Introduction

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.

Key Features

  • 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.

Video capabilities

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.

Compared:

The a7R III's most obvious peer is the D850, since it's the other high-speed, high resolution full frame camera. We'll also note the changes relative to its predecessor and its other, less rapid high-res rivals.

Sony
a7R III
Nikon D850 Sony
a7R II
Canon EOS 5DS R Pentax K-1
MSRP
(Body only)
$3200 $3300 $3200 $3900 $1800
Pixel Count (MP) 42.4 45.7 42.4 50 36
Sensor type BSI-CMOS BSI-CMOS BSI-CMOS CMOS CMOS
ISO Range 100-32,000 64-25,600 100-25,600 100-6,400 100-204,800
Stabilization In-body
(5.5 stops)
Lens-only In-body
(4.5 stops)
Lens-only In-body
(5 stops)
AF working range –3EV (@F2) –4EV –2EV (@F2) –2EV –3EV
Viewfinder magnification & eyepoint 0.78x
23mm
0.75x
17mm
0.78x
23mm
0.71x
21mm
0.70x
21.7mm
Connectivity options Wi-Fi, BT
(+NFC)
Wi-Fi, BT Wi-Fi
(+NFC)
Optional SD Card Wi-Fi
Video 4K/30p
1080/120p
4K/30p 4K/30p
1080/120p
1080/60p 1080/30p
Mic/
Headphone
Yes / Yes Yes / Yes Yes / Yes Yes / No Yes / Yes
Flash sync speed 1/250th 1/250th 1/250th 1/200th 1/200th
Flash Sync socket Yes Yes No Yes Yes
Continuous shooting 10fps 7fps* 5fps 5.0fps 4.4fps
Intervalometer No Yes Via app Yes Yes
Memory format SD (UHS-II)
SD (UHS-I)
XQD
SD (UHS-II)
1x SD (UHS-I) CF (UDMA)
SD (UHS-I)
2x SD
(UHS-I)
USB (Connector) 3.1 (C)
2.0 (micro B)
3.0 (micro B) 2.0 (micro B) 3.0 (micro B) 2.0 (micro B)
Battery life (CIPA)
VF/LCD
530/650 1,840/ - 290/340 700/200 760/ -
Weight 657g
(23.2oz)
1005g
(35.5oz)
625g
(22.0oz)
930g
(32.8oz)
1010g
(35.6oz)
*D850 can shoot 9fps when combined with a battery grip and D5-style battery.

As should be apparent, the Sony offers a combination of resolution, speed and video capabilities not easily matched by its peers. And, with the new battery, is able to offer much more similar endurance, if you're not in a situation in which you can plug the camera in to an external power source.