Autofocus

Raw image converted using Adobe Camera Raw. Highlights reduced, blacks increased.
Nikkor 24mm F1.8 |ISO 100 | 1/50 sec | F16
Photo: Richard Butler

The Z50's autofocus system is closely related to that of Nikon's high-end Z6 and Z7 models. Overall we found it to be generally good, but both the performance and the interface behavior are not quite up to the standards of the best of its peers, or that of Nikon's best DSLRs.

Key Takeaways:

  • Autofocus is fast and generally very effective but subject tracking can drift off subject
  • Face/Eye AF works well at fairly close distances and lets you choose between subjects
  • Subject tracking is poorly integrated compared to rivals (and Nikon's own DSLRs), requires that you toggle in/out of the mode

The AF system

The Z50's basic autofocus system is pretty straightforward: you can choose an AF area size or 'Auto-area' where the camera chooses a subject based on how close and central it is.

  • Pinpoint AF (AF-S only)
  • Single-point AF
  • Dynamic-area AF (AF-C only)
  • Wide-area AF (S)
  • Wide-area AF (L)
  • Auto-area AF

The finest AF area mode (pinpoint) is only available in single AF acquisition mode, and continuous AF mode gains the 'Dynamic-area' mode, which considers the AF areas adjacent to the chosen point, for when you're trying to keep the camera pointed at a moving subject.

The four-way controller on the back of the camera is used to move the AF point, or you can tap the touchscreen, if you've got that mode activated. What you can't do is swipe or tap the screen when you've got the camera to your eye: a feature of many modern cameras, including some Nikon DSLRs.

Face/Eye Detection

The Z50 has a Face or Face/Eye detection system. It acts on top of 'Auto-area' mode. If you've got Face or Eye detection turned on, the camera will prioritize this over other subjects. If more than one face is found, then tapping left or right on the four-way controller lets you select which to focus on.

However, there are a number of limitations. Firstly, your subject needs to be pretty large in the frame before the camera will identify it as a face. Secondly, there's no persistence: if you select one subject but they turn away or something obscures their face for a moment, the camera will jump to focusing on any other face in the scene and you'll have to wait for it to re-find your chosen subject before you can re-select it.

Perhaps because it's only recently been added to Nikon's cameras, you cannot directly assign Face/Eye detection to a button, nor to the camera's 'i' menu. However, you can hack round this by setting it as the top option on the 'My Menu' list, and then assigning a button to 'Access top item in MY MENU.'

Subject tracking

Like Face/Eye detection, the Z50's subject tracking system is only available in Auto-area mode, and again over-rides the Auto-area function. To start tracking, you either need to tap the rear screen or press 'OK' to engage the mode, adding an extra step, compared with most of its peers.

On the occasions that the tracking gets confused and finds its own subject, you have to press 'OK' again to reset the point, rather than just releasing the shutter button. This resets the focus reticle to the center of the screen (not wherever you'd set it to, previously). If you want to disengage the tracking mode, you'll have to find and press the Zoom-out 'button' on the right edge of the screen (this is difficult when the camera is to your eye, since there's no physical indication of where the button is).

Performance

AF Testing conducted using an adapted an F-mount AF-S Nikkor 70-200mm F2.8 G IS.

Central AF point

AF Tracking mode

Our first test uses a central AF point on an approaching subject and tests the ability of the camera to assess subject distance and drive the lens to it. The Z50 does very well in this respect.

We then test the AF tracking mode, which requires the camera to identify and follow the subject as it moves around the scene (in addition to assessing distance and driving the lens to the correct point). The Z50 also does very well here: many cameras mis-judge the subject distance to the bike as it slows and accelerates through the corners. However, we conduct this test a number of times for each mode and, just as in our non-test shooting, there was an instance in which the camera stopped following the subject and tracking something in the background, instead.

From observing the occasions the camera does lose its target and starts tracking something else, we suspect the system is slightly too heavily based on identifying subject color and isn't taking subject distance into account, to a big enough degree (it will sometimes refocus onto things at radically different distances, if they're a similar color).

Overall

The performance of the Z50's AF system is rather good; it will fairly reliably focus on the thing you've asked it to focus on (aside from tracking mode occasionally drifting off and taking an interest in something else). It's also a little slower than most of its peers at refocusing to a different distance if you change subject, but rarely to a problematic degree.

However, much of the way you interact with the AF system seems poorly thought-out, giving a slower experience than we've come to expect in the latest mirrorless cameras and requiring more frequent changing of modes and settings. This isn't a show-stopper by any means, it's just not as slick as it could be.

The performance of the Z50's AF system is rather good but the interface seems poorly thought-out

Other cameras let you access Face Detection regardless of which AF mode you're in and make it easier to cancel or over-ride, so you don't have to completely change your setup to access the feature. Other cameras also make better use of their touchscreens, in terms of selecting AF points, and it's becoming pretty-much standard to let you use your chosen AF point as the starting point for AF tracking (just as you can on Nikon's DSLRs), rather than having to engage/disengage a special mode from one particular AF area mode.

Each of this complaints amounts to a fairly small gripe, but each aspect slows down the user, limiting your ability to respond in-the-moment and meaning you have to stop to change setting, depending on what you're shooting, more than you do with its peers.