Autofocus

Among the myriad improvements Panasonic has claimed regarding the GH5 is continuous autofocus performance; capable of 9fps with autofocus and autoexposure, the GH5 may likewise appeal to users who are looking for both a high-end, action video (180fps full HD video standing out for this particularly) and action photography camera in one package. But Panasonic continues to use a contrast-detect-only system, although their Depth-from-Defocus (DFD) technology makes it one of the best contrast-detect performers on the market. Let's see how it did.

Bike test

As we've come to expect from Panasonic's DFD technology, single-point AF-C performs well. What this basically translates to is that if you are comfortable choosing an autofocus point and following the action yourself, the GH5 should perform admirably, though the viewfinder resolution drops precipitously at the highest burst rates (lag, at least, is well controlled).

One thing to note about DFD, though, is that the very nature of how it works (very rapidly 'wobbling' the focus element back and forth to constantly ensure peak sharpness) means that, peppered throughout your bursts, you will inevitably have images that aren't quite tack-sharp, but aren't unusably soft. For anything but critical usage though, the results should be acceptable.

It's the GH5's tracking autofocus performance that we're most interested in, however. We've seen in previous Panasonic's that the tracking can be quite 'sticky' in live view, but can often be tripped-up when attempting to track while shooting bursts, or can sometimes throw a 'red box' and refuse to initiate tracking at all. But it's evident that Panasonic is tacking this Tracking AF seriously, as it's added custom presets of three different autofocus parameters to tailor the camera to whatever you're shooting.

Panasonic's description of this system and its recommended settings are somewhat at odds with one another, which made it difficult to configure, but here's what we've been told:

Autofocus parameters:

  • AF Sensitivity: This is a measure of how willing the camera is to make changes in the focus depth. The higher, responsive values mean the camera is willing to make substantial focus changes. The lower settings means the camera delays before making a significant focus depth change.
  • AF Area Switching Sensitivity: This adjusts how readily the camera will switch away from what it thinks is the subject (ie: is something entering the frame to be ignored or should it be considered the new subject).
  • Moving object prediction: This adjusts the degree to which the camera tries to anticipate changes in speed / direction of your subject, depending on the predictability of its motion (think auto racing versus soccer).

Let's see how it works at default, 'Set 1,' which is the 'basic setting' suitable for a wide range of subjects, according to the manual. The above parameters are set to 0, 0 and +1 respectively.

Over a number of runs, the GH5 puts out about a 60% hit rate, which isn't high enough to be reliable for crucial situations in our opinion. As shown in the example above, the camera would sometimes lose Richard completely for some time before reacquiring him, and this happened often. We should note, though, that the GH5 did very well at the closer end of the run, which is where many competitors tend to struggle. In any case, with all the custom options available, we were able to try a few other options out to see how they performed, and we were able to get much better results with some customization.

We shot around 500 images using variations on Setting 4 (with default parameters of 0, +1 and +2), which is 'for subjects that change speed and move unpredictably.' We experimented with further tweaking of the parameters, and bumped the hit rate up to roughly 85%; in other words, we cut the percentage of out-of-focus images in half. And the number of images were unacceptably out of focus were drastically reduced (far fewer of them in a row, as seen above). The moral of the story here is clear; take some time to learn how best to set up the camera for what you're shooting.

For reference, we had best results with the bike test by starting with Set 4 and boosting 'Switching Sensitivity' to +2, though Set 4 at its defaults was the next-best performer. The above rollover takes things a step further with all settings 'maxed out' at '+2, +2, +2' as it showed the most representative run from all the various settings we tried.

Interestingly, Panasonic USA's recommended settings are essentially opposite of this. Despite extensive discussion and further testing, we've not managed to get any better results. The whole thing is not helped by the way the camera describes the settings (note in the video the suggestion that moving the settings away from 'responsive' will make the camera more responsive). Despite scouring the manual, consulting with Panasonic tech experts and extensive testing, we would not confidently expect to be able to correctly configure this camera for a given shooting situation, so expect considerable trial and error and a perpetual nagging doubt that the camera might be able to perform better.

Close up test

For this test, we used low-ish light levels with mixed color temperatures with multiple subjects who may be moving somewhat unpredictably; in other words, we're attempting to mimic a casual social interaction where you may want to use autofocus tracking to capture just the right moment, instead of manually moving the AF point around (which you can't do on the GH5 while subject tracking through the viewfinder, although you can tap to initiate tracking on a subject if using the flip-out screen.

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We used 'Set 4' for this test, since there is a lack of predictability with photographing individuals in a candid setting, and it worked well overall. The camera would occasionally lose the subjects, but initial acquisition is fairly fast (once you've 'cancelled' any previous attempt at tracking - more on that later), and the general 'stickiness' of the tracking is impressive.

Having established a pretty solid performance in two everyday shooting situations, let's see how the GH5 fares in the much more chaotic, challenging case of trying to shoot a rugby match.