The Sony a7R III ($3,199.99, body only) uses the same sensor as the a7R II that came before it, but just about everything else has changed.
The image processor and circuitry that drives it are new, which improves dynamic range.
The processor also drives a new autofocus system, which allows the camera to track moving action at 10fps—at 42MP resolution.
Add a high-capacity battery, improved handling, and a larger viewfinder, and you have a full-frame mirrorless camera that is as formidable as competing SLRs.
It delivers outstanding images, video, and autofocus, enough to earn our Editors' Choice.
But some missing features keep it from getting the five-star rating we gave to its closest rival in the SLR world, the Nikon D850.
Note: This review has been updated to reflect changes in the a7R III added by its Firmware 3.0 release.
Design
The a7R III ($2,298.00 at Amazon) looks and feels a lot like the a7R II—they use the same chassis.
It measures 3.8 by 5.0 by 2.9 inches (HWD) and weighs 1.5 pounds.
The body is protected against dust and splashes, as are all Sony FE lenses.
There are a few physical changes, notably touch sensitivity on the LCD, a larger EVF, a dedicated focus selector (like you get with the a9), dual memory card slots, and a higher capacity battery.
But if you've picked up and used any of the Mark II models—including the a7 II and a7S II—you'll feel right at home with the a7R III.
Most of the control you want is right at your fingertips.
The body eschews front buttons, save for a dial integrated into the handgrip, instead putting its buttons and dials on the top and rear.
You don't get the drive and focus mode selector dial like you do on the a9—which is a shame, as it's quite useful.
The top plate houses, to the right of the hot shoe, a locking Mode dial, C1 and C2 buttons (both customizable), and a dedicated EV dial with third-stop adjustments from -3 to +3 EV.
The power switch surrounds the shutter button and sits atop the handgrip, just ahead of C1 and C2.
The top is unchanged from the a7R II—as with others in the series, there's no built-in flash.
On the rear we see some control changes.
The C3 button has moved to the far left top corner, with the Menu button in its familiar place to its right.
The top row of controls aren't at as steep of an angle as they are on the a7R II, so they're a bit easier to access.
This is a design cue inherited from the a9.
There are more changes as you look to the right of the EVF and rear display.
The Record button is in the familiar place, just to the right of the EVF, and is surrounded by a raised ridge so you're not likely to press it accidentally.
Next to it are dedicated AF-ON and AEL buttons.
AEL was included on the a7R II, but it was in a different position.
AF-ON, which can be used to drive the focus system independently of the shutter release, is a feature that many pros love, and I'm happy to see it here.
The rear command dial is slightly higher than the AF-ON and AEL buttons, and is positioned between them.
The a7R III finally has a dedicated control to adjust the autofocus area.
This is a godsend if you prefer to use a flexible spot for focus.
It's in the same spot that you find it on the a9, taking the place of the a7R II's combined AF/MF/AEL control.
Below it, you find the Fn button, a control dial with a center button and four directional presses; Display, Drive Mode/Self Timer, and ISO are marked on the body, but as with most of the buttons, they're customizable.
Finally, you get Play and Delete/C4.
The rear LCD supports touch input.
This is a first for the a7 series, and a feature we're finally seeing on almost every new professional camera.
You can tap to select a focus point (assuming you're not in a wide focus mode), although this won't immediately change the focus.
Touching a part of the frame does automatically rack focus when recording video.
The display itself is 3 inches in size and packs a 1,440k-dot resolution, a modest bump from the 1,228k screen used by the a7R II.
The EVF is also upgraded, and it's a more substantial jump.
The new finder maintains the high 0.78x magnification, but is sharper at 3.6 million dots, up from 2.4 million.
It's one of the best you'll find in any mirrorless camera.
Power and Connectivity
The a7R III ditches the FW50 battery used by previous models.
It opts for the newer FZ100 battery introduced in the a9.
The larger battery has more than double the capacity.
According to CIPA standard testing, the battery is good for about 650 images using the rear LCD and 530 with the more power-hungry EVF.
CIPA rates are generally pretty accurate for single-drive shooting, but if you utilize burst you'll likely get more shots.
