Sony a9 III – the Best Alpha Camera for Video?

Camera News

by Omri Keren LapidotNovember 9^th, 2023

Sony’s brand new a9 III boasts an innovative global shutter full-frame sensor. This chip enables instantaneous read speed and extremely fast motion and stills shooting rates. Will this be enough to crown the a9 III as the best Alpha camera for video? On the other side of the ring, we have the impressive a1 with its high-res stacked CMOS in all its 8K glory. Also pitted here is the venerable a7S III, a fan-favorite workhorse and among the most efficient video tools around. Let’s dive into the match!

Tradition of innovation

Sony is well known for its technological ingenuity and prowess. The first manufacturer to launch a full-frame mirrorless camera (the α7 in 2013), the first to incorporate a stacked CMOS sensor into a hybrid camera (the a9 in 2017), a market leader in the field of autofocus, and, as of yesterday (Nov. 8th, 2023) – the first manufacturer to put a full-frame global shutter sensor in a mass-market camera – the Sony a9 III. The new camera is undoubtedly impressive, but to reign supreme, it has to pass over some serious hurdles among its stablemates.

Power trio – the a1, a7S III and the new a9 III

Sony’s lineup offers many excellent video cameras catering to various use cases. Here we’ll discuss the aforementioned trio, which, in my humble opinion, represents the pinnacle of the Alpha line regarding motion capture. They all have significant features that render them all adequate tools for video. Among those we find:

Similar features

• 4K recording up to 120p
• 10-bit 4:2:2 internal recording, up to 600Mbps
• 16-bit RAW video output via HDMI
• Full-size HDMI-A port, mic/headphones 3.5mm jacks, and smart hot shoe connectivity
• In-body image stabilizer and electronic stabilization options
• Dual CFExpress type A / SD UHS-II card slots

Unique traits

Each of the trio possesses some unique abilities. The Sony a1 has a massive resolution advantage. Its 50mp sensor enables 8K recording at normal speeds. The 4K can be subsampled from the entire width of the sensor, or oversampled from a Super35 5.8K area. This allows for some level of flexibility, but may also degrade the full-frame 4K sharpness.

The Sony a7S III is the most affordable camera. The use of a relatively low-res sensor may render it unusable for many stills applications, but we’re talking video here. Though limited to 4K recording without much oversampling, the enormous pixels on the 12mp sensor create a satisfying 4K image that won’t change much when upping the frame rate. Those large pixels are also responsible for the impressive high-ISO capabilities the a7S III is famous for.

The new Sony a9 III is the master of speed. Its impressive abilities all rise from its core feature – the global shutter-enabled 24.6MP full-frame sensor. Its instantaneous read speed enables 6K oversampled 4K video up to 60p resulting in sharp, clean images. It also goes the extra mile with its uncropped 4K/120p. The autofocus system is Sony’s most recent AI-based algorithm, but I suspect that the faster readout flow will make it even better (is that even possible at this stage?)

Three different sensor architectures

As mentioned – the a1 boasts a 50MP sensor. The more pixels a sensor has, the slower its readout will be (as long as we compare equivalent sensor generation and architecture). This constant poses a challenge to a camera that aspires to rule both stills and video. The solution is a technological one: a Stacked CMOS. This specific architecture, which debuted on the original a9, speeds up the read speed, enabling quite a decent 16.6ms in 8K. While solving this specific problem, the use of such tech did result in one of the most expensive hybrid cameras around.

The a7S III takes the opposite route regarding resolution with its 12MP sensor. Having fewer pixels may seem like a disadvantage at first, but it makes the camera much more affordable and theoretically less prone to overheating. The fewer pixels the camera has to sample the less processing power it requires. Additionally, a low-res sensor reads faster since it has fewer pixels to read. The a7S III achieves very good read speed with a BSI CMOS. It’s actually among the fastest in the industry, all while omitting the higher, more expensive technologies, and significantly reducing the camera’s cost.

The new a9 III takes it one step further with the use of the “holy grail” of fast sensors – a global shutter. As mentioned before – the global shutter reads each and every pixel all at once. This unique chip architecture completely eliminates any strobe synchronization effect, flash sync speed, or the infamous rolling shutter effect. Working at extreme 120fps speed, this loads the camera’s processor with a constant flow of information, optionally improving other data-related abilities such as tracking auto-focus and subject recognition (though we’ll have to wait for an actual test to see if theory translates to practice).

What is the deal with global shutter in real life?

Few cameras use global shutters, and the a9 III is the first stills-oriented camera to use one (excluding Hasselblad’s mechanical global shutter, but that’s another story for another time). Regarding how unique this sensor is among stills cameras, it’s no surprise that Sony emphasized still imagery over video at its launch event.

When it comes to motion capture, there’s one clear advantage: no matter how fast the camera or the subject moves – no distortion will take place. No matter how flickery your light source is – no banding will occur. Global shutter provides some extra peace of mind and lets you focus on the creation itself.

But is it that good?

Well, it is. It’s that good. The advantages are absolute. But are they really necessary? Well, that’s a bigger question. First, let’s talk about the prices of a global shutter. The most obvious is, well, the price. The a9 III will set you back $5999. This kind of money could buy you about two a7S III cameras, or maybe a nice lens, some accessories, etc.

Other potential prices are speculative at this stage, at least until we get a production camera and run it through our rigorous lab tests. One may be the dynamic range. Sometimes faster readout speeds come at the cost of dynamic range. Other times, the results aren’t as decisive (as seen here with the RED KOMODO 6K, another global shutter camera). Another issue that can occasionally affect hybrid cameras with high data rates is the well-known problem of overheating. The amount of data crunched by the a9 III is extraordinary, and it probably uses some sort of passive thermal management. We can’t yet do the math, but I won’t be surprised to see some limitations regarding its high-speed settings.

TL;DR, which is the best?

Well, as always – it depends. The new a9 III brings some impressive features and abilities to the table, but when looking closely, most are quite niche. If your project brief includes extreme action shooting, fast-moving subjects, and chaotic situations, the a9 III may be the best camera. The a1 will provide better all-around features, covering most normal use cases for either stills or video (and then some). The a7S III is such a popular camera for a reason. It caters to most video needs and does so with excellent efficiency.

So are you excited about the new a9 III? Will it turn your creative process upside down? Or maybe another a7S III is a better option because if it ain’t broke don’t fix it? Let us know in the comments.