Autofocus
When I first tried a pre-production version of the GH2, in a meeting with Panasonic back in October 2010, I was genuinely excited about the speed of the new contrast-detection AF system. However, I did wonder how it would cope in a real-world test situation.
Thankfully, the new Light Speed contrast-detection AF lives up to its initial promise. Panasonic claims that it snaps from its minimum focus distance to infinity in 0.1 seconds, and while I had no way to accurately test this, after using the GH2 I have no reason to doubt the claim. In AF-S mode, using the 14-140mm f/4-5.8 lens, the camera snaps into focus as fast, if not faster, than most phase-detection systems.
But before you all start selling your DSLRs and buying GH2s, the camera does have a weakness – in single-point continuous AF, contrast detection doesn’t work as well as phase detection and still has to move back and forth to find the point of focus. This slows the focus and causes it to miss the exact area you want, although that is not to say that continuous focus isn’t worth using. The AF tracking and face detection modes work well with moderately moving subjects, so it is more than suitable for use at social events, with children playing and even some sports. If you want to capture faster and less predictable movement, such as a football or rugby match, then a camera with phase-detection AF is still the better option.
Touch AF adds a new dynamic to focusing. It allows you to simply touch the area on screen that you wish to focus on. Even better, though, is the Touch Shutter function. This not only focuses when you touch the screen, but also fires the camera’s shutter and captures an image. The process happens almost instantly, but those concerned that touching the screen will create a slight movement should not worry.
The screen is sensitive enough that it doesn’t require a firm press, and while there is a little more movement compared to pressing the shutter button, unless you are shooting using a telephoto lens or a slow shutter speed you shouldn’t notice any camera shake.
I’m pleased that the AF system of the GH2 lived up to my initial expectations. It goes a long way to proving that contrast-detection AF, when implemented correctly, can be just as fast as phase-detection AF.
It may not be able to keep up with a phase-detection system when it comes to the continuous focusing required for sports photography, but the GH2 really isn’t designed for that type of application.
It’s not just for stills photography that the AF system excels; it also plays a major part in the camera’s video capture capabilities, but more on this later.
