Sony a7S III review

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Sony a7S III

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

The Sony a7S III sell for around $3500. This is a $500 premium over 2015’s Mark II but still $500 lower than the launch price of the Panasonic Lumix DC-S1H, which we see as its closest competitor.

I. What’s new and how it compares

What's new and how it compares Sony a7S III

Key takeaways:

  • BSI CMOS sensor with phase-detection elements
  • Updated processor improves responsiveness and enables high bitrate video
  • UHD 4K from full-width at up to 60p, native UHD from 1.1x crop at up to 120p
  • H.265-based XAVC HS and All-I H.264 XAVC S-I options
  • 60p recording for ‘at least an hour’ at room temperature

Sony says the a7S III was developed with reliability as a foremost concern. So, rather than trying to shoot 8K or even oversampled 4K, it shoots essentially ‘native’ 4K. This is likely to result in slightly less detailed footage than some of the company’s existing, less video-focused models, but with the benefit of improved rolling shutter and extended record times.

As with the previous a7S models, Sony talks about the camera being a good stills option for low light, but the bulk of the advances in the camera are on the video side of the ledger.

Sensor and processor

While the 12MP resolution hasn’t changed, the a7S III has a different sensor to the one used in its two predecessors. It moves to a BSI design, which Sony says will boost its low light performance (though in the examples we’ve previously seen, it’s a change that makes less and less difference, the larger the pixels are). Interestingly, it features a base ISO of 80, which could bring greater dynamic range.

What’s definitely improved is the sensor readout rate. The a7S III can shoot UHD 4K at up to 60p from its full width (4.2K) or at 120p from a native UHD 4K region (a 1.1x crop).

As well as an updated sensor, the a7S III is the first Alpha camera to feature the new Bionz XR processor. It’s a two-chip processing system that Sony says allows image and video processing to be handled entirely separately from file management and handling, which should reduce latency and allow more complex image processing above and beyond what the claimed 8X increase in processing power brings.

Updated autofocus

Unlike previous ‘S’ models, the a7S III includes on-sensor phase detection elements, allowing more decisive, depth-aware focusing. The camera includes the latest version of Sony’s autofocus system, which can automatically detect faces, eyes and heads, and use the appropriate focus method. This lets you use face detection AF, including in video recording, without the risk of the camera refocusing to a different person if your original subject turns away.

Sony says the new processing improves the performance of the recognition aspect of the AF system.

Not all of the video AF system is quite as sophisticated as in stills: you have to tap to initiate tracking, rather than being able to pre-position an AF point, and there’s no animal eye AF in video mode. But it should be a huge leap forward compared to the contrast-detection of the previous a7S cameras. As you’d expect, video mode lets you specify the speed of AF and how long it waits before switching subjects.

White balance sensor

White balance sensor Sony a7S III

It’s been a long time since we’ve seen a dedicated external white balance sensor on a camera (Range-topping DSLRs from Canon, Nikon and Olympus used to have them), but they’ve become common on smartphones. And now there’s one on the front of the a7S III.

Combined with the option to control how quickly white balance reacts to changes in the scene (Exposure/Color|White Balance|Shockless WB), it’s aimed at reducing unpredictable white balance shifts as you’re capturing video (if one color suddenly fills the frame, for instance).

Video compression options

Perhaps the most significant improvement for most videographers is the more extensive range of compression options. The a7S III goes far beyond the 8-bit capture of previous a7 cameras. Not only does the camera gain a 10-bit 4:2:2 version of the (H.264-based) XAVC S encoding, it also gains an H.265-based variant called XAVC HS. There’s also an H.264 All-I option called XAVC S-I.

UHD 4K options

Most of the camera’s UHD footage (at least up to 60p) is taken from essentially the full 4240 pixel width of the sensor. This is sufficient that Sony could provide DCI 4K (4096 x 2160) options, but such options are not present.

Frame rates Bit-depth/ chroma Chroma sub-sampling Bitrate
(Mbps)
XAVC HS
(H.265)
  • 120p
10-bit 4:2:2
  • 280
4:2:0
  • 200
  • 60p
4:2:2
  • 200
  • 100
4:2:0
  • 150
  • 75
  • 45
  • 24p
4:2:2
  • 100
  • 50
4:2:0
  • 100
  • 50
  • 30
XAVC S
(H.264)
  • 120p
10-bit 4:2:2
  • 280
8-bit 4:2:0
  • 200
  • 60p
10-bit 4:2:2
  • 200
8-bit 4:2:0
  • 150
  • 30p
  • 24p
10-bit 4:2:2
  • 140
8-bit 4:2:0
  • 100
  • 60
XAVC S-I
(All-I H.264)
  • 60p
10-bit 4:2:2
  • 600
  • 30p
  • 300
  • 24p
  • 240

Boxes marked in green require at least a V60-rated SD card. Boxes marked in red require a V90. Bit-rates around 100Mbps require a V30 card. CFexpress cards can record all modes.

One thing that’s interesting about the a7S III’s XAVC HS implementation is that it captures the same bitrate as the conventional XAVC S footage. The H.265 codec is more efficient than the older H.264 system, so the XAVC HS files should be able to retain more detail about the scene and movement within the scene in the same file size.