In one shooting session I captured close to 1,000 Raw+JPG images along with about 10 minutes of 4K video and only burned through about half of the battery.
Those figures include heavy use of the 8fps and 10fps capture options, however.
We shouldn't understate the importance of a big, reliable battery.
The FW50 battery used by older a7 models just doesn't provide enough juice for a professional to use it to cover an event without having to plan for a battery change (or two) during the course of the gig.
If you're documenting a wedding you have too many things to worry about already; finding a break in the action to change a battery is an unwanted distraction.
For more operating time, the a7R III supports a vertical shooting grip that holds two batteries, effectively doubling the number of shots you'll get before making a change.
The camera ships with an external battery charger, but can also charge internally, and has two ports to support this.
One is the long standard micro USB, the other is the more modern USB-C, with support for faster transfer speeds.
The USB ports are also used for tethered shooting.
Sony has a new software package to support tethered capture and Raw conversion, available for Mac and Windows systems.
Other ports include PC Sync for external flash, 3.5mm microphone and headphone, and micro HDMI.
There are dual memory card slots, both with support for SD, SDHC, and SDXC media.
You'll need to use a U3 card to take full advantage of video features, and I recommend investing in high-speed UHS-II memory if you plan on utilizing burst image capture.
Only one slot is UHS-II compliant, the same as with the a9.
I still think that's a poor choice on Sony's part.
The UHS-I SD slot is also compatible with Memory Stick media.
The a7R III features Sony's latest cocktail of wireless communication, which includes Bluetooth, NFC, and Wi-Fi.
It works just as it does with the a9.
Bluetooth is used to set the camera's clock, keep a connection to your phone alive for quicker pairing, and add GPS data to images, based on your phone's GPS.
NFC will launch the Sony PlayMemories Mobile app on compatible devices, and Wi-Fi is used for image transfer and remote control.
PlayMemories Mobile is available for Android and iOS.
The a7R III didn't have an in-camera intervalometer for time-lapse capture at launch, but one was added via the Firmware 3.0 update.
It can be set to take images at set intervals for time-lapse capture.
It's limited to saving individual images—in Raw or JPG format—and the a7R III's sensor has enough pixels to output time-lapse footage at close to 8K resolution.
Sony's menu system is quite dense, with pages and pages of options, not all of which are easy to understand.
The addition of a customizable My Menu page is a welcome one, but you'll still want to spend a couple hours configuring the camera to your liking when you first get it.
Performance and Autofocus
The a7R III isn't Sony's fastest full-frame mirrorless camera.
That's the a9, released a few months ahead of the a7R III.
I've talked about the a9 here simply because that's where a lot of the upgraded technology powering the a7R III was introduced.
The two models handle burst shooting differently.
The a9 shoots at 20fps with focus tracking, but only with its electronic shutter.
Its 24MP sensor is able to acquire and process data fast enough to allow for this, while eliminating the pitfalls you get with electronic shutters with slower readout—notably distortion caused by the rolling shutter effect and banding, which can be created by certain artificial light sources.
It can't sync with flash, however, you need to switch to the mechanical shutter for that—and when you do, the a9 becomes a 5fps camera.
The a7R III has a brand new mechanical shutter, designed to minimize vibration, while at the same time supporting 10fps capture with 1/250-second flash sync speed.
With strobes that are capable of firing that quickly you'll be able to shoot fast-moving action in the studio.
Sony put together a shooting event at Shop Studios in New York to showcase the capability.
The images above, two sequential shots from a 10fps burst sequence, are an example of how you can use the a7R III to freeze motion and capture intense action in a studio situation.
It's able to track subjects at such a high rate thanks to its on-sensor autofocus system.
A mix of 399 phase detect and 425 contrast points cover about 68 percent of the sensor area, with the central 47 percent covered by phase.
It's not as insane as the a9, which covers 93 percent of its sensor, but it's a larger focus area than you'll find on any full-frame SLR.
In use, the a7R III is extremely responsive.
It requires a couple of seconds, 1.9 in tests, to start, focus, and take a shot, just a little bit longer than the a9 (1.6 seconds).
The autofocus time is nearly instant, 0.05-second in bright light, although it slows to about 0.15-second in dim conditions.
