Autofocus
With full-area touch AF, picking out the point of focus is easy. The grass is less than 2m away and the heron well over 20m, yet the focus is very rapid
One of the main benefits of the 120fps sensor readout is that communication with the lens is faster, resulting in what the company claims is a 0.09sec AF response. Focusing is achieved via the shutter release or the touchscreen, and both are equally responsive. Those sceptical about a touchscreen should try the Lumix DMC-GX1.
During this test, I decided the erratic and ultra-fast movement of birds as they took flight was a good subject for the AF response. The 20fps mode and 0.09sec AF and shutter lag meant that sequences not possible with slower systems were captured by the GX1. Generally, when the shot was missed it was my own reactions (and not the camera) that failed to keep pace.
As with metering, the user can select anywhere in the frame for the AF point. Once again, I found this resulted in my using spot AF rather than multi-area AF more than usual.
There are several AF modes, including face detection, tracking, 23-area, 1-area (spot) and pinpoint. In the latter mode, once the user has touched the screen for the AF point, focal magnification helps to indicate the point of focus. For manual focusing there is an MF assist at 4x, 5x or 10x magnification.
Tracking AF is particularly helpful when shooting videos, by and large giving a smooth, non-distracting focus. For still images in low light the system is impressively responsive for closer subjects, thanks largely to the powerful AF assist lamp.
For scenes of frenetic movement like sport and wildlife, the contrast-detection system does not cope as well overall as the phase-detection systems found in expensive DSLRs, but I would not expect it to. Instead, the GX1 is ideal for general use.
