Overall Performance and operation
In terms of handling, the GH2 is a near match for the camera it replaces, as well as for the G2 and G10. With the exception of the more compact GF1 and GF2, all of Panasonic's G-series have handled in essentially the same way since the system's inception. Design-wise the GH2 is styled to resemble a small DSLR, and this is reflected in the handling.
Like the GH1 before it, the GH2 is a reasonably fast and responsive camera in both still and video shooting modes, although we're a little disappointed that Panasonic didn't take an opportunity to properly overhaul its menu system. Although much prettier than the rather monochromatic menu systems of its predecessors, the GH2's menus remain lengthy and often rather confusing. Fortunately, the camera features a useful 'Quick Menu' to access the most commonly-changed functions, and key shooting settings can also be assigned to the GH2's three Fn buttons.
With the exception of video shooting, using the GH2 feels just like using a more traditional system camera. What sets it apart from most of its competitors is the high resolution EVF, which makes video shooting immeasurably more pleasant. With the Sony Alpha SLT A33 and A55, the GH2 is our favourite DSLR-style camera to shoot movies with. Not only does using the EVF give you a better idea of exposure and focus during video shooting, it also allows a more stable shooting platform when filming without a tripod.
Operation and handling
The GH2's shooting experience has subtly changed from the GH1. The control dial has moved from the front to the rear of the body for control by your thumb, and the movie record button is now on the top plate. Overall we prefer this layout, as we found the GH1's forefinger-controlled dial to be relatively poorly positioned, making it all-too-easy to change settings accidentally. The GH2 now has even more direct external control via the AF area selection dial, plus more customizability via the three Fn buttons. This makes it one of the very best cameras in its class in terms of usability while shooting, even without considering the additional options offered by the touchscreen.
We've mentioned it before, but something we really like about the GH2's touchscreen is that Panasonic doesn't force you to use it, so a GH1 user coming to the GH2 doesn't need to worry about learning a whole new way of working unless they want to. Initially, we didn't find ourselves using the GH2's touch screen all that much, but after spending more time with the camera we have found that activating and accessing certain functions by touch makes a lot of sense, and we adapted our way of working accordingly.
A good example is touch-based focus point selection. The ability to quickly and intuitively designate your desired focus point simply by touching the screen is remarkably useful, and makes it easy to achieve precise focus exactly where you want. We're not so enamoured of the touch shutter, though, which goes one step further and takes a picture whenever you press the screen - not only is it a recipe for camera shake, it's also the best way we've yet found of filling your card with inadvertently-taken shots.
Specific handling issues
We haven't been very enthusiastic about touch-sensitive screens on cameras in the past, mainly because all too often, they haven't been implemented very well. However, in the G2, and now the GH2, Panasonic has done a really good job, we think, of melding this new technology with a more familiar, 'traditional' DSLR-like interface. The more compact GF2 is a slightly different proposition - its streamlined ergonomics encourage you to actively engage with the touchscreen - whereas the G2 and GH2 retain plenty of external controls.
Although the GH2's screen isn't quite as clever as the multi-touch capable capacitive screens used some smartphones and tablet computers, it has the advantage that it can still be operated with wet hands, and with gloves on (as long as they're not too thick). If you own a device with a capacitive screen, applying pressure to tap and swipe feels odd at first, but you soon get the hang of it.
After spending an extended amount of time with the GH2, the only touch function that we'd definitely be inclined to turn off is touch shutter. As we've already mentioned, pressing the back of the camera to trigger the shutter is often enough to cause shaken pictures, particularly when working with longer exposures, but quite apart from this, we found that this way of working just feels strange. In contrast, using the screen to specify the focus point and then taking a picture in the conventional way using the shutter button works better, and feels more natural.
Setting the GH2's main display aside for a moment, we've already mentioned the EVF several times in this review, and whilst we love its large, bright image and its high resolution, we're less keen on the automatic EVF/LCD switch sensor built into its eyepiece. This sensor is designed to turn the main display off when it senses the photographer's eye being placed to the EVF, but unfortunately it is extremely sensitive (even when set to its 'low' sensitivity setting in the Custom menu). We have found that if anything gets within roughly 1.5 inches of the switch's sensor in a straight line it is enough to turn the rear LCD off, which is intensely irritating when you're trying to manipulate the screen by touch. Fortunately, the automatic switch can be disabled, and there is a manual EVF/LCD toggle to the left of the GH2's viewfinder.
As we've come to expect from Panasonic's G-series, the GH2 is a responsive camera in almost all areas of its operation. Startup and shutdown are prompt, getting in and out of menus is all but instant, and whether you prefer manual buttons points or on-screen touch-activated controls, the GH2 won't keep you waiting. In fact some operations are quicker using the GH2's touch interface; whether it's via the Q.Menu or the options that appear when you press the direct-access buttons, it's often faster to stab at an icon on the screen than scroll to it using buttons or dials.
The GH2 isn't the fastest camera in its market sector though - its continuous shooting performance isn't great, in terms of either maximum frame rate or buffer, and like the GF2 it takes a (slightly disorienting) moment to acknowledge that you've asked it to stop shooting movies. Battery life is relatively poor too, and we struggled to get a full day's worth of shooting out of a single battery charge. This isn't helped by the GH2's battery indicator, which has a nasty habit of going from displaying a healthy charge to almost empty with very little warning. In general, though, the GH2 is a pleasantly fast camera which satisfies most of the expectations implied by its price point.
