70-200mm F2.8 GM. For a single approaching subject, the Sony a1 turned in effectively a 100% hit rate.

The more challenging test comes next. We switched the camera into its 'Tracking: Flexible Spot M' mode, to see how well it can identify and follow a selected subject as it weaves unpredictably (for the camera) around the frame, in addition to re-focusing. The camera was set to prioritize human subjects, and AF Tracking Sensitivity was set to the default setting of 3.

Rounding a turn as shown here shows the most challenging aspect of our test, and the Sony a1 consistently turned in impressive results. Out of the more than 1000 images we shot, around 2% were just slightly out-of-focus, with only a handful soft enough to be what we might consider approaching unusably out-of-focus.

We also noticed that, when Dan was masked up, the system would reliably track his head through the run as a generic object; when we removed the mask (and remained distant), the camera would recognize his face and eyes throughout much of the run.

Finally, we performed the same tests with the fully mechanical shutter at its maximum rate of 10fps and also observed a near-100% hit rate.

Low-light AF performance

Sony says the a1 will focus down to -4EV with an F2.0 lens, a 1 EV improvement over the a9/II and a7R IV which Sony claim to focus down to -3 EV. Indeed, we found the a1 will continue to use phase- and face-detect AF confidently down to roughly -4 EV in our test environment, an improvement over the a7R IV which reverted to contrast-detect AF at around -2 EV under similar conditions. At around -2 EV conditions, the a1 shot tack sharp photos while the a7R IV shot mostly out-of-focus ones:

1/250s | F1.4 | Sony FE 35mm F1.4 GM

The light levels pictured above represent approximately -2 EV. The a7R IV resorted to CDAF, resulting in many out-of-focus images, while the a1 confidently detected the face and focused reliably using PDAF.

Links to full-resolution images: a1 | a7R IV

As light levels dropped further and the a7R IV gave up entirely, the a1 continued to use phase-detect AF, focusing without hunting down to -4 EV to yield images such as this one. Under these conditions, there was the occasional mis-focused image, but the majority of pictures were in focus. While we don’t have a direct comparison here, it's worth noting that in our general experience the a9 / II cameras focus more reliably under low light conditions than the a7R IV, so we don't wish to generalize the performance of the a7R IV here to all previous gen Sony cameras. Note our quoted EV values are approximate.