Sony a9 III review in progress: Digital Photography Review

The Sony a9 III is the company’s latest high-speed pro sports camera. It features a Stacked CMOS sensor capable of shooting at 120 fps and able to read all its pixels out simultaneously: the long hoped-for ‘global’ shutter.

Key features

• 24MP global shutter Stacked CMOS sensor
• High speed shooting up to 120 fps
• Pre-burst capture of up to 1 sec before the shutter is fully pressed
• Shutter speeds up to 1/80,000 with flash sync across the full range
• 9.44M dot (2048 x 1536px) OLED viewfinder with 0.9x magnification
• 2.0M dot rear LCD with tilting cradle on a fully articulated hinge

The a9 III will be available in early 2024 at a recommended price of $6000. This is a $1500 increase over the previous iteration from 2019. A matching VG-C5 battery grip that provides space for two batteries is available for an additional $398.

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Index:

What’s new

Global shutter sensor

The big news with the a9 III is the move to a sensor that offers a global electronic shutter: reading out all its pixels simultaneously so that there’s no lag or rolling shutter effect. Such sensors have existed before (some CCD chips, for instance), but this is the first one to use a full-frame sensor in a modern mirrorless camera to deliver the full potential benefits.

The sensor delivers the camera’s two main selling points: the global shutter, which extends what the camera can offer in three specific areas, and sheer speed. As well as having no motion distortion from its capture, the a9 III is able to shoot at up to 120 frames per second.

Its fast readout also allows incredibly high speed capture, with shutter speeds that extend to 1/80,000 sec. The global readout also means it can sync with flashes all the way up to its maximum shutter speed (though the power of the flash will be reduced at the very shortest exposures and may require the timing of the flash trigger signal to be fine-tuned so that the exposure syncs with the brightest point of the flash output).

There are downsides to the sensor, though: the global shutter design works by using what is effectively a second photodiode within each pixel to act as a buffer: holding the charge generated by the exposure so it can all be read out at the same time. This reduces the effective size of the photodiode used to capture the image, reducing the amount of charge each pixel can hold before it becomes full.

This reduced capacity for charge means the pixel becomes saturated sooner, so it can tolerate less light before clipping. In turn, this means it needs to be given less exposure, which is reflected in the base ISO of 250, 1.3EV higher than typical. Giving a sensor less light instantly reduces the image quality, because light itself is noisy, and this noise is more visible, the less light you capture.

120fps shooting

The new C5 button on the front of the camera is set, by default, to activate the speed boost function for temporary access to 120 fps shooting.

The super-fast sensor readout allows the a9 III to deliver a faster shooting rate than we’ve ever seen from a sensor this large. Whereas the previous generation of Stacked CMOS sensors with progressive readout would shoot at up to 30 frames per second, the a9 III quadruples this to 120. Sony has published a list of its lenses that can operate at this full speed.

It’s a reasonable question to consider how often even the most demanding sports photographers will need to shoot at 120 frames per second, and how much more sorting and selecting work will be created by generating so many additional files.

You can lower the burst rate to whatever makes the most sense for your specific subject, but there’s also an option to temporarily jump back to a faster rate when you hold a button down, meaning you could shoot at, say, 30 fps in the buildup to what you expect to be the critical moment, then press a custom button to give a faster, more concentrated burst around the moment of interest itself.

Like the other recent high-end Sonys, the a9 III has a pair of CFexpress Type A and UHS-II SD card slots set one within the other, providing compatibility with both the widely available SD format or the faster CFexpress format. Both are still significantly slower than the CFe Type B cards adopted by most other manufacturers.

Interestingly, the a9 III continues to use Sony’s preferred CFexpress Type A cards, which have half the read/write channels of the larger Type B format. This means the a9 III has to depend that bit more heavily on its internal buffer. It has the capacity to shoot 196 uncompressed 14-bit Raw files in a burst, allowing 1.6 seconds of capture at its fastest rate. This is nearly 10GB of data, which gives some idea of the size of the camera’s buffer but also of how quickly you’d fill up your cards if you shot at full tilt in Raw.

Pre-capture

The a9 III becomes the first Sony to have a pre-capture feature: starting to buffer images when you half-press the shutter button or hold the AF-On button, then retaining up to one second’s worth of images when you fully press the shutter. You can reduce the time period to as little as 1/200 sec if you’re really confident in your ability to anticipate the crucial moment, but the pre-buffer time isn’t affected by your choice of shooting rate.

