Autofocus Tracking

The 5D Mark IV's revamped autofocus system, being so similar to that of the 1D X Mark II, should be able to track moving subjects extremely well, whether through the viewfinder, or in Live View thanks to its Dual Pixel autofocus technology. Whether we pointed the Mark IV at Dan on a bicycle, or an excited and erratically moving dog, or utilized face detection for more candid photos, the camera performed admirably, but with a couple caveats.

This very-low-light image came out properly focused courtesy of Dual Pixel AF in Live View. Canon EF 35mm F2 IS USM, ISO 32,000, F2.0, 1/200 sec.

Photo by Dan Bracaglia

The Bike Test

For our standard bike test, we used the Canon EOS 5D Mark IV in Case 1, which is suggested as a versatile set of parameters for a variety of subjects - and for the most part, it didn't disappoint.

Single point focus

When you stick to your subject with a single point just for depth tracking, the hit rate is very nearly 100%.

iTR focus tracking

When you switch to iTR tracking, however, the hit rate drops, but not so much as to render the setting unhelpful, particularly if you're in an unfamiliar situation where you may not be able to follow the movement of your subject. And indeed, the 'misses' with iTR are slight enough to be fairly insignificant at normal viewing sizes.

Dual Pixel AF Tracking

Using Dual Pixel AF in continuous shooting also netted a high number of keepers, showing some advantage to this new system over our previous experience with the EOS 80D. Unfortunately, despite the increased effectiveness of the system, it is arguably a less useful feature on the 5D Mark IV than on its APS-C cousin, due to the fixed screen. This limits your ability to use the touchscreen to track subjects and fire off bursts when working at odd angles - say holding it above your head to track subjects at a wedding reception, for example.

And something else to keep in mind - as you 'tap' your subject, the tracking box will grow or shrink as it decides what exactly to track. It would vary from just Dan's head to most of Dan's upper body. As such, if you find you need more fine control over exactly where you need the camera to autofocus, you may have better luck using a single point through the viewfinder.

But as is the nature with any autofocus system, particularly during subject tracking, Dual Pixel AF not infallible. Check out how the camera confused Dan's ride with a slightly less environmentally conscious mode of transportation.

Here, we watched as the tracking 'box' strayed off of Dan and onto the similarly colored Prius as it drove behind him. Focus did not return to Dan until we re-tapped to acquire him as a 'new' subject.

The Dog Test

To test an even more erratically moving subject than our two-wheeled Dan Bracaglia, we headed to Gas Works Park in Seattle with a friend and a very playful pooch named Mamook.

Despite weaving movements and rapid acceleration and deceleration, the 5D Mark IV performed well in its default Case 1 AF mode when shooting through the viewfinder with iTR enabled.

Though iTR has lots of potential, you have to be careful - for a following burst with my initial point over the pup, the AF system got distracted by the grass and Mamook was never in focus until we stopped focusing and re-acquired later on.

iTR and Dual Pixel Face Detection

Face detection can be enabled for both viewfinder and Live View shooting, and for candid shooting at events and the like, it works remarkably well. Couple this with the fact that you can assign iTR functionality through the viewfinder to a simple press of the AF-ON button while keeping your shutter button active for, say, Single Point AF, and you've got a pretty versatile setup.

Unfortunately, as we've found with Canon's other iTR implementations, it simply isn't as accurate as we've found some of its competitors' systems, such as Sony's Eye AF, and Nikon's 3D Tracking, which will effectively track an eye if you initiate autofocus on it. Note, in the below video, the system isn't fooled by any other distracting elements (or other distant faces) in the scene, but the points float around Sam's face, sometimes focusing on his eye, and sometimes other parts of his face resulting in some slight mis-focus.

Face detection and tracking in Live View, though, is a different story, as you can see on our Video page. Importantly, face detection in Live View stills shooting focuses accurately on the plane of the face, meaning the eyes are more likely to be in critical focus than previous Canon cameras (and you can always stop down a bit). Some of those older implementations would achieve focus on the front-most portion of a face they detected, which was usually the tip of the nose, rendering the eyes almost consistently out of focus.

The wrap

The 5D Mark IV's autofocus system is extremely similar to the 1D X Mark II's system in terms of speed, function and reliability. This means that, for some more trying situations that what we've seen here, you may find yourself tweaking your AF Case modes, and making sure that you use the appropriate AF Selection Area.

In other words, when changing from shooting static subjects to moving ones, we found ourselves switching from 'Pinpoint AF' in One Shot (single-acquisition AF in Canon vernacular), to 'Single Point AF' or 'AF Expansion' for the area mode and a change to AI Servo (continuous AF in Canon-speak). Doing so netted a higher number of images in critical focus than trying to use one set of global parameters for everything.

Now that may seem like a natural and obvious conclusion to most of you. But we have gotten to try out Nikon's latest implementations of 3D Tracking for everything from portraits to sports, and it's a system that doesn't really require a change from AF-S to AF-C or a change in area modes. In turn, this frees the mind up a bit more to focus on what we're shooting. Will the Canon net a similar number of keepers in the hands of someone who knows what settings to use and when? Of course. But this continues to be a fundamental difference between these two professional systems.