Sony has expanded its full-frame Alpha 7 range, introducing the Sony A7 III, price tag £2000, which boasts a new backside-illuminated, 24-megapixel sensor and 4K video recording with S-Log.
At the heart of the Sony A7 III is a new 24.2-megapixel, back-illuminated Exmor R CMOS image sensor offering 15 stops of dynamic range at low sensitivities. The new Sony camera offers a native ISO range of 100 to 51,200, which you can expand down to ISO 50 or up to ISO 204,800.
The A7 III was long-rumoured to share the same chip as the A9, but Sony has confirmed it’s not the same stacked sensor as in the A9.
The Sony A7 III sensor doesn’t have onboard memory; however, there is a front-end LSI which Sony says doubles the readout speed from the sensor. This should improve autofocus speed and image quality through the application of better noise reduction algorithms.
Something the A7 III does inherit from the Sony A9, though is its autofocus system.
The Sony A7 III boasts 693 phase detection AF points which provide coverage for 93% of the image area, just like the A9. What’s more, it also features 425 contrast AF points and adds new 4D FOCUS functionality.
New in the A7 III is an Eye AF feature, which works even in continuous AF mode and can be used, Sony says, when your subject is turning around, looking down or obstructed.
Sony says it has also boosted the A7 III’s focusing speed, making it 2x faster in low light. Tracking is also 2x faster than the A7 II.
The Sony A7 III’s speed enhancements are down to a new BIONZ X image processing system that makes the A7 III nearly twice as fast as the A7 II.
This enables the camera to shoot full resolution images at up to 10fps in burst mode for up to 177 JPEGs, 89 compressed raw images or 40 uncompressed raw files.
The Sony A7 III can also shoot up to 8fps continuously in its live view mode.
And while the camera is writing these burst images to your memory card, Sony says you can access key functions and image playback menus.
The revamped processor gives the A7 III a 1.5-stop improvement in image quality, Sony says.
There is also an Anti-flicker mode that enables the A7 III to detect the frequency of the lighting and time the shutter accordingly to reduce its effect on your images.
The Sony A7 III can record 4K video (3840×2160 pixels) using full pixel readout without pixel binning binning to collect about 2.4x the amount of data required for 4K movies, and then over-samples it to produce high quality 4K footage. Sony adds:
An HLG (Hybrid Log-Gamma) picture profile is available on the α7 III as well, which supports an Instant HDR workflow, allowing HDR (HLG) compatible TV’s to playback beautiful, true-to-life 4K HDR imagery. Further, both S-Log2 and S-Log3 are available for increased colour grading flexibility, as well as Zebra functionality, Gamma Display assist and proxy recording. The camera can also record Full HD at 120 fps at up to 100 Mbpsvi, allowing footage to be reviewed and eventually edited into 4x or 5x slow motion video files in Full HD resolution with AF tracking.
So what does this mean in layman’s terms?
The Sony A7 III can record 4K video (3840×2160 pixels) using full pixel readout without pixel binning.
Pixel binning is surrounded by an incredible amount of complicated explanations, and unfortunately, there’s a good reason why. It is complicated, but let’s try to break down precisely what pixel binning is and why avoiding it is so good.
Before we start, we need to look at the very start of your images journey through the camera, and that starts with the sensor. The pixels on a camera’s sensor should really be called photosites or photoreceptors, we’ve just kind off slipped into calling them pixels.
These sensor pixels are known as photosites, and each is covered by a filter that only lets through one colour, either red, green or blue.
These photosites are laid out in what’s known as a Bayer Pattern that is unless it’s Fuji. In a Bayer pattern, every other pixel is green with alternate red and blue.
Some 50% of the sensor is therefore green, and the rest of the photosites are evenly split between the other two colours.
If this sensor captured image was to be shown directly it wouldn’t look good, so a process called Demosaicing is used to combine the R, G, G, B pixels into a single output pixel.
This selection of output pixels is the final resolution that we see in the final image. But what happens when the image we want is smaller than that produced by the sensor as is the case when we film at 4K or 1080p.
Somewhere along the line, some of those pixels need to be binned. This is where pixel binning comes in. In a full resolution image pixels are gathered, for example in a 2×2 grid (2 green, one blue and one red) and output as a single pixel.
When pixel binning comes into play, a 3×3 grid is output as a single RGB output pixel or even a 4×4 grid, and so it goes on. The process is pretty crude, but it is effective.
It now appears that the A7 MKIII is capable of capturing 2.4x the resolution needed to produce a 4K movie. This means that rather than binning those addition pixels the sensor is scanned at full resolution and then oversampled to produce high-quality 4K footage.
The oversampling method hasn’t been used widely in the past due to the processing power that’s required by the camera but has been seen in other Sony cameras such as the RX10.
What is the oversampling method – again it’s complex.
This is impressive stuff and will help ensure the best possible quality footage.
The A7 MKIII also features a range of picture profiles that will appeal to pro videographers. These modes for most of us will just produce flat, dull video that will instantly make us think that we’ve done something wrong.
In reality, these picture modes supply footage that contains more tone and dynamic range, similar to a raw file in still photography.
These modes include HLG (Hybrid Log-Gamma), which supports an Instant HDR workflow, allowing HDR (HLG) compatible TV’s to playback beautiful, true-to-life 4K HDR imagery.
You also get the more common S-Log2 and S-Log3 which are available for increased colour grading flexibility.When it comes to filming, you have Zebra functionality to check exposure clipping, Gamma Display assists and proxy recording.
The camera can also record Full HD at 120 fps at up to 100 Mbpsvi, allowing footage to be reviewed and eventually edited into 4x or 5x slow-motion video files in Full HD resolution with AF tracking.
Sony says battery life has also been greatly improved. It claims the A7 III has the longest battery life of any mirrorless camera, thanks to its NP-FZ100 battery, which enables it to record 710 shots on a single charge.
On the body are 11 custom buttons that can be used to access 81 functions, and its construction is dust and moisture resistant.
A 2.3-million-dot XGA OLED Tru-Finder offers Standard or High display quality settings.
Other features include dual SD card slots, SuperSpeed USB 3.1 Type-C terminal and a joystick for adjusting AF points.
Sony A7 III Price & Release Date
The Sony A7 III price tag is £2,000 / €2300 for the body only. The A7 III price tag rises to £2200/ €2500 in a kit with the SEL2870 lens.
The Sony A7 III release date will be in March 2018.