 Preview based on a production GH2 with firmware V 1.0 When Panasonic first launched the GH1, its second Micro Four Thirds camera, it was widely seen as simply being a G1 with video shooting and a considerably more expensive kit lens. And, if your primary concern was stills photography then this wasn't an entirely unreasonable assessment. However, its real appeal was not that it had video, but that it offered what was, at the time, some of the most flexible, high quality video available. Again, the 14-140mm F4.0-5.8 kit zoom may not have been cheap but it had been specifically designed and built with fast, quiet autofocus and stepless aperture control to allow AF during movie shooting and exposure changes without sudden changes in brightness. Now that the G2 (along with the majority of contemporary cameras) is able to capture HD video, the distinctions between just being able to shoot HD and to really control it become more apparent. Stills shooters may get some advantage from the new, higher resolution sensor but the main differences between the GH2 and G2 are the ability to control the movie shooting process (both in terms of frame rate and shutter speed). In the years since Olympus and Panasonic jointly announced the Micro Four Thirds standard there have been eight models launched to date, seven of which share the same 12MP sensor. The only exception was the GH1 which, despite its 12MP output actually featured a 14MP sensor. The sensor was slightly larger than the format's imaging circle, which allowed it to deliver images in different aspect ratios while retaining the same image diagonal. And now the GH2 follows the same pattern, shooting 16MP images using its brand-new, similarly over-sized 18MP sensor. This sensor is capable of much greater readout speed (120Hz) than its predecessor, bringing a host of benefits. Videographers will see an improvement in the quality of the highest quality output - the 1080i output is derived from 60p or 50p capture, rather than doubled-up from 24p or 25p on the GH1. The faster readout also means the AF system can more frequently check the accuracy of its focus, which promises faster autofocus (on lenses that can respond quickly enough). Finally, the faster readout means the live view is updated 60 times a second (rather than 24fps displayed at 60hz), giving a smoother viewing experience with less tearing. The electronic viewfinder has also been slightly widened - it now shows 852 x 600 pixels as opposed to 800 across - which allows it to display 16:9 and 3:2 previews without the need for such extensive cropping as before.
Compared to GH1 - key differencesThe GH2 might look very similar to its predecessor at a casual glance but there are some major differences between the two models. Let's have a look at the main changes:
Key feature comparison (vs G2 vs GH1)Like the GH1, the GH2 is distinguished from its G-series contemporaries by its video shooting capabilities. The GH2 is a far more serious video shooting tool than the G2, and indeed the majority of its competitors - both mirrorless and DSLR. The GH2 offers a similar video specification to the GH1 but with one important difference - the sensor no longer doubles-up its sensor output in order to create its highest-speed video (the GH1 sensor could capture at 24 or 25 fps, which was then put out as 60i or 50i footage). Instead, the latest sensor can capture progressive (whole frames) at 60 or 50 fps. Its output is still limited to 60i or 50i because there are no common ways to distribute 60p or 50p footage, but this should certainly improve the output quality. In its 'Variable Movie Mode' the GH2 also has the ability to save footage at a different frame rate from the one captured - allowing slow-motion or high-speed effects. From a still photography point of view the GH2 brings very little that is 'new' to the G-series apart from its increased resolution - up to 16MP from 12.1MP. This makes the GH2 the highest resolution camera in Panasonic's Micro Four Thirds range, and a maximum ISO of 12,800 makes it (at least on paper) the most versatile too. Like the G2, the GH2's LCD screen is touch-sensitive, but also like the G2, it is not 'mandatory'. In other words, GH1 users upgrading to the GH2 with no interest in experimenting with the touch technology can more or less ignore it if they wish. (Unfortunately, though, it doesn't share the GF2's new 'designed for touch' interface.)
Compared to: G2 and GH1
Multi-Aspect SensorLike the Panasonic LX5 and the GH1 before it, the GH2 uses a multi-aspect ratio sensor. It's slightly larger than usual for Four Thirds, and at any given aspect ratio (even at 4:3) the camera only uses a crop from the total available sensor area.
At first sight this may seem strange but the result is that the lens offers the same diagonal angle of view regardless of selected aspect ratio, making it much easier to get a feel for the behavior of the lens. It also means you make the most of the sensor area, getting similar pixel counts in all modes.  If you're new to digital photography you may wish to read the Digital Photography Glossary before diving into this article (it may help you understand some of the terms used).
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