Sony A7S III: Initial Thoughts & Review

The Sony A7S III is a "cool" camera that features 4K video at 120 frames per second with longer recording times than the Canon EOS R5
By Nirupam Nigam

After waiting for years for the release of the Sony A7S III, many Sony shooters were even starting to wonder if Sony had just decided to skip that camera model altogether. But all that waiting ended in July 2020, when Sony announced the A7S III - a camera with spectacular video capability that just might become the top camera for underwater video this year. The announcement came nipping at the heels of the Canon EOS R5, which had been marketed largely for its 8K RAW video specs. The A7S III can't capture 8K video, but it can certainly keep its cool and record longer than the EOS R5. So which full-frame mirrorless camera will be better for underwater video? It's hard to say. But what we do know is that the Sony A7S III can recording 4K @ 120fps with no recording time limits (though it may be limited by heat after an hour)! 


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Nauticam Sony A7S III Underwater Housing

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Sea & Sea Sony A7S III Underwater Housing

Aquatica Sony A7S III Underwater Housing


Isotta Sony A7S III Underwater Housing

Key Sony A7S III Specifications

  • 12 MP BSI CMOS Sensor
  • Bioz XR Image Processor
  • ISO 80-102,400
  • Dual Gain ISO capability
  • 4K video up to 120 fps
  • No recording time limits. Could be limited by heat (4K @ 60p for at least an hour)
  • 4K @ 60p 16-bit RAW video with external recorder
  • 10bit 4:2:2 internal recording
  • S-LOG and RAW (external) recording capability
  • 5 axis in-body image-stabilization (IBIS)
  • Dual card slots (either SD or CFexpress Type A)
  • 9.44 M dot EVF

Sony A7S III vs the Canon EOS R5

The Sony A7S III and the Canon EOS R5 don't really compare as far as cameras go, but both Sony and Canon positioned themselves for a comparison with their marketing. Canon began by introducing amazing video specs on the EOS R5, capable of 8K RAW internal recording @ 30 fps. The EOS R5 can also record 4K video up to 120fps. Due to the limited number of pixels on the sensor, the A7S III is only capable of shooting 4K video up to 120fps. That being said, 8K video is the only spec where Canon is superior. 

The A7S III is a camera that's designed for much more practical video useage for one reason - it doesn't overheat as quick as the EOS R5. The A7S III can shoot 4K @ 120 fps for at least an hour at room temperature whereas the EOS R5 can shoot at that frame rate for only 15 minutes. For most applications, the A7S III is going to be the better choice. Very few individuals have a need for 8K video and want to deal with the processing and data demands that come with it. For underwater videographers looking to shoot smooth 4K video at 60fps or 120fps, the Sony A7S III is going to be the camera of choice.

The A7S III also offers tantalizing video features like 16 bit recording at 4K @ 60fps with an external recorder and 15 stops of dynamic range with the SLog picture profile. When it comes down to it, if you're a serious video shooter, the A7S III is the camera of choice. HOWEVER, if you're looking for a camera that can also take amazing still photos, get the EOS R5.


Sony A7S III for Underwater Video

When it came to the A7S III, Sony didn't veer away from the goal. It's pretty clear that the A7S III will be the top full-frame mirrorless camera for underwater video in 2020. It beats out competitors like the Pansonic S-series with better lens options and the Canon EOS R5 with better engineering and recording times. The 12 megapixel BSI CMOS sensor makes it an extremely capable low light video camera with large pixels. The dual gain function provides dual native ISOs so that you can shoot in really low light with limited noise. When it comes to practical applications, dual gain ISO is going to be an essential feature for capturing video in overhead, nighttime, and low light environments. It will enable videographers to shoot in Log profiles without too much nose in their shot. We are really excited to put the second base ISO to the test in the dark waters of the Eastern Pacific. Macro videographers are bound to be excited for the ability to shoot 16 bit 4K video, albeit to an external recorder. It's going to be wonderful being able to capture the full spectrum of color that is displayed by some of the wild and wonderful critters found on reefs and in muck. For videographers try to shoot quick moving subjects in tumultuous water (e.g., surfers, sea lions, sharks, bait balls), Sony's IBIS and 120 frames per second @ 4K is going to provide mindblowing stability. Action shooters will be able to create slow motion clips in crisp resolutions. If you ever find yourself with a corrupt card, dual card slots will be a lifesaver. Finally, Sony's S-Log profiles and RAW recording capability mean that you can edit and color grade your video with the ultimate creative experience. What more could you want in an underwater video camera?