Meanwhile, there’s also an All-I variant of XAVC S. This is still based around H.264, but treats every frame as an ‘Intra’ frame: saving full information about it, rather than saving the differential information about what’s changed between more occasional ‘I’ frames. This is mainly valuable for encoding complex motion and detail in busy scenes.

It’s actually possible to capture All-I footage at 4K/120p but this can only be done without audio, via the S&Q slow-mo mode, which keeps the write-rate down to 240Mbps.

1080 video options

As with the original a7S camera, the Mark III’s 12MP can either be seen as a (give-or-take) native 4K sensor or as a sensor that provides perfect 2:1 oversampled 1080 footage. The same codecs and bitrates are available from a Super 35 crop. The cropped version isn’t oversampled.

Frame rates Bit-depth/ chroma Chroma sub-sampling Bitrate
(Mbps)
XAVC S
(H.264)
  • 120p
8-bit 4:2:0
  • 100
  • 60
  • 60p
10-bit 4:2:2
  • 50
8-bit 4:2:0
  • 50
  • 25
  • 30p
10-bit 4:2:2
  • 50
8-bit 4:2:0
  • 50
  • 16
  • 24p
10-bit 4:2:2
  • 50
8-bit 4:2:0
  • 50
XAVC S-I
(All-I H.264)
  • 60p
10-bit 4:2:2
  • 222
  • 30p
  • 111
  • 24p
  • 89

120p/100Mbps requires at least a V30-rated SD card. Boxes marked red require at least a V90 SD card. CFexpress cards can record all modes.

It’s worth noting that there’s no H.265 option for 1080 capture. Also note that All-I recording demands a CFexpress card or V90-rated SD card even for 89Mbps 24p capture, presumably because the camera needs to be certain it can clear its buffer.

Raw video output

As is the case on many recent cameras, the a7S II can output a Raw video stream for external recorders to then encode. Unlike most of its rivals, the Sony promises to output 16-bit data from its sensor.

Raw video output Sony a7S III
The camera has an HDMI v2.1 port allowing the fast data transfer to allow 16-bit Raw output.

Bit depth of Raw isn’t directly comparable to bit-depth of gamma-encoded data and doesn’t improve quality once you have sufficient data values to capture all the sensor’s dynamic range, so most cameras won’t show any benefit to offering more than 14-bit Raw.

However, with its large pixels, the a7S III could be the first camera we’ve seen where the the camera is capturing so much DR at a pixel level that it needs 16 bits to fully encode all that tonal range. This will be an interesting thing to explore once an external recorder offers support for the camera.

There’s no 16-bit mode for stills shooting.

Separable stills/video options

New to the a7S III is the ability to control which settings do and don’t carry across between stills and video. If you’re just grabbing quick clips it can be handy for settings like white balance to carry over from stills to video but if you’re trying to capture both types of media to a high standard, it’s common to require different settings. Separating the settings then lets you jump back and forth between stills and video shooting, without accidentally shooting Log stills or capturing video clips with 1/500 sec shutter speeds.

The menu option ‘Setup|Operation Customize|Different Set for Still/Mv’ lets you choose which of the following settings maintain different stills and video values:

Camera parameters that can be set to hold different values for
stills and video modes
  • Aperture
  • Shutter speed
  • ISO
  • Exposure comp
  • Metering mode
  • White balance
  • Picture Profile
  • Focus mode

HEIF stills capture

As well as JPEGs, the a7S III can also capture 10-bit compressed files using the HEIF format. This gives the option of 4:2:0 or 4:2:2 color subsampling. We’d recommend taking the 10% increase in file size to retain more color resolution (4:2:0 is something you usually only encounter in highly compressed JPEGs, in the stills world).

Interestingly, unlike Canon, the Sony doesn’t assume you’re using the move to 10-bit to record lifelike HDR images and will just use whichever color mode you were using for JPEGs. So, while there’s the option to shoot HDRTV-ready images using several variants of the Hybrid Log Gamma tone response (and these will work best in HEIF) you can also shoot 10-bit images with the Standard ‘Creative Look’ or if you wish. Or even S-Log for that matter.

Neither the EVF nor LCD is able to show HDR images but there is a choice of Gamma Assist modes to give you a more usable preview. You need to manually select the appropriate assist mode to match your current shooting mode.

Quad-channel audio

The a7S III has the ability to record up to four channel audio in its video, rather than just two. To do this it needs to be used with the XLR-K3M adapter. This features two XLR inputs and a 3.5mm stereo input (though the left and right channel of the 3.5mm input can’t be adjusted independently).

There’s an option in the Setup menu to select which inputs are output to the two monitoring channels. This includes the option to hear channels 1 and 3 in one ear and 2 and 4 in the other, for full four-channel monitoring.

How it compares:

The Sony a7S III may look a lot like other mirrorless full frame cameras (including being near-identical to the a7R IV), but its focus on delivering high-end video makes it most directly comparable to Panasonic’s Lumix DC-S1H.

