The Sony a7R Mark III is the company's latest high-resolution full frame mirrorless camera. Much like Nikon's recent D850, it's one that combines this resolution with high speed and fast autofocus capabilities to a degree we've not previously seen.
Like its predecessor, the Mark III is built around a 42MP BSI CMOS sensor, but unlike the a7R II, it can shoot at ten frames per second.
Essentially it can be seen as an a7R II that inherits many of the lessons learned from the company's pro-sports model, the a9. This means faster processing, improved autofocus, improved handling and ergonomics, as well as the adoption of a much larger battery. While some of the individual changes are subtle, they very quickly combine to produce a hugely capable and highly useable camera.
42MP BSI CMOS sensor
Faster, lower-noise image processing
10 fps shooting with full AF, 8 fps with 'live' updates between shots
3.69M dot (1280 x 960 pixel) OLED viewfinder
Improved autofocus, including more tenacious Eye AF mode
5-axis image stabilization, rated at 5.5 stops (CIPA) with 50mm lens
4K footage from 'Super 35' crop region oversampled from 5K capture
Video AF less inclined to refocus to background
'Picture Profile' video gamma/gamut modes including S-Log2 and 3
Twin SD Card slots (one UHS-I and one UHS-II compatible)
Bayer-cancelling multi-shot mode for improved resolution
True 14 bit uncompressed Raw, even in continuous drive mode
Use of phase detection (including Eye AF) at 3 fps with adapted lenses
Sony says the a7R III is based around the same 42MP back side illuminated CMOS sensor as its immediate predecessor, so doesn't gain the full speed advantages of the a9's Stacked CMOS chip (in terms of AF performance, continuous shooting rate or reduced rolling shutter in video and electronic shutter mode). However, the adoption of the processing systems, algorithms and refinements introduced on the a9 all have their benefits.
This means a camera with a touchscreen and dedicated joystick for AF point positioning, a camera with a deeper grip and improved customization, with better laid-out menus and much improved battery life.
Sony also says the improved processing will benefit video shooting. The oversampled footage taken from a Super 35 (~APS-C) region of the sensor is still expected to look better than the subsampled capture from the full sensor width but both are supposedly improved by the new processing chain. We'll delve into this later in the review.
To take advantage of the camera's dynamic range, the Picture Profile system of color and tonal response borrowed from Sony's professional video line now includes the even flatter S-Log3 gamma curve. That said, there is no 10-bit capture possible; the camera can still only capture 8-bit 4:2:0 footage internally or output 8-bit 4:2:2, which may limit the usefulness of S-Log3 if it makes posterization more likely when the footage is graded.
For users wanting to use the camera's video dynamic range with a high dynamic range display but without the extra hassle of color grading, the a7R III joins the Panasonic GH5 in offering Hybrid Log Gamma recording: essentially Log capture with tags to tell displays how to correctly render it.