The Sony FX3 Underwater Review

The Sony FX3 has the Same Amazing Underwater Video Capability as the Sony A7S III in an FX Cinema-Line Body
By Nirupam Nigam

The Sony A7S III was a bombshell camera release for many underwater video shooters. It's been our favorite camera in 2021 for underwater 4K video with a wide range of options for video workflows and post-processing. The Sony A7S III is a particularly capable camera in low light environments, easily capturing clean video at ISOs past 12,800.This makes it perfect for many underwater shooting situations. Shortly following the rollout of the A7S III, Sony announced the Sony FX3 - which is basically the Sony A7S III in a Sony cinema line body. So why did Sony release the same internals in a different body and what does this mean for underwater video shooters?

We decided to keep this review of the Sony FX3 short and not dive with the camera, because everything you need to know about the camera can be read in our Sony A7S III review here. That being said, we do have new information on the A7S III for underwater shooters that explains why the FX3 might be a better option for underwater video shooters. Read below to find out why...

Sony FX3 Status: Available Now At Bluewater Photo

U.S. MSRP: $3899



Underwater housings for the Sony FX3 are available at Bluewater Photo!

Sony FX3 Camera Body

Nauticam Sony FX3 Underwater Housing

Marelux Sony FX3 Underwater Housing




Sony FX3 vs Sony A7S III

When we say the Sony FX3 is exactly the same as the Sony A7S III internally, we mean it. They share essentially the same specs, video quality, recording options, etc. However, there have been some changes to the body of the FX3 that orient it for cinema shooters:

  • The Sony FX3 is slightly smaller than the Sony A7S III and lacks a viewfinder
  • The FX3 is sold with a detachable handle. The handle has twin XLR/TRS terminals. These are audio features, and obviously the handle won't be of much help underwater.
  • The FX3 has a zoom lever, but there are only two Sony lenses that will work with this lever - the FE PZ 28-135mm f.4 and the FE C 16-35mm T/3.1. The latter may be useful for underwater video but not the former. 
  • There are multiple tally lights that have been added to the body, so you never have to worry about knowing if the camera is recording. 
  • The Sony FX3 has a cooling fan which will extend recording times. However, overheating is not a huge issue with the Sony A7S III. However, we have had reports that at 4K/120p continuously filmed underwater for 20 minutes, the camera can over heat. So if you want to do a lot of slow motion filming, the FX3 might be a good option.
  • The FX3 body has thread holes for accessories
  • Price: The Sony FX3 clocks in at $3899 whereas the Sony A7S III is $3499. This is likely because of the included handle/XLR adapter


Should You Buy the Sony FX3 or the Sony A7S III?

Underwater, many of the differences between the Sony FX3 and the Sony A7S III become a moot point. The handle and XLR adapter and thread holes will not be useful to underwater shooters. It's specifically the handle that comes with the FX3 that contributes to the increase in price. When considering the Sony FX3 vs the Sony A7S III there are two main reasons why the FX3 could be a better choice for a dedicated video shooter:

  1. The Nauticam housing for the Sony FX3 is actually slightly smaller than the the Nauticam A7S III housing (1.97kg for the FX3 housing vs 2.7 kg for the A7S III houing). Because there is no viewfinder on the FX3, it is not possible to use a magnified viewfinder with this housing for composing. Currently there is only one other model available for the FX3, the Marelux Sony FX3 underwater housing.
  2. The Sony A7S III has been reported to overheat when shooting 4K/120p for extended periods underwater (20 minutes or greater). Although most people don't shoot at 120fps for long periods of time, there are some underwater situations where this could be useful if you have the storage capacity. So the addition of the cooling fan could be very useful.


Sony FX3 Underwater Housings

nauticam sony fx3 underwater housing

Nauticam Sony FX3 Underwater Housing

There are currently only two underwater housings available on the market for the Sony FX3 - one of which is the Nauticam FX3 housing. At 1.97 kg it's actually .73 kg lighter than the Nauticam Sony A7S III housing, making it a good option for any video shooter looking to reduce weight. The housing is machined from solid anodized aluminum and includes many of the great features native to nauticam - like their port locking system and compatibility with nauticam optics. The housing is compatible with external monitors for HDMI 1.4 and 2.0 cables and comes with a leak detection system.


Marelux Sony FX3 Underwater Housing

Marelux Sony FX3 Underwater Housing

The Marelux Sony FX3 housing is the newest underwater housing available for the FX3. It's built from high-grade aluminum alloy, which means it can handle being used in harsh conditions. It has great ergonomics and all camera controls are in easy to use places. All in all, the Marelux underwater housing for the Sony FX3 is an excellent choice for photographers looking to take the FX3 out with them on their next dive adventure. 



Underwater housings for the Sony FX3 are available at Bluewater Photo!

Sony FX3 Camera Body

Nautiam Sony FX3 Underwater Housing

Marelux Sony FX3 Underwater Housing

There are many more housing options for the Sony A7S III at Bluewater Photo:

Nauticam Sony A7S III Underwater Housing

Ikelite Sony A7S III Underwater Housing

Sea & Sea Sony A7S III Underwater Housing

Aquatica Sony A7S III Underwater Housing

Isotta Sony A7S III Underwater Housing


Order a Sony A7S III Camera Body at Bluewater Photo:

Sony A7S III Camera Body

Read Our Top Sony A7S III Underwater Settings

Check out our full Sony A7S III Underwater Housing Buyer's Guide


Contact Us for a Special Sony A7S III Underwater Package





Nirupam Nigam is the Editor-in-Chief of the Underwater Photography Guide and the President of Bluewater Photo - the world's top underwater photo & video retailer. While growing up in Los Angeles he fell in love with the ocean and pursued underwater photography in the local Channel Islands. After receiving degrees in Aquatic and Fisheries Science and General Biology, as well as a minor in Arctic Studies, Nirupam worked as a fisheries observer on vessels in the Bering Sea and North Pacific. Since then, Nirupam has been a full time underwater photographer and photo gear head. Check out more of his photography at!


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