We’ve included Sony’s a7 III here to show what you gain over a more mainstream camera and have included Canon’s EOS R5 for similar reasons: both these cameras are primarily aimed at stills shooters but appear to have strong video specs on paper.

Sony a7S III Panasonic Lumix DC-S1H Sony a7 III Canon EOS R5
$3500 $4000 $2000 $3900
Resolution 12MP 24MP 24MP 45MP
Sensor type BSI CMOS BSI CMOS BSI CMOS Dual Pixel (FSI) CMOS
Autofocus type Phase detect DFD (Contrast-based) Phase detect Dual Pixel (Phase detect)
Image stabilization Up to 5.5EV Up to 6.5EV Up to 5.5EV Up to 8EV
Burst shooting rate 10 fps 6.0fps with AF-C 10 fps 20 fps (e-shutter)
12 fps (mech)
Viewfinder 9.44m dots
0.90x mag
5.76M dots
0.78x mag
2.36M dots
0.76x mag
5.76M dots
0.76x mag
Rear screen 1.44M dots
Fully-articulating
2.3M dots
Tilt + Articulating
0.92M-dot
Tilting
2.1M dots
Full articulating
Full-frame video options
(Capture res and max frame rate)
UHD full-width (4.2K 60p)
UHD 1.1x crop
(4K 120p)

DCI/UHD Full Width
(5.9K 30p)
UHD full-width
(6K 24p)
UHD 1.2x crop
(5K 30p)
DCI/UHD 8K full width
(8.2K/7.7K 30p)
DCI/UHD 4K
full width
(8.2K/7.7K 30p)
DCI/UHD full width
(?/? 120p)
Super 35 video options
(Capture res and max frame rate)
Full HD
(1080 120p)
DCI/UHD
(4K 60p)
UHD
(4K 30p)
DCI/UHD 4K
(5.1K/4.8K 60p)
Raw video External
4K/60 16-bit
External
6K/24 12-bit (promised)
No Internal
8K/30 12-bit
(20 min)
Log modes S-Log2
S-Log3
V-Log S-Log2
S-Log3
C-Log
HDRTV modes HLG HLG No PQ
Highest quality codec 10-bit 4:2:2 H.265 XAVC HS 10-bit 4:2:2 H.265 8-bit 4:2:0
H.264
10-bit 4:2:2 H.264
All-I option 10-bit 4:2:2 H.264 XAVC S-I 10-bit 4:2:2 H.264 N/A 10-bit 4:2:2
H.264
Time limit >1 hour 4K/60p Unlimited 29:59 with thermal warning disabled 29:59 or thermal limit
Shooting aids

Peaking
Zebras
PDAF

Peaking
Zebras
Waveforms
Vectorscope
Peaking
Zebras
PDAF
Peaking
Zebras
Dual Pixel AF
Media formats Dual UHS-II / CFexpress A Dual UHS-II 1x UHS-II
1x UHS-I
1x CFexpress B
1x UHS-II
Other notes Up to 4 channel (with XLR adapter) Dual audio gain levels
TC sync
Battery life
LCD / EVF
600/510 400/380 610/710

490/320
Weight 699g 1164g 650g 738g
Dimension 129 x 97 x 81 mm 151 x 114 x 110 mm 127 x 96 x 74 mm 139 x 98 x 88 mm

II. Body, controls and handling

Sony a7S III - Body, controls and handling

Key takeaways

  • Redesigned menus with touchscreen operation
  • Large, high resolution viewfinder
  • Updated ergonomics from a9 II and a7R IV
  • Dual card slots that accept either SD or CFexpress Type A

EVF

The a7S III is the first camera to use a new 9.44M dot OLED EVF. That’s 2048 x 1536 pixel resolution: 27% higher in each direction than the 5.77M dot finders found in the best of its peers and literally twice the resolution in each dimension of the panel used in the a7S II.

Despite its high resolution, it can be run at up to 120 frames per second, giving an impressively lifelike view on the world. However, in its default mode it isn’t being driven at anything like its full resolution. Switching to ‘Display Quality: High’ boosts this but the preview still doesn’t look quite as detailed as playback mode.

In addition to its impressive resolution, the viewfinder has magnification of 0.91x, which means it’s very large. An eye-point of 25mm means you’re likely to be able to see to the corners of the display even with glasses on but there’s a ‘zoom out’ option that uses a smaller area of the screen if it’s not sufficient.

Articulating screen

The a7S III also has a fully articulating rear LCD: a first for an a7-series camera. It’s an oddly low resolution panel (1.44M dots) for a camera of this price, especially one in which the LCD is likely to be a primary means of interacting with the camera. But it’s touch sensitive to a much greater extent than previous Sony cameras, which we’ll cover further down the page.

Fourth gen’ ergonomics

Fourth gen' ergonomics sony a7s iii

Although it’s only the third a7S camera, the a7S III gets the much improved ergonomics introduced on the a7R IV. This means a more comfortable grip, large grippy joystick and prominent AF-On button. It also features the togglable lock on the exposure comp dial and the mode dial lock that needs to be pressed to turn the dial.

