Autofocus

The Leica Q comes with a 49-point contrast-detect autofocus system with options for both single and continuous AF, each including a variety of AF area modes. Considering that this is Leica's first foray into autofocus with a full-frame sensor (the Leica SL came six months afterward), the Q's performance can be very impressive.

As with its controls and handling though, once you dig a little deeper, you'll find some strangeness in the Q's autofocus functionality. Indeed, some settings and modes work very well. Some others, however, notably those that involve the touchscreen, are poorly integrated. Let's take a look at all of that in some detail.

Please note: if this is too lengthy for your tastes, scroll to the bottom for a summary on how best to set up and use the Q's autofocus system.

Single autofocus and continuous autofocus are not the same thing

Before getting to the performance of various modes, the Q's menu settings leave something to be desired. Under the 'Focus' tab, you can select 'S-AF' or 'C-AF.' Beyond that, the subset of modes for each is the same. The problem here is that some of them will work appropriately with either setting, but some modes only function one way - with a single focus acquisition, or continuously.

The main focus menu on the Q. These are the AF modes listed, regardless of whether you are in AFs or AFc.

For example, single-point autofocus works well in either. In Single AF, it will acquire focus once. In Continuous AF, it will continuously focus wherever your selected point is as you or your subject move.

However, let's say you select 'Tracking.' In Continuous AF, it works as you would expect - with good light, it will tend to stick to your selected subject rather well, and will continuously acquire focus whether you or the subject move. But if you select 'Tracking' in Single AF, it exhibits exactly the same behavior. I don't really know what I'd expect, since the idea of 'Tracking' autofocus seems to be pretty much incompatible with the idea of a single acquisition in Single AF, but if that's the case, 'Tracking' should not be an option if you're in Single AF. It smacks of an alarming lack of attention to detail from a camera manufacturer whose reputation involves the opposite.

And speaking of opposites, 'touch-to-focus' and 'touch-and-release' (as in, release the shutter) should not be an option if you're in Continuous AF. In both Single and Continuous AF, they both only acquire focus once, not continuously.

Of course, as you spend time with the camera, you learn and adapt to these issues, but these are things that would bother me if I were shelling out my own hard-earned cash for a product this expensive. It's a bit disconcerting that a casual user could find these issues within minutes of using the camera, when presumably they were coded and implemented over the course of months of development. We're keeping our fingers crossed for a firmware update.

Single autofocus performance

So, let's address the options that, under Single AF, actually work as Single AF.

Remembering that the Leica Q utilizes a contrast-detect-only focus system, single-point single autofocus works incredibly well. Speed and accuracy are excellent under almost any lighting conditions, even with low contrast in a scene. With a fairly wide lens, depth-of-field will usually be fairly deep. Because of this, yes, you can just focus-and-recompose, but the direct access over the placement of the autofocus point with the four-way controller results in speedy adjustments for absolute sharpness. And, with a lens this sharp, you'll certainly notice if your subject is slightly out-of-focus.

In any case, no problems here, even compared to a DSLR with phase detection.

In this image, recycled from our 'On assignment' piece on the Q, I used single-point Single AF, despite the fact that I had moving subjects. However, the AF was so fast that it wasn't really a problem. Photo by Carey Rose, processed and cropped to taste from Raw. F2 | 1/125 sec | ISO 2500

Multipoint single autofocus works quickly and accurately as well, selecting a number of objects in a scene on which to acquire focus.

Face detection Single Autofocus does a good job of identifying and focusing on faces quickly. However, if any of your subjects turns away slightly, the camera isn't adept enough to recognize individuals' profiles as 'faces.' The 'background' mode seems to be multi-point, so if you have multiple faces in a scene, you don't have any reticle on-screen to select a face with. This method of face detection is arguably less valuable than on Sony cameras, for example, where face detection can be enabled as an add-on with any area mode. So on a Sony system, it's possible to utilize face detect in single-point mode, and use that single-point to select the face on which to focus.

Touch AF works well with the touchscreen, allowing you to poke directly where you want the Q to acquire focus, which it promptly does. The problem is that, should you just want to use the touchscreen just for ease of autofocus placement, you cannot force the camera to reacquire focus at that point with a half-press of the shutter. You must touch the screen again to force the camera to reacquire focus. Additionally, if you raise the camera to your eye to use the EVF and want to change the position of the autofocus point, both the touchscreen and the four-way controller are disabled and won't move the point. For obvious reasons, this behavior is really annoying, and so Touch AF is actually best avoided for most shooting scenarios.

Touch and release, oddly, doesn't exhibit exactly the same behavior. It focuses where you touch, then snaps a photo, and if you half-press the shutter, it does reacquire focus on the spot where you touched. As with Touch-AF, though, you can't fine-tune the autofocus point location with the four-way controller, or with the screen if you have the camera to your eye. You have to touch-and-release again. Another mode best avoided, unless of course you're shooting from an odd angle that makes the shutter button difficult to reach.

Continuous autofocus performance

Now for the continuous AF modes that are actually continuous.

Single-point continuous autofocus works reliably, and very well. If you can keep your autofocus point over your subject (which may compromise your composition), the camera will have no problem keeping up with a moving subject. As is typical of CDAF systems, there is incessant hunting if your subject isn't moving. Take a look at the rollover below.

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Multi-point continuous autofocus exhibits the same behavior, but is somewhat less usable. After showing where it has acquired focus with a number of green AF-point boxes on-screen, the boxes will disappear and the Q will continue focusing and hunting - but you can't really tell what it's focusing on anymore without the on-screen boxes. Is there one point its favoring over others? Beats me.

Face detection continuous autofocus works with the same caveats as in Single AF, only now it will be hunting back and forth before you hit the shutter and it locks down focus.

Given good light levels, the tracking option sticks to a subject with tenacity, but has trouble keeping up with rapid movement. It's best suited to single-shot modes rather than continuous drive, and in fact, is a better option even than face detection in our view. Place your point over an individual's face, and because it uses fairly robust scene analysis to track, it will stick to that face even if an individual turns mostly away.

Summary and setup

The sum of all these findings is a fairly simple one. With the camera in its current state (firmware updates could conceivably improve upon most of the performance findings here), it's best to keep the camera in Single AF and either single-point or multipoint configurations, depending on your taste. Our preference is to use single-point and use the four-way controller to move the autofocus point around. In this configuration the Leica Q is so fast and so responsive that, unless you're shooting fast-moving and erratic subjects, you probably won't miss continuous autofocus at all. We usually didn't.