Sony A7s vs A7R vs A7 comparison: 02 Video
Aside from ISO performance, the other key difference between the Sony A7s and its Alpha stablemates comes in the shape of the A7s’s advanced video capabilities.
The Sony A7 and A7R both offer Full HD video (AVHCD progressive, 1920x1080p @60p), but the A7s also brings 8-bit 4:2:2 4K video capture, stealing a march on other DSLR and Compact System Camera manufacturers, aside from Panasonic – a company which, like Sony, has an enviable heritage in the professional camcorder business.
Aimed squarely at commercial videographers, the A7s is capable of ‘Clean HDMI’ output at 4K (3840×2160) resolution, meaning that uncompressed footage can be recorded to a 4K-compatible recorder attached to the camera, or displayed on a compatible monitor or TV.
In fact, 4K has to be recorded to an external device – only HD footage can be saved internally.
A superimposed time code when Clean HDMI is selected, with Record Run (for advancing the time code only while recording) and Free Run (which advances the timecode at all times), and both drop frame and non-drop frame options available.
The A7s offers a wider range of recording frame rates, including 4K at 30p/24p and Full HD at 50p/25p, as well as a slow-motion standard HD resolution (1280×720) option – although you’ll need to switch from full-frame to the cropped APS-C mode to enable it.
In slow-motion mode, the A7s burns through footage at 120fps. Played back at 24p, this gives a speed that’s 5x slower than normal.
What’s more, Sony claims that the sensor in the A7s is the first full-frame one in the world to be capable of full-pixel read-out without pixel binning when shooting video.
‘Binning’ is a process whereby groups of pixels essentially act as a single pixel, reducing the effects of noise with the trade-off being a reduction in resolution.
The A7s doesn’t let any information go to waste – data is taken from every pixel – although this only counts when movies are being recorded at 24p/30p(25p).
In addition to recording footage in the Sony-and-Panasonic-developed AVHCD Progressive format, the Sony A7s introduces the XAVC S format to the Alpha camera range.
This enables higher-quality Full HD recording at an increased bitrate of 50mbs, although Sony recommends using an SDXC memory card of Class 10 or higher when shooting movies in this format.
A new Dual Record function debuts on the Sony A7s too, enabling the camera to capture a 720p stream alongside the higher 50mbs XAVC S footage.
To improve dynamic range and make it easier to bring out detail, the A7s uses Sony’s proprietary S-Log2 gamma setting.
The S-Log2 curve is designed to produce a dynamic range that’s 1,300% wider than standard gamma, reducing the chances of burned-out whites and clipped blacks.
Footage might look flat straight out of the camera, but this improves the colour grading possibilities during post-production.
You can also apply your own distinctive look to movie footage before you shoot, by adjusting gradation, colour tone and intensity and other effects, and then saving this mix as a Picture Profile (the A7s has seven such profile slots available).
Needless to say, the video functions of the Sony A7 and A7R don’t come close to those in the A7s.
PAGE 1 – Sony A7s vs A7R vs A7 comparison: 01 Sensor resolution and ISO
PAGE 2 – Sony A7s vs A7R vs A7 comparison: 02 Video
PAGE 3 – Sony A7s vs A7R vs A7 comparison: 03 Design and build quality
PAGE 4 – Sony A7s vs A7R vs A7 comparison: 04 Continuous shooting and battery life
PAGE 5 – Sony A7s vs A7R vs A7 comparison: 05 Autofocus and metering
PAGE 6 – Sony A7s vs A7R vs A7 comparison: 06 Price
PAGE 7 – Sony A7s vs A7R vs A7 comparison: our conclusion
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