The camera also feels a little more responsive that previous Sonys we’ve used, making the connection between your button presses and the camera’s response feel more direct.

SteadyShot Active

In addition to all its other video features, the a7S III becomes the first Sony mirrorless camera to offer the SteadyShot ‘Active’ mode. This applies a slight (1.13x) crop to the sensor, which allows the mechanical IS system to make larger movements without risking vignetting.

The ‘Active’ mode is specifically designed for situations in which you’re moving with the camera: perhaps walking or on a vehicle with significant engine vibration.

Full-sized HDMI

full-sized hdmi sony a7s iii

In keeping with the serious video focus, the a7S III joins the likes of Panasonic’s S1H in offering a full-size HDMI connector. This is a much more durable connector that’s much less likely to drop the signal if anything touches the cable.

The camera comes with a fairly sizable screw-in cable retainer that slots over the top of the port doors. This protects the head of the HDMI lead and also secures the cable so that any pull on the cable is at right-angles to the socket. The design leaves all the other sockets accessible but limits the degree to which the screen can be flipped out.

Revised menus

Revised menus sony a7s iii

One thing that you won’t see on the spec sheets is that the a7S III has a totally re-designed menu system. Sony had already added better categorization and color coding to its menus before but this is a much more profound redesign.

To cope with the much more complex menus on a modern camera, the new menu system is based on a series of vertical tabs, which are then broken down into a series of sub-sections. It also shows the options within the current sub-section, so that you can see all the way down to individual options while retaining a clear picture of where you are in the overall structure.

Revised menus sony a7s iii

This is slightly undermined on ‘Shooting’ and ‘Setup’ tabs, where there are more than seven sub-sections, such that you can’t make an ‘at a glance’ assessment of all the possible categories of options, but generally the redesign will demand much less memorizing of the menu structure than before.

The underlying groupings of menu options remains consistent with the existing cameras, so existing Sony users should find themselves able to adapt pretty quickly.

More extensive use of touchscreen

Another area Sony has regularly been criticized for (by others as well as us) is the under-utilization of their touchscreens. The a7S III puts this right by letting you control both the Fn menu and main menus using the touchscreen.

Unfortunately an existing bugbear of ours persists: the tap-to-track setting that’s so useful for video persists into stills shooting (where it would be more useful to tap to set focus point). Still, at least it now defaults to tap-to-track, rather than you having to change a menu setting to activate subject tracking for video.

Dial customization

The a7S III is a three dial camera: front, rear shoulder, rear face with a dedicated exposure comp control, too. By default the front and rear top dials control aperture value and shutter speed (the order can be reversed). There’s also an option to put exposure comp on one of the top dials for Aperture Priority and Shutter Priority modes, if you wish.

The dial on the rear face does nothing by default but can have one of 12 functions assigned to it via the ‘Custom Key Setting’ menus (in the ‘Operation Customize’ section of the menu, not ‘Dial Customize’).

Actions assignable to dials
  • Audio Rec Level
  • Aperture
  • Shutter speed
  • ISO
  • Exposure comp
  • White balance setting
  • White balance K value
  • Creative Look
  • Move AF frame left/right [Std Increments]
  • Move AF frame left/right [Large increments]
  • Move AF frame up/down [Std increments]
  • Move AF frame up/down [Large increments\

If you really have strong ideas about what each dial should do, you can create ‘My Dials’ presets. These lets you assign any of the 12 assignable functions to any of the dials and create up to three different My Dial modes.

You need to configure a custom button to access these My Dials modes. This can either give direct access one of the My Dial presets (toggling or just when the button is held), or can cycle between presets.

Dual dual-format card slots

Dual dual-format card slots sony a7s iii

Sony has a long history of making card slots that could accommodate more than one media type, and the a7S III revives this tradition. However, rather than offering SD and Memory Stick compatibility, the Mark III becomes the first camera we’ve encountered to use the new CFexpress Type A format. Both slots can accommodate either UHS-II SD cards or CFexpress A cards.

CFexpress Type A are a new, smaller format introduced in V2.0 of the CFexpress standard. They use the same interface technology as the existing (XQD-like) CFexpress Type-B cards but with lower maximum read/write speeds. However, even though they’re not as quick as Type-B cards can theoretically become, they’re still quicker and offer larger maximum capacity than most UHS-II cards on the market (they’re based on the same technology as SD Express, which is two generations beyond UHS-II).

Battery

Battery sony a7s iii

As with autofocus, the Mark III sees the a7S series finally gain the bigger battery introduced to the rest of the range back in 2017. The 16.4Wh NP-FZ100 battery is rated for 600 shots per charge using the rear screen and 510 using the EVF. As always, CIPA numbers are broadly comparable between cameras but most photographers will find they get twice as many shots as quoted. A 600 shot rating is enough that it’s unlikely you’ll ever need to think about battery capacity when you’re shooting.

The USB-C port can also be used to charge or power the camera if used with USB PD compatible power sources. Note that it’s a case of power or charge: the battery does not charge while the camera is being operated using USB power.