Dedicated ‘AI’ processor

The a9 III gains the ‘AI’ processor that Sony first introduced in the a7R V. This does not add any ‘intelligence’ or learning in and of itself, but is designed to process the complex subject algorithms created by machine learning for functions such as subject recognition. This should boost the camera’s subject recognition performance compared to previous generations of cameras, such as the a1, making the tracking more responsive and more robust.

8EV image stabilization

The a9 III gets the flexible tilt-and-hinge cradle we previously saw on the a7R V. It can be manipulated into all sorts of positions, for wherever you’re shooting from.

The a9 III also gains the latest image stabilization processing algorithms, helping it deliver performance that’s rated at up to 8.0EV of correction, using the CIPA standard methodology. This is an appreciable increase over the 5.5EV offered by previous generations of cameras. Unlike Canon’s system, this doesn’t depend on synchronized use of in-body and in-lens IS mechanisms, so users should see an increase in correction performance over a wide range of lenses, though the peak correction may not be so well maintained quite so well at extremely long and short focal lengths.

C2PA authentication

Although not present at launch, Sony says it plans to add C2PA authentication to the a9 III. This is a cryptographic metadata standard developed by a range of software makers, camera makers and large media organizations that will provide a secure record of the file’s provenance and edit history, allowing media organizations to know that the images they are receiving can be traced back to a specific camera and haven’t been inappropriately manipulated.

How it compares

With its high shooting speed and pro-friendly features, the a9 III’s closest competitors are the pro sports bodies from Canon and Nikon, as well as Sony’s own a1. This is an exclusive group, not only in the sense of commanding a significant price but also in that they have professional support networks established to ensure working pros have the most possible ‘up’ time. While other cameras promise fast shooting and capable autofocus, these are the models that the most demanding professionals rely on.

The a9 III stands out, even from the other manufacturer’s pro-grade cameras, in offering 120 fps shooting as a standard mode, with full AF and Raw capture, whereas Canon’s R3 locks AF and AE at the first exposure (rarely ideal for the kinds of action shooting that require high speed bursts) and the Nikon outputs significantly reduced resolution JPEGs.

Like the EOS R3, the a9 III opts for speed over resolution, meaning it can’t deliver the 8K footage that the a1 and Z9 can. Also, any users hoping for Raw video will need to buy an external recorder, rather than being able to capture this in-camera, as you can on the Canon and Nikon.

The biggest apparent shortcoming is the relatively low battery life of the a9 III, as it’s a single grip camera and hence lacks the space for the larger batteries included in the Canon and Nikon. Adding the BG-C5 battery grip adds space for a second battery, as well as providing duplicate portrait orientation controls.

Body and handling

Although the company’s a7, a9 and a1 models all look similar, each generation has seen the control layout reworked and details such as the handgrip tweaked. The a9 III sees a larger than typical re-working of Sony’s ergonomics.

The grip is a little deeper, with a more prominent dent for the middle finger to rest in, but more significantly, the shutter button is placed on a surface that angles forward rather than sitting in the same plane as the camera’s top plate. This means you don’t have to rotate your hand or stretch your finger quite so far to reach the shutter. In turn, the custom buttons on the camera’s top plate have been extended upwards so that they’re still accessible from this less stretched position.

It’s a relatively small adjustment but enough that you’ll notice it after several hours of shooting. Given the a9 III’s target audience, it’s hard not to make assumptions that this change has been made in response to Sony’s tie-up with the Associated Press, giving the company more feedback from a large pool of working pros.

Beyond this, the body is pretty familiar from the previous generation of cameras, with most of the control points and custom buttons existing in the same places. The main exception to this is that the a9 III gains a fifth custom button, on its front panel. By default, this is used for the ‘speed boost’ function, but this can be modified.

The a9 III has the same 9.44M dot (2048 x 1536px) OLED viewfinder that first appeared in the Sony a7R V. The optics in front of the panel give an impressive 0.9x magnification, meaning it’s very large to look at, and the fast sensor means its full resolution is used even when refreshing at 120fps. There’s a 240fps mode if you need an even more frequent update of what’s going on in the scene, but this runs at a reduced resolution. The viewfinder shows no blackout at all when shooting images.

The rear screen is a 2M dot panel that’s arranged on a tilting cradle that is itself hinged at the side, providing a wide range of movement and adjustment.