Best Underwater Lenses for the Sony A7S III

In recent years, Sony has gone from having a limited supply of lenses for underwater photography to one fo the best repetoire of native lenses for full-frame mirrorless cameras on the market. Sony A7S III users have an excellent set of choices for shooting macro, wide, mid-range, and fisheye. 


Wide-Angle Lenses

The Sony 16-35mm F4 lens is the top wide-angle lens choice for photo and video. If you’re looking for something even wider to get nice close-focus wide-angle (CFWA) shots of reefs there are a couple of options for shooting fish-eye. The 28mm prime lens with a fisheye conversion lens will give the widest possible angle of view. The fisheye conversion lenscan be used behind a large or small dome port, while the Sony 16-35 mm F4 les is recommended for use with an 8-inch dome or larger.

Wet wide-angle lenses are a great option with this camera. We recommend the Nauticam wet wide-angle lens or the Kraken KRL-01 wet wide-angle lens with the 28mm prime lens. All of these options are very sharp and will result in stunning wide-angle photos. 


Mid-Range Lenses

The Sony 24-70mm F 4 or the Sony 28-70mm F3.5-F5.6 are good choices along with the 35mm F2.8 portrait lens.


Macro Lenses

For underwater photography, the Sony 90mm macro prime lens is the best choice for small fish and macro subjects. It is exceptionally sharp and produces high quality images. A 50mm macro lens is another great option, though it doesn't focus as quick as the Sony 90mm.


Canon Lenses

Canon lenses can be attached to the Sony A7R IV with the Metabones, Sigma MC-11, or Photodiox adapters, but auto-focus is generally better with Sony lenses. Lenses like the Canon 8-15mm, 16-35mm, and 17-40mm work well. The Canon 8-15mm fisheye lens is recommended when shooting video using Super 35 crop mode. You can also use the Canon 100mm lenses.


Lenses for Underwater Video

When in Super 35 mode we recommend the Sony 16-35mm F4 lens or the Canon 8-15mm fisheye lens. For closer shots use the Sony 24-70mm or the 28-70mm zoom lens. 


Top Underwater Housings for the Sony A7S III

We anticipate underwater housings for the A7S III to be produced by all leading underwater housing manufactures. Isotta, Sea & Sea, Aquatica, and Nauticam will likely produce anodized aluminum housing options. An excellent polycarbonate option can be expected from Ikelite. Due to differences in camera design, we anticipate that the A7S III will require a different housing than the A7R III or A7S II. 




The Sony A7S III is our top full-frame mirrorless camera for underwater video in 2020. It features dual gain ISO capability, 4K video up to 120 fps with no recording limits, 16 bit recording up to 4K @ 60fps, S-Log profiles with 15 stops of dynamic range, dual card slots, IBIS, and an amazing 9.4 million dot EVF. For real world use, underwater videographers have just been given a new cutting edge tool to produce spectacular, smooth, colorful scenes for years to come.


Nirupam Nigam is a dedicated underwater photographer and fisheries scientist. While growing up in Los Angeles he fell in love with the ocean and pursued underwater photography in the local Channel Islands. He received degrees in Aquatic and Fisheries Science and General Biology, as well as a minor in Arctic Studies, at the University of Washington. Now he works as a fisheries observer on boats in the Bering Sea and North Pacific. When he is not at sea, he is traveling with his fiancee and taking photos. Check out more of his photography at!


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