III. Video testing

Key takeaways

  • Rolling shutter is impressive (sub 10ms) in all video modes
  • Readout rate is a fraction too slow to allow 120, hence the need for a slight crop
  • Sensor has a dual conversion gain design, switching over 4.66 EV above base ISO

Rolling shutter

The a7S III takes a different approach to the one used in more stills-focused generalist cameras: rather than taking advantage of a high pixel count sensor to give more detailed footage, the a7S III uses just a handful more than the bare minimum required to shoot 4K at all. The great advantage of this approach is that it has less data to read out. Which in turn means less risk of rolling shutter.

We measured the camera in a variety of modes, and the decision appears to pay off.

Video mode Rolling shutter rate
4K 60p / 30p / 24p 8.7ms
4K 120p 7.7ms
4K Steady Shot Active
(60p / 30p / 24P)
7.8ms

It’s worth noting that the rolling shutter rate for the full sensor width modes are a fraction short of the 8.3ms (1/120 sec) needed to shoot at 120 frames per second. This explains why a crop is needed to deliver 4K/120p but also why that crop doesn’t need to be too big.

Sub 10ms rolling shutter rates are generally considered excellent and will only begin to show visibly skewed verticals with very fast moving subjects.

We haven’t yet tested rolling shutter for the camera’s 16-bit Raw output mode. Sensors are able to read-out faster if they are sampling the data at lower bit-depths, so there’s the possibility that 16-bit mode will show more rolling shutter if the internal video modes are captured in 14-bit precision. We hope to check this week.

Dual Gain

As is common with modern large sensors cameras, the a7S III has a dual gain sensor. Sony doesn’t draw attention to this, either in its marketing or in the camera’s interface but most of its large sensors dating back to the original a7S have had a dual gain design.

As usual this means switching from the default, high dynamic range readout circuit in the pixel to a lower read noise (and lower DR) readout method for higher ISOs.

Because the ISO rating of each camera mode depends on the tone/gamma curve, the ISO value at which the switch is made depends on which Picture Profile you use. Our tests suggest the camera moves to its higher gain step 4.33EV above the base setting (the same amount above base the a7S and a7S II).

Base ISO 2nd gain step
Standard color
(Picture Profile Off)
ISO 80 ISO 1600
S-Log (2 or 3) ISO 640 ISO 12,800

As with previous Sony models, the camera doesn’t in any way acknowledge the switchover, but if you’re working near the ISO where the camera changes modes, you might be better-off moving up to the higher gain, lower read-noise state.


IV. Stills and video studio scene

Studio Stills

Our test scene is designed to simulate a variety of textures, colors and detail types you’ll encounter in the real world. It also has two illumination modes to see the effect of different lighting conditions.

The color mode option on the a7S III have been re-named ‘Creative Look’ but the default ‘Standard’ mode still looks pretty similar to the color response in previous Sony cameras. The change has been subtle with less magenta blues and both greens and yellows that look more like the Nikon response than that of the a7R IV. The addition of more magenta to the central pink target is the most significant difference and the biggest deviation from what otherwise appears to be a slight shift closer to the well-liked color responses Canon and Nikon have settled on.

Sony’s processing tends to be very good at sharpening subtle detail without overwhelming it, which allows the a7S III’s JPEGs to look similar to the downsized versions of its rivals’ output. But even at this ~10MP view, the a7R IV image retains more fine detail. As ISO values climb, the a7S III’s slightly lower noise levels combined with its effective, context-sensitive noise reduction arguably yield the most pleasing results, though some color blotches are apparent in portions of the image.

Viewing the Raw output at native size and it’s obvious how far behind 12MP lags, even when compared with 20 and 24MP cameras, in terms of detail capture. As theory would lead us to expect, the slight noise benefit to the a7S III’s larger pixels exists in the very deep shadows, so only have any impact at very high ISOs. You need to be working at extremes for the slight shadow noise benefit over the Z6 II’s 24MP sensor to appear, and even then the lower resolution of the a7S III is still visible.

Video stills

Our video stills grabs make it possible to assess the resolution and sampling method used to capture it.

It’s as a video camera the a7S III’s low pixel count offers a major benefit: few full-frame stills/video cameras this side of the Sony a1 can shoot 4K/60p from the full width of its sensor, and only the Sony pair currently capture 4K/120p from such a large sensor area. The lower pixel count means it’s capturing a touch less detail than the 24MP rivals, which oversample their 4K footage, but the a7S’s processing means there’s not much to call between the two. Of course it’s much less detailed than the 2X oversampled footage from the Canon EOS R5 (4K from 8K capture), but that’s famously difficult to deliver for extended periods of time.