The a9 III uses the same NP-FZ100 battery as all the most recent full-frame cameras have. It’s a well-sized 16.4Wh unit that powers the camera to a rating of 530 shots per charge, using the rear LCD according to CIPA standard tests. This drops to 400 shots per charge if you use the viewfinder. These are strong numbers compared to most cameras but some way behind those of its pro sports peers, which typically have a twin-grip body with space for a much larger battery.

Battery life can be increased significantly through the addition of the optional VG-C5 vertical grip. This adds the space for a second FZ100 and more than doubles the battery life, as Sony has developed a system for treating the two batteries as a single large power source.

It’s also worth noting that the CIPA standard tests are even less reflective of the behavior of pro sports cameras than they are elsewhere. Bursts of images use much less power than the individual shot shoot-and-review process that standard testing assumes. As such, a rating of 400 shots per charge for a camera that shoots at 120 frames per second should not be taken to mean that the battery will only last for 3.3 seconds of holding the shutter down. This is nowhere close to being true.

Image quality

Our test scene is designed to simulate a variety of textures, colors and detail types you’ll encounter in the real world. It also has two illumination modes to see the effect of different lighting conditions.

We’ve looked at the a9 III’s image quality and have found that its performance is up to a stop behind those of contemporary full-frame cameras. Essentially the halving of the photodiode size halves the amount of light the sensor can tolerate. This raises the base ISO, limiting the maximum image quality the camera can deliver (ie: comparing base ISO to base ISO).

The added complexity of the sensor’s design also means that it isn’t able to offer a second low-noise readout path as has become common in dual conversion gain sensors that dominate the market. This sees up to a stop noise penalty, relative to its full-frame peers.

All of that said, a lot of sports shooting doesn’t necessarily happen at ISO 100, so being limited to ISO 250 or higher needn’t be a major issue. Likewise, even a one-stop increase in noise at high ISO isn’t likely to be a deal-breaking difference, especially if the a9 III’s global shutter and incredibly rapid burst rates mean that it can get a shot that its rivals simply miss.

So, while the a9 III’s sensor tech may not make as much sense in other cameras, for the high-speed users it’s designed for, these aren’t necessarily a significant drawback.

Initial impressions

Only time in the hands of a large number of pro photographers will test how much value 120 fps capture with no risk of banding is, but historically faster has proven to be better, even when the current level of performance has let people get results.

We now have a full production spec a9 III but want to put it through its paces at some sporting events before drawing any firm conclusions about its overall performance, so these comments should still considered be initial impressions.

The arrival of global shutter is a significant advance for the industry, and provides a recognizable benefit in specific circumstances, specifically: high-speed flash sync, avoidance of banding with high-frequency displays and zero rolling shutter distortion for movies and very fast movement. However this capability comes at a cost, with the a9 III not being able to match the best image quality of its rivals.

The question is: do the camera’s strengths outweigh this cost for the types of shooting it’s designed for? The a9 III is a specialized camera designed for very specific types of shooting, not an all-rounder that might be used for landscape work, just as often as wildlife and sports. As a sports camera, speed is of the essence, and working at elevated ISOs is the norm. Likewise, the need for very broad dynamic range to be exploited during Raw processing isn’t likely to be a priority for many of its users.

The provision of a LAN socket and full-sized HDMI port show that Sony wants the camera to fit readily into professional workflows, and the camera will ultimately succeed or fail on that basis.

This isn’t to make excuses, just to put it in context. The a9 III offers capabilities for high speed capture far beyond those of its rivals, but at the cost of being a less flexible camera. Which may prove to be an acceptable, or even entirely reasonable, trade-off for sports pros, if it transpires that the ability to shoot at 120 fps around the critical moment, or to avoid any distracting ad-board flicker prove suitably valuable.

These caveats mean that the a9 III’s advances need to be seen in context: global shutter probably shouldn’t be assumed to be the future toward which all cameras are heading. For now the trade-offs mean it only makes sense for some photographers: those for which it’s designed. And those trade-offs would have more significant impact in smaller sensors, so we’re not suddenly dreaming of APS-C or Four Thirds sensors that utilize this particular technology.

Judged for what it is, though, the a9 III looks to be a very powerful addition to the market, with a lot of handling and workflow changes that will make it ideal for pro sports use. This is what we’ll be testing over the coming weeks. However, that doesn’t make it the camera by which all others should be judged.

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Pre-production sample gallery

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