Both figures are quicker than the a7R II, which requires about 0.2-second to focus in bright light and 0.7-second in very dim conditions.
Those numbers translate to real-world use—the a7R III is very noticeably faster to lock focus and fire compared with the a7R II.
See How We Test Digital Cameras
Burst shooting speed hovers around 10fps, regardless of what format you use.
How long the camera can keep that pace varies based on what type of files you're shooting and how fast your memory card is.
When paired with a Sony 300MBps card I netted 30 uncompressed Raw+JPG or uncompressed Raw images at a time.
Clearing a full burst to memory requires 22.6 seconds for Raw+JPG and 18.7 seconds for Raw.
Switching to compressed Raw or to JPG-only capture extends the shooting duration.
I got 81 Raw+JPG shots with compression on, 82 Raw+JPG, and 82 JPGs before the buffer filled up and capture stopped.
Write times are longer—39.6 seconds for Raw+JPG, 38.3 seconds for JPG, and 23.8 seconds for Raw.
In any event, you don't have to wait for the buffer to fully clear to start shooting again—it's possible to start filling it up again as it clears to the card.
What you can't do is start a video recording while images are being written to the card, which can be frustrating when going back and forth between still and video capture.
The 10fps rate is maintained when shooting in AF-C mode.
The a7R III is extremely effective in tracking moving subjects.
Quick acquisition, excellent subject recognition, and the advantages of on-sensor focus all come into play here.
It doesn't match the a9's uncanny ability to track at 20fps, so the a9 is still the better choice for situations where extra speed is needed.
But for most photograpy, 10fps is ample.
There are a number of autofocus modes available.
I tend to swap between the Wide setting, which automatically chooses what to focus on, and the Flexible Spot, which restricts focus to a specific area.
Flexible Spot is more useful on the a7R III than on previous iterations of the camera for shooting action thanks to the small focus joystick—it's very easy to move the point around.
The Firmware 3.0 update changes the way one of the a7R III's big autofocus features, Eye AF, works.
Instead of having to press a separate button to identify eyes, the camera now does it automatically.
As long as the eye is covered by the current autofocus area, and it's large enough for the camera to identify, the a7R III will focus on it.
If the eye isn't large enough to see, the camera falls back on face detection.
[embed]https://www.youtube.com/watch?v=E_ECESoU3HI[/embed]
In addition to humans, the new firmware also adds support for certain animals.
Officially cats and dogs are supported.
We tested the feature and found it to work quite well.
It had some issues identifying eyes when a pet was in profile, but aside from that, we have few complaints.
You can see Eye AF at work in the clip above, recorded from the a7R III's micro HDMI output port.
Like the a9, the a7R III has a fully electronic shutter option.
It allows for silent shooting, which is a plus for covering weddings and events, as well as for wildlife photography.
It also completely removes shutter vibration from an image, which can make a difference when working with such a high-resolution sensor.
But because it doesn't have the same incredibly fast sensor readout, banding and rolling shutter are a concern.
If you're shooting under certain types of artificial light, or capturing fast-moving action, it's better to use the mechanical shutter.
Imaging
The a7R III uses the same full-frame 42MP BSI CMOS sensor as its predecessor.
Sony states that improved circuitry and image processing deliver improvements in image quality.
Notably, the Raw dynamic range is rated at 15 stops, up from 14.
The a7R II already delivered Raw output that made it possible to pull details out of shadows, without increasing noise, in an almost frightening manner.
And no one has ever complained about a bit of extra leeway in exposure adjustment.
To get an idea of how much detail you can pull from shadows, take a look at the images above; the one on the left doesn't include any shadow adjustment, while the one on the right has shadows and black raised to show detail.
The in-body image stabilization is also slightly improved.
The 5-axis sensor-based stabilization system is now rated to compensate for 5.5 stops of shake, up from 5 stops.
The added precision isn't just used to ensure images are as sharp as possible, however.
Sony is using it to implement its own high-resolution pixel shift capture system.
We've seen this type of system in Olympus mirrorless models and the Pentax K-1 SLR previously.
Sony's take, Pixel Shift Multi Shooting, is similar to Pentax's.
When using that mode the a7R III...