The 120p footage isn’t quite as detailed as the full-frame capture, but it’s close enough to allow them to be intercut and still competitive against the output of similarly video-focused cameras


V. Video AF, dynamic range and Raw video

Video AF, dynamic range and Raw video sony a7s iii

Key Takeaways

  • Autofocus is adjustable and can be effective, but isn’t as powerful or dependable as Sony’s stills photography AF
  • 10-bit S-Log3 footage gives plenty of dynamic range, but not 15 useable stops
  • Raw output can be encoded as ProRes RAW by Atomos recorders but the footage requires more work for processing and the tools aren’t necessarily available to yield a major benefit over capturing 10-bit Log footage

Autofocus

A lot of pro and high-end videographers don’t use autofocus, primarily because it hasn’t always been very reliable and because there are well-established techniques of working without it. But that needn’t be the case forever. Every project will have its own standards of ‘good-enough,’ ranging from ‘ah, I’m sure no-one will notice’ all the way up to ‘perfect,’ and as autofocus gets more reliable, it’ll start to exceed that ‘good-enough’ threshold for more applications.

We’ve found the a7S III’s AF system to be pretty effective, in our shooting. It’s not quite as smart as the stills AF system, but gives you a good degree of control over how fast the focus is driven and how long the camera pauses before attempting to refocus.

The a7S III’s video AF system is pretty effective, but not quite as smart as the stills AF system

In order to access the camera’s tracking, you need to tap the rear screen (it won’t start tracking the subject under the AF point, so you can’t preemptively set your AF position). This will then track your subject and will use face or eye detection if you’ve got that mode engaged and will continue to track your subject even if they aren’t facing the camera.

This feels less dependable than the stills mode, and we’ve found it can occasionally start tracking the wrong thing after a while, but in our experience it’s usually pretty reliable and worth the risk of shaken footage that comes from the need to tap.

We’d recommend this way of working if you’re trying to get the camera to remain focused on people. There’s also the option just to let the camera focus on faces it’s found within the scene, which has the advantage that you don’t need to tap the screen, but because you haven’t specified the person as your subject, the camera may focus on something else if they look away.

Dynamic range

In terms of dynamic range, Sony says the a7S III can deliver up to 15 stops of dynamic range. But, while it’s true that the S-Log3 curve is designed to encode around 15 stops of information, it’s not necessarily the case that all of this is usable.

Dynamic range sony a7s iii

Here we’ve shot a brightness wedge with 13 stops in 1/3EV increments. As you can see, the darkest tones near the left-hand edge are extremely noisy (which would be the case even if the camera produced no noise at all). The rollover below lets you see the footage ungraded, then with Sony’s S-Log3 -> REC709 LUT applied, which pushes the shadow tones to a typical final-output level. We’ve then lifted the shadows in an exaggerated manner, to see whether there it’s possible to distinguish between the darkest steps.

Dynamic range sony a7s iii (1)

As you can see there’s a lot of noise in those darkest tones, even at base ISO, but there does genuinely appear to be some distinction between steps still. So, depending on your noise tolerance, it’s fair to say there’s a little more than 13 stops of DR available.

Raw video output

The a7S III is capable of outputting a Raw video stream of up to 60p over HDMI (the stream comes from the full sensor, wheres the camera has to crop-in slightly to deliver 120p). Sony says the stream is 16-bit but it’s not clear whether this comes from 16 or 14-bit sensor readout. Either way, the only current option to capture it is in the 12-bit ProRes RAW format using an Atomos external recorder.

We haven’t been able to get a clear answer on how that 16-bit signal is converted to ProRes RAW, and the lack of detail from Apple about the format makes it hard to predict what, if any, impact this conversion has. The camera lets you choose whether the output is treated as S-Log3/SGamut3 or S-Log3/CineGamut3, but we believe this only changes the metadata that tells the editing software (an NLE such as Final Cut Pro) how to initially render the file.

We’ll be looking in more detail at Raw video and how it relates to Raw in stills in a separate article, but one similarity that’s immediately apparent is how much processing the camera is doing on its compressed footage. Not only is the Raw footage presented as 4.2K resolution (4264 x 2408) rather than being downsized to UHD (3840 x 2160), it’s also had none of the fine sharpening, noise reduction or in-camera processing that the compressed footage has had applied to it. As such, the direct-from-recorder footage appears a touch soft and rather noisier than you might expect. This lack of processing lets you make decisions about these aspects in post, rather than in-camera, but the extra work needs to be anticipated if you’re planning to shoot this way.

For now, don’t expect easy access to the greater flexibility you get by shooting Raw instead of JPEGs as a stills photographer

Sadly, Sony does not appear to communicate sufficient metadata in its stream (or the software doesn’t understand it), to gain access to all of Final Cut Pro’s Raw video tools. The ‘ISO*’ pull-down for adjusting brightness and the dedicated Raw white balance options are not available. This immediately makes it a little more awkward to access the full flexibility of the Raw video and means you risk ending up with footage that’s akin to out-of-camera Log footage, but with more initial work that needs to be done.

We hope that Sony, Atomos or Apple is able to find a way to provide access to these tools (and more, as Raw video support matures), to make it easier to gain the full benefit of this way of shooting. For now, though, don’t expect easy access to all the greater flexibility you get by shooting Raw instead of JPEGs, as a stills photographer.

*This pull-down isn’t truly adjusting ISO, any more than the ‘Exposure’ slider in Raw processing software is retroactively changing the shutter speed and aperture you shot with, but then again the ISO standard doesn’t cover Raw, so don’t take any of it too literally.


