Autofocus

The RX100 VI features on-sensor phase detection, which means it can interpret how far away a subject is. This, combined with effective subject recognition make for a fast, powerful combination.

Key takeaways:

  • Autofocus performance is class leading
  • Eye AF can be a 'can't-live-without' feature for some photographers
  • Eye AF begins to fail as light levels drop
  • Autofocus system is complex and multi-layered (and works differently for video)

Autofocus control and setup

The RX100 VI offers five main AF area modes, plus 'Lock-On' versions of them if you shoot in Continuous AF mode. Face Priority, Eye AF and Center Lock-On AF modes all overrule these area choices.

The RX100 VI has a multi-layered AF system. At its most basic you get to choose between single AF and continuous AF but, unlike more expensive models, there are no settings to dictate whether the camera should prioritize focus or shooting speed when you're capturing a burst of images.

There are also a series of AF Area modes that define where the camera focuses:

  • Wide
  • Zone
  • Center
  • Flexible Spot (Large, Medium, Small)
  • Expanded Flexible Spot
  • Lock On Area modes [Tracking versions of each of the above modes]

Wide mode sees the camera picking a subject in the scene, while the others let you be increasingly specific about your chosen subject. The Lock-on versions of each mode are only available in AF-C mode and attempt to track the chosen subject even if it moves around the scene.

On top of these, there are a couple of other AF features that over-ride the AF area mode:

  • Face Priority in AF
  • Eye AF
  • Center Lock-On AF

Face Priority in AF is essentially Face Detection mode (with a Face's effect on exposure metering now defined separately). Center Lock-On AF is a slightly clumsier subject tracking mode. It has to be engaged separately and tries to interpret what it thinks is your subject, until you dismiss it, at which point it'll revert to your previously chosen AF area. We wouldn't recommend its use for stills shooting.

Eye AF

It's Eye AF that's most worth paying attention to. Like Face Detection mode, it will over-ride your chosen AF area (or, at least, consider its input only if it had to choose between which person's eye's to focus on). It's activated by holding down the center button on the back of the camera, at which point it will find and follow your subject's eye with impressive tenacity.

This system works well enough in the a7R III to produce images with perfect focus even with shallow depth-of-field examined at pixel level of 42MP images, so it's no surprise that it works very well for the less demanding RX100 VI. It's reliable enough that you can forget about focus and solely concentrate on composition and interacting with your subject.

Autofocus performance

We build up an understanding of AF performance based on three tests, cross-checked against the experiences we have when shooting other subjects during the review process.

Focus speed

The first is to check how quickly the camera can respond to changes in subject distance, by asking it to refocus on an approaching cyclist.

As you can see, the camera has got all its shots in focus, despite rattling away at 24 frames per second.

Tracking test

The second test expects more of the camera and asks that it identify and track a subject that is moving at a less predictable rate and that moves around the scene in a manner the camera can't predict. This is comparable to a small child running around on a lawn.

It's not intended to be indicative of the challenges of sports shooting, where subjects are likely to be harder to distinguish, both in terms of distance and color.

The RX100 VI shoots with enough depth-of-field at 200mm equiv that it's difficult to assess whether it's perfectly focused but, other than maybe a frame or so where it's mis-judged the change of pace of the rider, as they turn towards the camera, it's hard to conclude that it's missed a shot.

Low-light, close-up test

Finally, we check how well the camera can cope with tracking people in moderate lighting conditions (a scenario we know not to be well represented by the longer distances and brighter lighting conditions of our other testing).

We tested the camera with its 'Face Priority in AF' setting turned on and turned off. When you have 'Face Priority' engaged, the camera will identify the subject's face but then extend the tracking area to include most of the subject's body. The camera then decides where to focus, often simply choosing the nearest part of the subject, rather than the face.

Here's the images from 'Face Priority' engaged.

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Turning Face Priority off means the camera tracks the subject without attempting to identify it and it seems to do a good job, if you watch the video. For a closer inspection, here are the captured out-of-camera images.

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The best results are achieved by holding down the Eye-AF button, though note that, as the light level drops, the camera occasionally struggles to recognize and eye, so reverts to Face Detection mode. Because of the sheer number of images captured, here is a selection of images (one of every ten) taken during this run.

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