Performance

The GH4 is generally a very fast camera. Whether in terms of the viewfinder's response times or the immediacy of settings changes and menus opening, the camera always makes it feel like your actions are having direct effect.

Continuous Shooting and Buffering

The GH4 is rated as being able to shoot at 12 frames per second without live view or focus. We found that, certainly for JPEG shooting, it could comfortably achieve this.

Timing
Large/Fine JPEG
Raw
Raw+Fine JPEG
Frame rate 13.4 fps 11.6 fps 10 fps
Number of frames 144 shots 35 shots 35 shots
Buffer full rate 3 fps 1.9 fps 1.6 fps
Write complete 20 secs 23 secs 37 secs

It's worth noting that additional processing options, such as the camera's iDynamic mode, will reduce the maximum shooting speed.

Autofocus

Panasonic has made a lot of its 'Depth from Defocus' system, which uses profiles detailing the out-of-focus behavior of its lenses to assess the subject distance even when they're not in focus. The advantage of this system is that it doesn't require any modification of the underlying hardware, which can very occasionally have an impact on image quality. The most obvious disadvantage of the system is that the camera requires a profile of the lens being used and these are currently only included for Panasonic's own lenses.

This example was shot using the Panasonic X Vario 12-35mm F2.8.

Frame 1
Frame 2
Frame 3
Frame 4
Frame 5
Frame 6
Frame 7
Frame 8

These eight frames come from a sequence shot using a custom area autofocus selection - a horizontal stripe that excludes the furthest right-hand point, to prevent the camera getting distracted by by the tree on the right.

The camera does a pretty good job of re-focusing on a moving subject. Sadly we couldn't get the camera to lock onto the rider as a subject, which meant we weren't able to properly test the camera's focus tracking. As you can see, the DFD focus does a good job of correctly following the subject distance.

When we tested the focus tracking in the video section of this review we found that it could be difficult to get the camera to consistently recognise a subject, meaning that it couldn't then track that subject. The same proved to be true of our (admittedly single-scenario) cycling-towards-the-camera examples.

After repeated attempts (including setting the subject with the rider close to the camera, then backing up, to retain the subject-lock), we couldn't get the camera to reliably lock or stay locked onto the subject. However, specifying a series of focus points and letting the camera prioritize the subject of its choice (probably the closest object), resulted in a pretty successful sequence of in-focus or acceptably sharp images.

Battery Life

The GH4 uses the same DMW-BLF19 battery as its predecessor, which will be good news for anyone already using a GH3. Its 14Wh capacity helps the camera achieve a pretty respectable 500 shots per charge, when tested to the CIPA standard. These numbers don't necessarily represent the number of shots you'll actually get when shooting with the camera but give a good idea of how it'll compare to other models. 500 shots per charge is a good figure, especially for a mirrorless camera, which is depends on an electronic screen for its use.