VI. Conclusion

Conclusion sony a7s iii

What we like What we don’t
  • Excellent full-frame 4K footage at up to 60p
  • Only slight crop to 4K/120 mode
  • Excellent oversampled 1080 footage
  • 10-bit capture in H.265, H.264 or All-I H.264 gives workflow and grading flexibility
  • Log, HLG or Raw output options
  • Solid battery life
  • Choice of memory card format with most video recordable to SD or CFe
  • Nice viewfinder
  • Much-improved user interface
  • Option for HLG HDR photos using 10-bit HEIF format
  • Image stabilization, usable AF and good battery provides run-and-gun capabilities
  • Comfortable ergonomics
  • Full-sized HDMI socket
  • No out-of-camera DCI footage
  • Missing tools such as waveform display or shutter angle control
  • Video AF not quite effective as stills system and requires the screen to be tapped
  • 12MP stills appear low res, even at reduced sizes, compared with most modern cameras
  • Rear LCD isn’t especially detailed

I’ve primarily used the a7S III as a video camera. It’s clear both that video is where the bulk of Sony’s effort has gone and that there’s not a sufficient low-light benefit to make it worth spending this much money on a 12MP camera when less expensive models will produce more detailed images (even when downscaled to 12MP).

In spec terms, it’s obviously very impressive that such a small camera can reliably shoot 4K at 24, 30, 60 or 120p, without the need for a significant crop or loss of image quality. Those higher frame rates aren’t likely to be the core way of shooting, but the option to shoot 4K for 1/4 or 1/5 speed slow-mo is impressive. The perfectly oversampled 1080 is excellent, too. For most users, it’s the the ability to shoot all these modes in 10-bit and most of them in 4:2:2 with a choice of All-I or H.265 LongGOP that will be most useful: footage that’s very flexible, both from a grading perspective and in terms of workflow.

New Menus
We’ve found the revised menus much easier to navigate and less reliant on us memorizing where each setting can be found.

Beyond this, the greater emphasis put on heat dissipation and the much larger battery means you can rely on the Mark III to shoot for longer, in a way you can’t necessarily do with other a7-series cameras.

These higher-end capabilities raise our expectations for the camera. In particular it’s disappointing not to see waveforms on a camera that’s likely to be used as a standalone device. Similarly, if part of the a7S III’s appeal is its ability to switch between different frame rates almost seamlessly, why is there no option to view exposure in terms of shutter angle so that you don’t have to change shutter speed between modes?

Suddenly there’s a serious competitor to Panasonic’s S1H

These issues aside, the a7S III is hugely powerful producer of flexible footage supported by reliable autofocus, in-body stabilization and really solid battery life.

The 4K footage itself isn’t the most detailed – sampling roughly the same number of pixels as you plan to output isn’t a recipe for optimal detail, even before you factor-in the impact on color resolution of using a Bayer sensor – and we’re not convinced there are 15 usable stops of DR available, even in the Raw output. But Netflix’s approval of the DCI footage from the similarly-sensored FX6 suggest it’s more than good enough. Suddenly there’s a serious competitor to Panasonic’s S1H.

Compared to its peers

The Panasonic Lumix DC-S1H is one of the only stills/video cameras to take video anywhere near as seriously as the a7S III but It uses a very different approach: taking oversampled 4K video from a 24MP sensor, rather than adopting a ~4K sensor. This means its footage is more detailed than the Sonys but exhibits more rolling shutter and is limited to 30p unless you crop to Super35 mode, so it can’t match the Sony’s 60p and 120p ~full-frame capture. By contrast, though, the greater pixel count allows the S1H to offer anamorphic and open-gate 5.9K capture, which the Sony can’t match.

The S1H footage is more detailed than the Sonys but exhibits more rolling shutter

In addition, the S1H has features such as a waveform display, an option to control shutter angle, timecode sync and, in our experience, better image stabilization. It also has a fan-cooled design that allows a level of dependability that Sony doesn’t promise for the a7S III. That said, the Sony is smaller, has better battery life and much more usable autofocus, so it’s not a clearcut win for the Lumix. Our sense is that the more pro-friendly S1H might fit more happily alongside other, higher-end cameras, whereas the Sony makes more sense for smaller one- or two-camera production outfits.

Sony a7S III scoring

Scoring is relative only to the other cameras in the same category. Click here to learn about the changes to our scoring system and what these numbers mean.

Sony a7S III
Category: Professional Interchangeable Lens Camera / DSLR
Compare mode
Build quality
Ergonomics & handling
Features
Metering & focus accuracy
Image quality (raw)
Image quality (jpeg)
Low light / high ISO performance
Viewfinder / screen rating
Performance
Movie / video mode
Connectivity
Value
PoorExcellent
Conclusion
The Sony a7S III is a powerful video tool that can shoot 4K footage at up to 120p (up to 60p with no crop), in a variety of 10-bit formats to provide plenty of flexibility in terms of both grading and workflow. It has dependable autofocus, in-body stabilization and good battery life to boost its run-and-gun credentials. Its 12MP resolution means it’s less impressive as a stills camera but it’s a hugely powerful choice for independent video producers.
  • Good for
    Run-and-gun video, all manner of 4K productions
  • Not so good for
    Landscape photography

VII. Sample gallery

Sony a7S III sample gallery

Please do not reproduce any of these images on a website or any newsletter / magazine without prior permission (see our copyright page). We make the originals available for private users to download to their own machines for personal examination or printing (in conjunction with this review), we do so in good faith, please don’t abuse it.

