Sony has established itself as a leader in the mirrorless camera market.
That's been true for a long time now, and with new offerings like the Sony a7S II and the Sony a7RIII that have incredible specifications, making the decision of what Sony camera to buy can be difficult.
Both of these cameras are fantastic, but there are enough differences between them that could sway you in favor of one over the other.
In this Sony a7S II vs Sony a7R III side-by-side comparison, I break down the essential specs so you can decide which of these great cameras is best for you.
Sensor Specifications
While both the Sony a7S II and Sony a7R III utilize a full frame Exmor CMOS sensor, there are important differences in the technologies that each camera uses.
For starters, the a7S II features 12.2-megapixels of resolution while the a7R III has 42.4-megapixels.
What's more, the a7R III is , which means the sensor's photosites are closer to the surface of the sensor, allowing them to capture light more effectively.
On top of that, the a7R III lacks an anti-aliasing filter, which gives it better performance when it comes to image sharpness.
Autofocus System Performance
Another crucial difference between these cameras is their autofocus system features and performance.
The a7S II has a 169-point autofocus system with contrast-detect points. It offers -4EV at f/2, which gives it one more stop of sensitivity than the a7R III. That's handy for capturing low-light still images.
The a7R III has a hybrid autofocus system with 399 phase-detect points and 425 contrast-detect points, making it a much faster system than what's found on the a7S II.
That makes the a7R III a more suitable camera for action photography, like sports, while the a7S II might be a better choice for low-light photography.
Get an in-depth look at the a7R III's autofocus performance in the video above by Jared Polin.
ISO Sensitivity
You might be surprised to learn that the a7S II has a much wider ISO range than the more expensive a7R III.
That's because the a7S II was purpose-built for video shooting, and as a result, Sony incorporated a much wider ISO sensitivity range into that camera.
The a7S II has a native ISO range of 100-102400, with an extended range of 50-409600, making it a much more capable low-light camera than the a7R III, which has the same extended ISO range, but due to the greater number of megapixels, the a7R III's sensor produces much more noise.
For an in-depth discussion of the a7S II's low-light performance, check out the video above by Linus Tech Tips.
In-Body Camera Stabilization and Continuous Shooting Speeds
Both of these cameras have the advantageous feature of in-body stabilization.
But, again, the manner in which these systems work is slightly different.
The a7R III, for example, has five-axis stabilization that offers up to 5.5 stops while the a7S II offers "just" 4.5 stops.
Likewise, these cameras offer different continuous shooting speeds.
The a7S II offers a maximum of 5fps shooting, which isn't all that great in today's market. The a7R III, though, has 10fps capabilities, which makes it a great option for sports or wildlife photography.
What's more, the a7R III has a buffer that can handle 76 JPGs or 28 uncompressed RAW files.
Editor's Tip: Ready to upgrade your camera but don't have a huge budget to do it? See how far you can stretch your dollar for a new camera.
Electronic Viewfinder and Rear LCD
Both of these cameras sport excellent EVFs and LCDs.
The a7S II has a 2.36-million dot EVF while the a7R III has the same 3.69-million dot EVF that's found in Sony's flagship a9 model.
Both EVFs offer 0.78x magnification, a maximum refresh rate of 100fps/120fps, and a 23mm eyepoint.
The LCDs on these cameras are the same size at three inches wide and they both tilt, but the a7R III's display is also touch-enabled while featuring higher resolution (1.44-million dots) than the a7S II (1.228-million dots) as well.
Video Capabilities
Both the a7S II and the a7R III have 4K video capabilities at 30p and can record video at their full pixel readout. That means that all the pixels in the camera's sensors are used for video, and then downsampled to 4K resolution.
That, in turn, means that both cameras produce exceptionally detailed video with no moire or aliasing.
Both cameras offer two video shooting modes as well - full frame mode in which the entire sensor is used and Super35/APS-C mode, in which the video is cropped by about 1.5x.
The Super35 mode is advantageous because it gives you better quality, particularly when shooting at high ISO values.
However, as noted earlier, due to it's less resolute sensor and incredible ISO Range, the a7S II is considered by many to be the better of the two cameras for shooting video.
Final Thoughts
As we've worked through the side-by-side comparisons of these cameras, one thing is clear - regardless of which of these cameras you buy, you're getting a rig that's highly capable and feature-rich.
What it will likely come down to is whether you need a camera primarily for photos or videos - the a7R III is better for photos (especially action photography) while the a7S II is better for videography, especially in low light.
Price is surely a factor as well.
The Sony a7S II runs about $2,400 for the body only while the Sony a7R III will set you back a shade under $3,000.
Are both cameras a big investment? You bet. But are they both rockstar rigs that any photographer would love? Absolutely!