Compared: Panasonic GH4 and Sony a7s

In terms of video features, the Sony Alpha 7S has one of the more comprehensive offerings on the market. However, it can't keep pace with the Panasonic GH4, which benefits from several more generations of development, and the feedback from professional video shooters.

Here's a compartive list of the features offered by the two cameras for videographers.

  Panasonic GH4 Sony Alpha 7S
Max video Res (Internal) Cinema 4K (4096 x 2160)
Full HD (1920 x 1080)
Highest bitrate 1080 video • 200Mbps 24p
• 200Mbps 60p
• 50Mbps 24p
• 50Mbps 60p
Movie-targeted color modes • Cinelike D and Cinelike L
(Hue)
• Picture Profiles, SLog2
(Black Gamma, Knee, Color Phase)
Black level control • Master Pedestal (-15 to +15) •Black Level (-15 to +15)
Luminance range options • 0-255, 16-255, 16-235 • No
Audio level control • -12 to +6dB • 0-31
Mic level display • Optional • Optional
Sound output • Realtime/Rec Sound • Live/Lip Sync
Peaking • 2 Levels
• 3 Colors
• 3 Levels
• 3 Colors
Zebra • Two presets
• 105% – 50%
• 100+ – 70
Markers • Center
• Guide Lines
• Center
• Aspect
• Safety Zone
• Guideframe
Synchro Scan • Yes • No
HDMI Output • FHD 4:2:2 8-bit/10-bit*
• 4K 4:2:2 8-bit/10-bit*
• FHD 4:2:2 8-bit
• 4K 4:2:2 8-bit
Clean HDMI Output • Optional • Optional
Time Code • Free Run / REC Run
• Includes dropped-frame option for NTSC (59.94fps) modes
• TC / UC
• Free Run / REC Run
• Includes dropped-frame option for NTSC (59.94fps) modes
Time/Gain display methods • SEC/ISO
• ANGLE/ISO
• SEC/dB
• SEC/ISO
Color Bars • SMPTE
• EBU
• ARIB
• No
Variable Frame Rate • 2fps (1200%) high-speed - 96fps (25%) slow motion • No (Though 720p footage can be shot at 120p and 100p then used as slow-motion footage with suitable editing software)

*Internal recording not available with 10-bit HDMI mode.

There's a fair amount there that no other mainstream stills/video camera offer. In addition, both companies sell accessory units that offer industry-standard connections for audio and, in Panasonic's case, video.

The Sony XLR-K1M adapter adds two XLR mic inputs with individual control over input levels. This unit connects to the camera's Multi-Interface connector in its hotshoe and allows the connection of line-level or mic-level (with or without provision of 48V phantom power).

The Panasonic DMW-YAGH module is rather more extensive addition, adding not just XLR inputs (with the same line, mic, phantom power mic options), but also features four SDI connectors (2 x HD and 2 x 3G), allowing 4K, 1080p60 and 1080p30 output, in various combinations. The YAGH also includes a timecode input socket and full-sized HDMI out, rather than the camera's mini HDMI connector. The unit is powered by a 4-pin XLR 12VDC connector.

Video sampling / quality

Here we can see how the GH4 and a7S compare, in terms of the resolution of the footage they can shoot. Both were recorded internally at the camera's highest quality settings.

As you can see from the symmetrical seimens stars, both cameras are creating their video from the same number of horizontal and vertical lines (the line skipping method some other cameras use results in a lower vertical sampling frequency than the horizontal sampling frequency - meaning you get lower vertical resolution than you'd expect).

However, while both cameras show similar amounts of detail, the Sony's output has virtually none of the interference patterns that the GH4 shows. The difference between the two is aliasing - frequencies higher than the camera can sample appearing, falsely, as low-frequency patterns.

Panasonic, in its 1080 mode, is pixel-binning - combining data from multiple pixels before reading them out. The Sony, by comparison is oversampling the scene (reading out a 4K region of the sensor) then processing that data before downsizing. Indeed you can get a similar result from the Panasonic by applying a slight guassian blur to the 4K image before downsizing to 1080.

This highlights several things. Firstly that the Sony can output a 4K signal from the same crop as it used for 1080, whereas the Panasonic uses a smaller crop for its 4K footage. This suggests the Panasonic could probably produce similar video quality to the Sony if it could output 1080 footage made from the 4K readout region of the sensor.

Initial impressions:

We already have a good feel for how the two cameras work in stills - the behaviors of both are closely related to existing models. On that basis, the GH4 is the slightly nicer camera to shoot with, mainly because it works slightly more like a conventional mid-level DSLR but also because it's a little bit more comfortable to hold. The GH4 also has access to many more native lenses than the Sony, which provides greater flexibility. We'll be looking more closely at the image quality of the two later in the review.

In terms of video features, the GH4 looks slightly better equipped, whether in terms of a handful of pro-orientated features or the provision of more, and higher quality, output options. However, these things can't be judged solely on number of features - the provision of Sony's 'Picture Profile' system, which allows very flat SLog2 gamma, makes the a7S look more attractive as a camera if your workflow is expected to include significant post-processing. The addition of a (currently expensive) external recorder also allows the a7S to close the gap on the Panasonic when it comes to output resolution and compression, too. Again, this is something we'll look more closely at as the review continues.

Beginner videographers are likely to find the a7S's Auto ISO in manual exposure extremely useful, as it takes some time to get used to manually adjusting ISO on-the-fly, even with the GH4's handly touchscreen controls. The A7S's ability to zoom-in for focus fine-tuning during video shooting was another major boon. We'll look into what a more experienced user can do with the cameras, in the coming weeks.