Sony a7S III sample gallery

Sony a7S III 4K sample reel

We shot 4K video samples in both daylight and low light, and this sample reel includes examples all the way up to ISO 409,600.


VIII. Sony a7S III specifications

Sony a7S III specifications

Price
MSRP $3499 (body only)
Body type
Body type SLR-style mirrorless
Body material Magnesium alloy
Sensor
Max resolution 4240 x 2832
Image ratio w:h 1:1, 4:3, 3:2, 16:9
Effective pixels 12 megapixels
Sensor photo detectors 13 megapixels
Sensor size Full frame (35.6 x 23.8 mm)
Sensor type BSI-CMOS
Processor Bionz XR
Color space sRGB, Adobe RGB, BT.2020
Color filter array Primary color filter
Image
ISO Auto, 80-102400 (expands to 40-409600)
Boosted ISO (minimum) 40
Boosted ISO (maximum) 409600
White balance presets 7
Custom white balance Yes
Image stabilization Sensor-shift
Image stabilization notes 5-axis
CIPA image stabilization rating 5.5 stop(s)
Uncompressed format RAW
JPEG quality levels Extra fine, fine, normal
File format
  • JPEG (Exif v2.32)
  • HEIF
  • Raw (ARW 4.0)
Optics & Focus
Autofocus
  • Contrast Detect (sensor)
  • Phase Detect
  • Multi-area
  • Center
  • Selective single-point
  • Tracking
  • Single
  • Continuous
  • Touch
  • Face Detection
  • Live View
Autofocus assist lamp Yes
Manual focus Yes
Number of focus points 759
Lens mount Sony E
Focal length multiplier 1×
Screen / viewfinder
Articulated LCD Fully articulated
Screen size 3
Screen dots 1,440,000
Touch screen Yes
Screen type TFT LCD
Live view Yes
Viewfinder type Electronic
Viewfinder coverage 100%
Viewfinder magnification 0.91×
Viewfinder resolution 9,440,000
Photography features
Minimum shutter speed 30 sec
Maximum shutter speed 1/8000 sec
Exposure modes
  • Program
  • Aperture priority
  • Shutter priority
  • Manual
Built-in flash No
External flash Yes (Multi-interface shoe)
Flash X sync speed 1/250 sec
Drive modes
  • Single
  • Continuous
  • Self-timer
  • Bracketing (AE/WB/DRO)
Continuous drive 10.0 fps
Self-timer Yes
Metering modes
  • Multi
  • Center-weighted
  • Highlight-weighted
  • Average
  • Spot
Exposure compensation ±5 (at 1/3 EV, 1/2 EV steps)
AE Bracketing ±5 (3, 5 frames at 1/3 EV, 1/2 EV, 2/3 EV, 1 EV steps)
WB Bracketing Yes
Videography features
Format MPEG-4, XAVC S, XAVC HS, XAVC S-I, H.264, H.265
Modes
  • 3840 x 2160 @ 120p / 280 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 100p / 280 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 60p / 200 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 50p / 200 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 30p / 140 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 25p / 140 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 24p / 100 Mbps, XAVC HS, MP4, H.265, Linear PCM
  • 3840 x 2160 @ 60p / 600 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 50p / 500 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 30p / 300 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 25p / 250 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 24p / 240 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 120p / 280 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 100p / 280 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 60p / 200 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 50p / 200 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 30p / 140 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 25p / 140 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 3840 x 2160 @ 24p / 100 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 60p / 222 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 50p / 185 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 30p / 111 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 25p / 93 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 24p / 89 Mbps, XAVC S-I, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 120p / 100 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 100p / 100 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 60p / 50 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 50p / 50 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 25p / 50 Mbps, XAVC S, MP4, H.264, Linear PCM
  • 1920 x 1080 @ 24p / 50 Mbps, XAVC S, MP4, H.264, Linear PCM
Microphone Stereo
Speaker Mono
Storage
Storage types Dual SD/CFexpress Type A slots
Connectivity
USB USB 3.2 Gen 1 (5 GBit/sec)
USB charging Yes (USB PD supported)
HDMI Yes (Standard)
Microphone port Yes
Headphone port Yes
Wireless Built-In
Wireless notes 802.11ac (dual band) + Bluetooth
Remote control Yes (wireless or smartphone)
Physical
Environmentally sealed Yes
Battery Battery Pack
Battery description NP-FZ100 lithium-ion battery charger
Battery Life (CIPA) 600
Weight (inc. batteries) 699 g (1.54 lb / 24.66 oz)
Dimensions 129 x 97 x 81 mm (5.08 x 3.82 x 3.19)
Other features
Orientation sensor Yes
GPS None

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