Real-world Autofocus Performance: Soccer

Since the D5 effectively aced our motorized, airborne version of the Richard Butler Man on a Bike Test™, it was time for another sport. Enter soccer (football for the rest of the world). For this particular match, we had low-ish light, dark blue jerseys that blended into the background, and as always with soccer, various players criss-crossing and moving in wholly unpredictable ways. 

Ouch. Processed and cropped to taste from Raw. Photo by Carey Rose. Nikon AF-S 300mm F4 PF @ F4 | 1/800 sec | ISO 12800

A quick trip to the Nikon Professional Services Global site reveals Nikon's suggested setup for shooting the world's most popular sport. They identify using 25-point dynamic-area continuous autofocus (for nearly everything, curiously), also going so far as to specify the 'blocked shot AF response' value to be 2 and 'subject motion' to be normal. Noticeably absent from any of the sports listed on that page is Nikon's 3D Tracking mode. So, since I personally use 3D Tracking for just about everything and because it worked so well for motocross, I decided to try both it and Nikon's recommendation. Let's start with the oddball choice: 3D Tracking.

Note - rollovers on this page are made from Nikon ViewNX-i screen captures, and have been cropped to allow for easy identification of the AF point. They are not representative of the D5's image quality.

3D Tracking

With soccer, the D5's 3D Tracking performance far exceeded my expectations. I used slightly different settings than Nikon's recommendation for Dynamic-area, setting 'Blocked shot AF response' to 3 and subject movement to 'erratic.' With that setup, if I successfully initiated autofocus on my subject, the camera tracked impressively well, keeping the point over the subject as they moved around the frame. Even during bursts, which is not necessarily my experience with lower end, non-Dx series bodies like the D810. This let me follow my subjects a little less carefully than if I was following them with a manually picked point, and also freed up my compositions a little bit. What's most surprising, though, is how tenaciously 3D Tracking would stick to my subject when it was completely blocked by another player. It remembers.

1 2 3 4 5 6 7 8 9 10

My experience largely mirrored that of our Tech Editor, Rishi, who despite it being his first rugby game ever, came back with an enormous number of hits simply using 3D Tracking to specify his subject, then firing away while following, somewhat imprecisely he'd add, erratically moving players at 300mm.

But that's not say that 3D Tracking is completely infallible. When the camera loses the subject, you may find yourself re-framing and re-initiating quickly, but luckily the D5 is really quick at that re-initiating part (focus acquisition is fast). Sometimes though, you just end up with this:

1 2 3 4 5 6 7 8 9 10

Admittedly, in the above images, 3D Tracking had a lot working against it. A dark subject, backlit, on a dark background. In any case, you can see how the camera decided to start tracking the player closer to the camera (possibly anticipating movement of the existing subject, possibly influenced by the backlighting), rendering the original subject out-of-focus by the time he decided to kick the ball. 

So there's the rub. Despite how well 3D Tracking works, it is fallible in certain situations. It also does slow down, and get more inaccurate, in lower light. And let's just say for the sake of argument that the above play was a crucial one, and all I came back with was a shot with missed focus. That's not good. That's where 25-point dynamic area autofocus might come in handy.

Dynamic-area autofocus

As described on our main autofocus page, dynamic-area autofocus heavily weights a single, user-selected point surrounded with 'helper' points. The idea is that you, the photographer, track the action yourself, and the helper points analyze either a portion of the scene or the entire scene to provide some leeway if you let your point slip off a subject for a short while.* As long as you can follow the action, it works remarkably well, but behaves quite differently from 3D Tracking. Here's an example.

1 2 3 4 5 6 7 8 9 10

In this sequence of images, I chose to simply stay with the center point (note that Nikon's software doesn't show you the 'helper' points surrounding it). You can clearly see how, when dialed into Nikon's suggested settings, 25-point dynamic-area autofocus works just as expected. Instead of trying to track the initial subject through the foreground player, it simply reacquires focus rapidly when that player's body takes up the entire 'dynamic area,' then refocuses rapidly back again when the action emerges from behind him. Of course, whether or not it will refocus this rapidly depends on your 'Blocked Shot AF Response' value, which in this case, was fairly short at '2.' What's more, with these settings, this behavior was repeatable and predictable throughout the time I used this mode.

It's worth reinforcing that with a larger dynamic area and slower 'Blocked Shot AF Response' value dialed in, the camera's behavior will change accordingly - it may not refocus as rapidly or readily on a new subject blocking the intended subject. It's really up to you, the photographer, to find a starting point, and dial in any changes as you might need them.

The takeaway

If you are a full-time sports photographer that knows the sport you're shooting inside-and-out, there's little reason to give up control to the camera via 3D Tracking mode. Although we've seen how it's very good, a seasoned pro will be able to follow the action just as well and the autofocus system should be able to keep up, so long as your custom parameters are dialed in properly.

But 3D Tracking has its place. It still works exceptionally well as a default, go-to mode for general shooting. It's great for weddings and events, allowing you more compositional freedom. As an example, you might have a great angle of view and shot framed up for the bride walking down the aisle. With dynamic-area or single-point AF, you'd have to place a focus point on the bride and follow her, thereby ruining the composition you'd already picked out. You can also avoid pre-focusing and having to stop down to get you additional depth of field. With 3D Tracking, you can frame everything up, initiate tracking on her and continually focus as she moves through your chosen scene.

And that's the great thing about having all of these modes - once you're familiar with them, you can choose which modes work best for your style of photography. 

Processed and cropped to taste. Photo by Carey Rose. Nikon AF-S 300mm F4 PF @ F4 | 1/800 sec | ISO 12800

Flicker

If you've noticed some weird color shifting on the rollovers above (particularly on the grass), it's not your eyes, it's the pulsing of the fluorescent lighting. Despite the Nikon D500 having a fairly effective 'flicker reduction' feature, it has been omitted on the D5. 


* How long the camera will track your subject if it falls off the main, selected AF point in a dynamic mode, before simply refocusing to whatever currently lies under the selected AF point, is determined by 'Blocked shot AF response' (the higher this value, the longer before the camera refocuses).