Sony’s alpha 7S Mark III is the third iteration in the most video-focused of the company’s a7 series of full frame cameras. It’s essentially a native 4K camera with impressive video specs and a revised user interface. It can capture UHD 4K footage at up to 120p in 10-bit 4:2:2 encoding and promises 16-bit Raw video output.
- 12MP BSI CMOS sensor
- Bionz XR processor
- On-sensor phase detection
- ISO 80-102,400 (expandable to 40-409,600)
- 9.44M-dot EVF with 0.91x magnification
- 4K video at up to 120p, 60p for ‘at least an hour’
- 16-bit Raw video output at up to 60p
- 10-bit 4:2:2 internal capture (in codecs including H.265 and All-I H.264)
- Fully articulating LCD
- 5-axis in-body stabilization with SteadyShot active mode
- Twin card slots that each accept either SD or CFexpress Type A
Key features
For the Sony A7S III, it’s really all about the 4K video from the 12.1-MP sensor. And specifying a sensor which such a low resolution – by modern standards – might just well be Sony’s moment of genius, instead of fitting a much higher-resolution sensor just to steal a few headlines or make stills shooters happy.
Instead of using valuable computing power – and the heat it generates – with pixel binning or line skipping high-resolution files to get them down to 4K size, the Sony A7S III is designed around full-frame 4K shooting. The larger-but-fewer pixels on the sensor not only gives huge benefits at high ISO but is also read much faster, which hugely reduces the dreaded rolling shutter that blights many mirrorless cameras.
The powerful new processor means that a huge range of 10-bit 4:2:2 codecs can be used at native speeds up to 120p in 4K. And you can go to 240fps in HD, still in 10-bit. All while retaining the use of the advanced AF in all its glory. No longer is there a limit to the AF working when the more data-hungry settings are used. Everything works at all settings.
Well, maybe there are a couple of tiny limitations, but we can forgive them from a small camera that can shoot at 4K/60p full frame internally with no crop, in 10-bit 4:2:2 with no limits on recording time and little potential to overheat.
The only thing to note is that there is a small 1.1x crop when shooting 4K/ 120p. And if you use the most advanced in-body image stabilisation system, every setting gets a 1.1x crop. And the only way to get 240fps is to use the camera in HD S&Q mode which means it doesn’t record audio.
With an ISO range that goes from 80-102,400, expandable as low as 40 and high as 409,600, then it’s a camera that can pretty much see in the dark. And this sensitivity means there is a huge amount of dynamic range, which can be expanded according to the settings you choose. With Sony S-Log2 and S-Log3 as well as HLG settings, you can maximise the highlight and shadow detail at will.
And if you demand the ultimate quality, the camera will output 16-bit raw over HDMI, which can be saved as 12-bit Log ProRes Raw by a recorder like an Atomos Ninja V.
Any filmmaker knows audio is just as important as the images, which is where mirrorless cameras can be a let down – forcing users to go for external audio recorders. The A7S III audio is good, with four channels in linear PCM ideal for Sony’s XLR adapter. And the controls are good.
For stills, it might only be a 12.1MP sensor but it is a full-frame camera, so that offers significant low-light benefits. And it can shoot compressed or uncompressed raw files at 10fps for up to 1000 shots. Until very recently, those sort of specs would have made it one of the top choices for sports photographers, especially as it’s allied to Sony’s fast and precise AF system. Don’t write the camera off as a stills machine. It may not offer the resolution for huge prints or croppability of cameras with four times its resolution, but many magazine covers and spreads have been printed from 12MP cameras. It’s far more capable than just taking behind-the-scenes snaps or web-resolution pics.
Build and handling
Sony’s cameras continue to evolve and the A7S III takes the learnings from the A7R IV and improves on them. There are better buttons, a deeper grip, a separate mic jack, fully articulating screen, and a full-size HDMI port which comes with a screw-on cable cage. The REC button has been made bigger and moved to the top plate. And the Movie and S&Q buttons are next to the usual PASM settings on the dial, instead of the other side of the custom buttons. It just makes things easier to change.
And when using manual focus in video, as many do, pushing the AF button now gives you one-shot auto focus.
The camera is slightly bigger than other A7 cameras with the new bump on the top plate housing one of the best electronic viewfinders we’ve ever seen. The camera is weather sealed and solid, and uses the same battery as other later Sony cameras. This lasts well, but does get eaten up if you are using 4K 120p settings with IBIS at high bit-rates. That’s something its lesser siblings simply can’t do.
In terms of storage, Sony has really scored as there are two UHS-II card slots that also take the new CFexpress Type A cards. If you use fast SD cards, these are good enough for most codecs. But use the most intensive settings, such as 4K/120p, S&Q, All-Intra, and you need CFexpress Type A cards.
And as the card slots are matched, you can do hot card swapping, unlike some cameras which have two different cards. And the camera’s USB-C socket can now accept power delivery, for example from a power bank. So by hot swapping cards, you can carry on shooting for a very long time.
Sony’s rear screen is a flip screen, and is a touchscreen where you can navigate through the much improved menu system. Or you can use the dials, if you prefer.
One small improvement is that video clips now can be named, rather than them always defaulting to a standard format.
Below is a gallery of still images taken at a series of different ISO settings. They are not displayed here at full resolution as this is a pre-production camera, but you can still get an idea of how well the Sony A7S III performs even at ISO 102,400.
Performance
Although we were only using a pre-production prototype so it’s not exactly as will be delivered to buyers, it was easy to see that the quality of the files in 4K and HD is stunning. The colours are bright yet natural, there is lots of dynamic range and the high-ISO performance is off the scale. Sony claims up to 15-stops of dynamic range, and we saw nothing to disprove that.
It wasn’t just the high bitrate 4K codec files that were impressive. The results using the Sony H.265 format were equally impressive, and the HD was stunning too. The standard colours are some of the best we’ve seen from Sony, and Log shooting helped get even more dynamic range for more hardcore grading. The files are full of colour info, so this is finally a Sony mirrorless camera that works perfectly in Log.
Although Sony doesn’t say so, we believe there is a dual ISO circuit function which bases at ISO 640 and again at 16,000. Files shot at ISO 16,000 were cleaner than at 12,800 for example. We found that up to ISO 6400 we were more than happy with the results. When it gets darker than that, switch up to 16,000. Of course, the camera does go up to ludicrous high figures which would get you out of a hole. Such as being inside a dark hole with no light.
The AF system is also second to none, thanks to its customisation for video use. It can be used to rack focus smoothly and organically, depending on the AF focus settings. So fast AF is good for stills, but for video use you usually want something more controlled. The speed of focus can be adjusted over seven increments from fast to slow, and the transition speed in five steps. And it works in very low and bright light.
With great focus tracking, helped by touch-to-focus on the screen which then tracks the object as it moves, it’s Sony’s best yet.
Also good is Sony’s IBIS which has two modes, standard and active. Active is best for video but crops in 10% apart from 4K/120p, where it’s already cropped. It’s good, though it’s not the best on the market.
And in fact pretty much our only gripes were around the tools for filmmakers. There is no option to change shutter speed to shutter angle, and there are no waveforms to monitor the footage. But those are pretty small issues on an otherwise incredible camera for making movies.
