As video cameras go, the Panasonic Lumix DMC-GH4 and Sony Alpha 7S are very DSLR-like in shape. A four-fold difference in sensor size, and a significant gulf in price suggests this may be the only similarity. However, in terms of intent, they're not as different as all this might lead you to expect. We've already had a quick look at the new features of the GH4 but here we're going to test the two cameras side-by-side - not necessarily to find a single 'winner' but to see where each camera's strengths and weaknesses lie.
Not just stills, not just movies
Both manufacturers make clear that these cameras are both intended for videographers just as much as they are for stills shooters. Both are built around a conventional stills form-factor but with video capabilities and supporting functions pushed toward the forefront. As such, we'd expect the two to be judged on a similar basis. We'd expect better performance from the Sony's much larger sensor to help to justify its price tag, but the requirements of the users are likely to be similar.
DSLRs capable of shooting HD video have existed for a little under six years and, though video initially seemed to be a feature added simply because the manufacturers could, it's become seized upon by a growing band of users. At the pro end of the spectrum, cameras such as the Canon EOS 5D Mark II have changed expectations of what size a camera could be, but putting video capability in the hands of photographers has also inspired some of them to think beyond single frames.
For the most part, however, the majority of modern mirrorless cameras and DSLRs still don't offer users much support for their video function. Video capability is there but, even in the circumstances where a decent level of manual control is given, tools such as focus peaking and zebra that have been standard on video cameras for years are missing. And this extends even to cameras such as the Canon 5D Mark II and Nikon D800, whose respective manufacturers were happy to promote the video features of, despite the fact they were both somewhat lacking. Canon has subsequently upped its game with the EOS 5D Mark III and the lessons it's learning from the development of its Cinema EOS line, but generally video is promoted much better than its supported.
Beyond the [REC] button
The Panasonic GH4 and Sony's a7S step round these pitfalls, both offering focus peaking and zebra highlight warnings to help videographers get footage that lives up to the cameras' capture capabilities (both are features that can be provided by external monitors so can be added to other cameras if you're willing to rig them up). They also have the add-on accessories available to allow use of industry-standard audio or video connections.
Another shortcoming of many 'HDSLR's is that they capture the relatively low resolutions of video by only sampling some horizontal lines of their sensor - a process that's become known as line-skipping. This leads to lower vertical resolution in the video, along with a greater risk of moiré. The GH4 and a7S avoid this, and both are able to read out at least 4K regions of their sensors at 30 frames per second.
However, just because they go to unusual lengths to accommodate the videographer, this doesn't mean any compromises have been made to the feature sets they offer the stills shooter. Noticeably, the Sony offers the same handling and controls as its more stills orientated a7 and a7R models, while the GH4 adds improved autofocus to the GH3's well thought-out and DSLR-like stills handling.
The table below sets out how the cameras compare:
|Panasonic Lumix DMC-GH4||Sony Alpha 7S|
|Sensor format||Four Thirds
|Sensor size (mm2)||225
|Lens mount||Micro Four Thirds
|Max video Res (Internal)||Cinema 4K (4096 x 2160)
||Full HD (1920 x 1080)|
|Max video Res (with external recorder)||Cinema 4K (4096 x 2160), 10-bit
||4K (3840 x 2160), 8-bit|
|Electronic viewfinder resolution||2.36m dots (1024 x 768px)
||2.36m dots (1024 x 768px)|
|Rear LCD resolution||1.04m dots (720 x 480px)
||0.92m dots (640 x 480px)|
|Control dials||Two plus rear dial
||Two plus Exposure comp|
|Customizable buttons||Five, plus five on-screen 'buttons'
||Nine (including dual-function AF/MF / AEL button)|
|Battery life (CIPA)||500 shots||380 shots|
|Dimensions||133 x 93 x 84mm
||127 x 94 x 48mm|
|Price (MSRP)||$1,699 / £1,299 / €1,499||$2,499 / £2,099 / €2,399|