Autofocus

Autofocus has previously been something of a weak point for Fujifilm. The X-T2 improved things and was very good at single AF and could be good at subject tracking if the subject was well isolated from the background. The X-T3 improves just about every respect.

Key Takeaways

  • X-T3 is fairly fast to focus and, with some configuration, can be effective at subject tracking.
  • Face / Eye detection can be very useful but gives no way to select whose face you want it to focus on.
  • Like many on-sensor PDAF cameras, it can struggle in back-lit circumstances.

The X-T3 offers four AF area modes: Single Point, Zone, Wide/Tracking and All (which is essentially an easy way to cycle between the other three). On top of this, the camera offers Face and Eye detection options, which we're told have had their algorithms completely re-written.

ISO 500 | 1/250sec | F5.6 | Fujinon XF 55-200m F3.5-4.8R
Photo: Carey Rose

AF-C fine tuning

Like the X-T2, the X-T3 has the ability to fine-tune the behavior of the autofocus system to match the behavior of your subject. This works in both Wide/Tracking and Zone modes. There are five preset 'use-cases' and sixth setting that lets you further tailor the response if one of these use-cases isn't quite delivering the results you want.

For this custom mode, you are given control over three parameters:

  • Tracking sensitivity defines how long the camera waits before refocusing if there's a sudden change in distance to the subject, which lets you choose whether to focus on subjects that suddenly appear or avoid the camera getting distracted by obstacles that temporarily get in the way.
  • Speed Tracking Sensitivity tells the camera how predictable the movement of the subject is likely to be (a constant rate or accelerating/decelerating).
  • Finally, Zone Area Switching defines whether the camera gives priority to the object at the center of the chosen focus zone or the closest object within the zone, with an Auto option that prioritizes the first thing focused on.

Broadly speaking, you need to consider how responsive you want the camera to be and how predictable the movement of your subject is, when choosing or configuring a preset.

Face/Eye Detection

The X-T3's Face Detection system has been completely re-worked and, in conjunction with the camera's greater processing power and phase-detection coverage, is now a much more powerful prospect (it used to be the first thing we disabled on Fujifilm cameras due to excessive hunting). However, it's still not as good as the best of its peers.

Face Detection completely over-rides the underlying AF system

The X-T3 is good at finding faces (though you'll get the odd false-positive, where it thinks there's a face in an everyday object) and, if you've asked it to, will focus on the left, right or auto-selected eye.

Eye detection AF meant I could concentrate on framing and my subject, rather than having to think about positioning the focus point.
Fujinon XF 50-140mm F2.8 R LM OIS WR | ISO 160 | 1/420sec | F2.8

It's not always instant and will sometimes briefly lose a face if the subject turns too far away, so it's not quite as good as Sony's uncanny Eye-AF system (which is excellent at recognizing eyes, even if they're only briefly visible). It's still very useful though, especially for posed portraits, where it'll deliver the kinds of consistency and precision that DSLRs can struggle with. It means you can focus on your framing and your interactions with your subject, rather than having to think about where your AF point is.

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Face Detection does a good job at focusing on faces, but there's no control over which one (it'll automatically prioritize the face nearest the center of the scene). If it temporarily 'loses' a face, the focus will jump off to a different person.

Face Detection completely over-rides the underlying AF system though. As such, there's no way of specifying which face you wish to focus on: it ignores any selected AF point and prioritizes the face nearest the center of the frame. This can be a problem as it can briefly 'lose' one face and jump to another. It also means that the camera will prioritize a face, even if you've asked it to track something else. And, because there are multiple options for Face and Eye detection, you can't simply toggle it on and off with a button press.

Continuous Autofocus

To test continuous AF performance, we first try to shoot a subject approaching at a steady speed using the central AF point. This lets us see how good the camera is at assessing subject distance and whether it can drive its lens to that point quickly.

AF-C Mode 1
AF-C Custom Mode

We then have the subject weave across the camera's AF region in a way the camera can't predict. This has the advantage that the approach rate varies as the subject changes direction. For this test we use the camera's subject tracking mode, so it needs to identify and follow a subject around the scene, as well as trying to keep it in focus.

At its default settings, the X-T3 did pretty well at following the subject, but could lose the subject as it changed its approach speed on the corners. We then adjusted the fine-tune settings, creating a variant of the camera's Preset 5 for an "erratically moving and accelerating/decelerating subject," but telling the camera to prioritize the closest subject. This performed better, with only slight mis-focus as the cyclist slows and changes direction.

In both modes, we found the camera would occasionally completely lose the subject if it immediately veered off the focus point at the start of the run, so it seems to help the camera if you can keep the focus point over the subject initially, to help the camera establish its target. This, of course, isn't an issue when using Zone mode and keeping the camera pointed at your subject.

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We had a similar experience in our lower-light test, which is designed to mimic social situations. Set to Preset 5, the camera does a good job of staying on the correct subject and of keeping focus on it. Furthermore, using the subject tracking mode (Wide/Tracking) with Face Detection turned off allowed us to choose which face to target.

Overall performance

Nikon's D500 holds onto its crown as the most sports-capable APS-C camera on the market, since the X-T3 isn't quite as responsive. The Fujifilm is now a much closer second, though. And, thanks to improved Face/Eye detection, is probably faster and more precise at focusing for posed portraiture. There's still a degree of lens dependency (some of Fujifilm's early and large-aperture lenses aren't as fast to focus as the more modern, linear motor designs), and occasional mis-focus in back-lit conditions, but the range of circumstances in which the X-T3 can be configured to get you the shot has been significantly widened.

These AF improvements make the X-T3 a much more flexible camera. Probably on a par with the Sony a6500 in most situations, but arguably easier to configure and use.