This could easily get confusing, so let’s do a quick stocktake of Sony’s A7 mirrorless camera range.
While the A7 III is the eighth A7 model to be announced, in reality there are just three A7 product lines. The A7 line is the basic all-round option, the A7S series is a lower-resolution, higher-speed action and video specialist. The A7R, meanwhile, is the flagship, high-resolution model for photographers who want the ultimate in quality.
So what Sony is doing is continually updating each of these three main camera lines with new versions. The A7S series is still at the Mark II stage, while the A7R has already reached Mark III (which we reviewed here). And now, the basic A7 line gets upgraded to a Mark III option.
We say ‘basic’, but this camera is a long way from that. The A7 III might be the affordable entry point into Sony’s A7 full-frame mirrorless range, but the technology and features in Sony’s new camera practically put it in a league of its own.
In fact, when we came to choose three rivals to put against it, there were none that came close to its combination of a full-frame sensor, 4K video, 10fps shooting or even the sophistication of its autofocus system without spending two or three times more.
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Sony has really stirred up the professional full-frame camera market with its A-series mirrorless cameras, luring many pros away from Canon and Nikon DSLRs into the brave new world of mirrorless imaging. For an asking price a whisker under £2,000/$2,000, the A7 III is probably Sony’s most compelling DSLR alternative – and not just for professionals, but keen enthusiasts too.
- Sensor: 24.2MP full-frame Exmor R CMOS, 35.6×23.8mm
- Image processor: BIONZ X
- AF points: 693-point phase-detection AF / 425-point contrast-detect AF
- ISO range: 100-51,200 (expandable to 50-204,800)
- Max image size: 6,000 x 4,000
- Metering zones: 1,200
- Video: 4K UHD at 30/24fps, Full HD at up to 120fps
- Viewfinder: XGA OLED type, 2,359,296 dots
- Memory card: 2x MS/SD/SDHC/SDXC (1x UHS-II)
- LCD: 3in tilting touchscreen, 921,600 dots
- Max burst: 10fps (177 JPEGs, 89 compressed RAW, 40 uncompressed Raw)
- Connectivity: Wi-Fi, NFC, Bluetooth
- Size: 126.9 x 95.6 x 73.7mm
- Weight: 650g (with battery and memory card)
Just like its predecessors, the A7 II and the A7, the A7 III has a 24MP sensor. Resolution is probably the first thing camera buyers look for, and it's perhaps this camera’s most unremarkable specification. It’s not the same sensor as before, however; this one has a back-illuminated design for improved light-gathering, and is teamed up with a front-end LSI and BIONZ X processor that produce much faster data readout and processing speeds than before.
The end result is much improved noise and high ISO performance, high-quality 4K video and that impressive 10fps continuous shooting speed – double the speed of the previous A7 II.
High-speed shooting isn’t much good without a buffer capacity to match, and while the A7 III can’t compete with sports specialists like the Canon EOS-1D X Mark II or Nikon D5, it has a bigger buffer than the average enthusiast camera. It's capable of capturing up to 177 JPEGs, 89 compressed Raw files or 40 uncompressed Raw images in a single burst.
One criticism of previous models is that once the buffer is filled you can’t use the camera menus until it’s cleared – but Sony has fixed that with the A7 III. You may also find that the viewfinder image at 10fps isn’t quite responsive enough for following fast or erratic subjects, but there’s an 8fps ‘live view’ mode that offers a faster, more stable viewfinder image.
To get 10fps shooting in a full-frame camera at this price is remarkable, but Sony has gone a step further by incorporating the autofocus technology from its flagship A9 sports camera. With 693 phase-detection AF points covering 93% of the image area, backed up by a further 425 contrast-detect AF points, this is, on paper, just about the most powerful AF system on the market.
You can choose from Wide-area AF, Zone AF, Centre AF, Flexible spot mode (in which you can change the size of the AF area) and now Expand Flexible Spot mode, where the camera will still stay focused on subjects that stray outside the selected area. There’s an Eye AF mode for portrait photographers too, and on the A7 III this now works in continuous as well as single-shot AF modes.
There's also a sensor-based 5-axis image stabilisation system, with its claimed 5-stop shake compensation, together with twin memory card slots (though only one of these is UHS-II compatible).
The battery can be charged in-camera via a USB cable or, for faster charging, there’s an optional BC-QZ1 battery charger. This new battery, the NP-FZ100, has 2.2 times the battery life of A7 II’s NP-FW50, yielding 710 shots on a single charge (or 610 when using the electronic viewfinder).
And the A7 III is not done yet. As we’d expect from any new Sony camera, the A7 III shoots 4K video, but it brings instant 4K HDR playback on compatible devices via its HLG (Hybrid Log-Gamma) profile, and also has Sony’s S-Log3 mode for increased dynamic range (up to 14EV) for editing/grading later. 4K video is captured across the full sensor width, before being downsampled to 4K resolution, so there are no annoying crop factors and no inefficient pixel binning.
If we listed every single thing this camera has, or does, or is capable of, there would be no room left to say whether it’s any good or not – which is the next bit.