Continuous Shooting and Buffering
The GH2 has four continuous shooting modes, Super High, High, Medium and Low. Super High offers an impressive-sounding 40fps for bursts of up to 1 second, but resolution is limited to 4MP. High offers (on paper at least) the fastest full-resolution continuous shooting speed of any Micro Four Thirds model to date at 5fps, but the camera can't maintain a live view feed between shots; this is only available when using the medium and low continuous shooting modes.
We used Panasonic's 14-140mm HD lens to perform the continuous shooting tests, and we found that in Continuous High ('H') mode, when shooting JPEG files the GH2's shooting rate varies depending on the focal length. It's not entirely clear why, but it is possible that the differences we've observed are caused by the varying amounts of in-camera distortion correction required at the lens' different focal lengths. Whatever the cause, it is essentially impossible to specify a single maximum shooting rate for the GH2 while using 'native' Micro Four Thirds lenses. It is interesting to note that we had the same experience with the recently reviewed Lumix DMC-GF2.
Shooting high quality JPEGs, in our tests we achieved between 4 and 5 frames per second maximum continuous shooting rate in 'High' burst mode, depending on focal length. Using the 14-140 zoom, we managed 5fps at 14mm for 7 frames, after which the frame rate dropped to around 2.5fps. At 50mm, we attained 4fps for 7 frames, before speed dropped to 0.5 frames, and at 140mm, we could shoot at 5fps for 6 frames, before the frame rate dropped significantly, to approximately to around 0.4fps. (For these tests we used a Sandisk Extreme Pro 8GB 45MB/s UHS-1 SDHC card.)
In RAW mode, regardless of focal length, the GH2's continuous shooting rate peaks at between 3.5 and 4fps, for a maximum sustained burst of 7 frames. After this burst, a lower frame rate is maintained of roughly 0.3fps. It takes 13 seconds for the buffer to clear after a burst of images but it is possible to shoot single frames whilst the buffer is clearing.
Using the Olympus 50mm f/2 Macro lens with Panasonic's DMW-MA1 adapter ensures that no lens corrections are being applied, and this setup gives us 7-8 high quality JPEG frames at a maximum framerate of approximately 5fps before the framerate dropped. When 'medium' continuous shooting speed is selected, the GH2 can deliver 3.5fps for 5-7 frames in a burst before it has to slow down. Arguably, this mode is more useful than 'H' since live view is maintained between frames, and as such it is worth noting that set to 'M' continuous advance, the GH2 gives better performance than the G2 set to 'H'.
Autofocus speed / accuracy
Panasonic's G-series has set the standard for contrast-detection autofocus for some time now, and the GH2 raises the bar again. At 120Hz the GH2's sensor's readout speed is considerably better than its siblings, which pays off in noticeably improved contrast-detection AF compared to the GF2 and G2. In fact, for day to day (i.e. non-specialized) use we consider the GH2's CDAF system to be virtually on a par with most competitive phase-detection systems in terms of its speed.
As well as being pleasantly fast and responsive, focus accuracy is impressive too. As we've come to expect from cameras with high-end CDAF systems, the GH2 is unerringly accurate with static subjects, and you can be confident that when it confirms the subject is in focus, it really means it. It is easy to overlook Face Detection, but for casual photography it is enormously useful. We're not completely sold on the need for Face Recognition, but it works very well.
The GH2's AF tracking mode is also pretty effective, reliably following subjects as they move around the screen. Although it is undoubtedly slightly quicker than the G2 and GF2, the GH2's autofocus system has similar difficulties when it comes to following subject movement towards or away from the camera. Basically, the AF system isn't always able to keep up with the camera's understanding of where the subject has gone, meaning that there's sometimes a little shutter lag while it catches up. If you continue to track the subject the camera will tend to get the focus right, but this does mean you sometimes miss the perfect moment when working with fast-moving subjects. (You can of course turn Focus Priority off, but this risks the image being out-of-focus). Hunting - where the AF system is unable to stay with its target and makes large experimental adjustments to re-acquire it - can also be an issue with the GH2, but only occasionally.
To a large extent, this is simply a limitation of CDAF technology. A CDAF system has no way of knowing whether a subject is sharp or not without shifting focus back and forth to check the difference in contrast. When it comes to continuous CDAF, matters become even more complicated, since if the subject moves out of the plane of focus the system has no way of telling whether it has moved to a position behind the focal plane or in front of it, again, without shifting the focusing element/s back and forth to check. Not only is this more time-consuming than the equivalent operation in a phase-detection system, it also makes 'predictive' AF more processor-intensive. Obviously this creates problems when it comes to accurately tracking subjects moving towards or away from the camera.
The increased speed of the GH2's sensor readout compared to other G-series (and indeed the Olympus PEN) cameras means that it can output subject contrast information more quickly, and we're left in no doubt after using the camera for some time that the GH2 offers the best all-round CDAF performance of any current camera. Ultimately though, while it bests its Micro Four Thirds peers, the GH2's continuous AF performance isn't quite up there with the phase-detection systems of competitive DSLRs.
Where continuous AF comes in really handy is when shooting video. Although it displays the characteristic (and to some extent inevitable) CDAF 'wobble' when it initially locks onto a subject, focus is very smooth, and generally very accurate. Just as with still shooting, continuous AF can lag a little behind subjects which are either moving very quickly or are closing rapidly with the camera, but this is far less noticeable in movie footage.