Sony a7S III vs FX3: Which Compact Cinema Option is Best for You?

After a lengthy wait, Sony unveiled the a7S III, satiating years of desire for an upgraded king of mirrorless video. The release itself wasn’t so much of a shocker, even if the specs were top notch—perhaps even beyond expectations. However, the surprise came when just a short time after, Sony lifted the curtain on the FX3 as part of the Cinema Line. Borrowing bits from both the a7 series and the more traditional cinema cameras, the FX3 led many to ask the question: Should I get the a7S III or the FX3? 

Today we hope to guide you through the selection process and help you make the best decision for your requirements. We will be making the assumption that if you are comparing these two models you are likely focused on video performance. 

Table of Contents

• Image Quality 
• Physical Design 
• Audio 
• Operation 

Image Quality: Top-Notch Specs for Both 

Before we even get into which camera you should pick, we should start with why you should get either. The answer is image quality. 

The a7S III and FX3 share many specs and features: 

• 12MP Full-Frame BSI CMOS Sensor 

• Internal UHD 4K up to 120p in 10-bit 4:2:2 

• XAVC S-I and XAVC HS compression options 

• Raw 16-bit Video Output via Full-Size HDMI 

• Raw Video Recorded at 4.2K 60p using Atomos Ninja V/V+ 

• Internal Full HD up to 240p 

• Advanced phase-detect autofocus system 

• 15 Stops Dynamic Range 

• ISO Range 80-102,400 

• S-Log3, S-Cinetone, and Other Picture Profiles 

If you haven’t seen the cameras, and had to choose solely on the spec sheet, you would likely be wondering if they were the same camera. That sensor does a lot of heavy lifting. When you look at the two cameras, you will clearly see that the difference comes in the ergonomics and design. 

Physical Design: Very Different Mindsets 

Just look at these two cameras. Obviously, there are some huge differences when it comes to physical design. A fun note is that the cameras have different finishes. The a7S III is a classic black mirrorless camera, while the FX3 takes on the dark gray persona of the Cinema Line. A very small thing, I know, but it does clearly show the target audience for each camera. 

More similarities between these two cameras are manifested in them having the same ports. Even the locations of these are quite similar. They each have the following: 

• Full-size HDMI 

• USB-C 

• Micro-USB/Multi-Terminal 

• Multi-Interface Shoe 

• 3.5mm headphone jack 

• 3.5mm microphone input 

On the opposite side of the camera, you will find the card slots. Both have dual CFexpress Type A/SD slots. It’s a unique feature by Sony on its newest cameras―and is super nice.

WINNER: FX3

If you are planning on shooting mostly video, the FX3 offers so many advantages thanks to an optimized design. The only con, however, is huge: the lack of a built-in viewfinder. The a7S III is nice if you plan on switching back and forth between shooting both stills and video and working handheld with the EVF, but that’s about it. 

Audio 

Jumping off one of the key differentiators of the FX3—the removable top handle with XLR inputs—we are going to talk about audio.  

Out of the box, the FX3 is the clear winner since it comes with a top handle with two XLR inputs. That’s huge for on-the-go video production, although this can be added to the a7S III with the addition of the XLR-K3M XLR Adapter. Technically, audio quality here will be the same; however, the ergonomics of the FX3’s top handle put it over the top. Most a7S III users will want to build a rig or cage to handle the system better when the XLR adapter is mounted in the hot shoe.  

We don’t normally consider price here but, in this case, I find it relevant. Buying an a7S III with the XLR adapter will cost a couple of hundred dollars more than an FX3, which comes with the XLR unit. If your default is to pick up the XLR adapter for the a7S III, it might make more sense to just go with the FX3 instead. 

Otherwise, both cameras have the usual 3.5mm headphone and microphone inputs. Both are capable of recording quality inside. 

WINNER: FX3 

Operation 

This is where the decision gets tough and is likely the part where most people will need to look at their own preferred style. Among the biggest factors is the built-in EVF on the a7S III, which was removed to create the FX3. This makes the a7S III better for stills because the eye-level operation is a familiar form factor. The a7S III also looks like a mirrorless stills camera, meaning it can be a little more discreet for handheld operation. The EVF allows for better monitoring during bright days and provides an incredibly sharp, contrasty image. If you need an EVF, then the a7S III is a clear winner. 

Another interesting note is that the a7S III is completely sealed, since it does not feature a fan. This could mean in the worst weather conditions, the a7S III potentially might fare better. 

Where the FX3 excels is in the button layout and customization. The camera is designed for video first, and it gains things like a zoom rocker on the shutter release/record button for ergonomic control when working handheld. The top handle and 1/4"-20 threads are very much a video form factor and make a lot of sense for working handheld with accessories. The a7S III can get there, but requires a cage, which will add some weight. 

The way you plan to use your camera really depends on personal preference. 

WINNER: Draw 

Photo 

We’re keeping this one short since both cameras offer the same photo capabilities. The a7S III is the easy choice because its layout is better suited to stills operation while still being customizable for video. The EVF and general design make it much more sensible for capturing stills. 

WINNER: a7S III 

Final Thoughts 

Both cameras will serve you well. Pure quality out of these cameras is exactly the same in every way―you will be making your decision based on ergonomics and features. Anyone switching between stills and video should go with the a7S III. It also might make sense if you already are accustomed to the a7 form factor and are comfortable with it. For people who are buying a camera specifically to shoot video, you will be much better served by the FX3. 

If you still have questions or need some help, please feel free to reach out to our sales team or leave a Comment, below.