The Sony a7R III is a full frame mirrorless camera that shoots 42 MP stills, 4K video, and has a great low light capability. The Sony a7R III has what is called a back-illuminated sensor. By moving electronics off the sensor, the sensor can gather more light, leading to better low light and high ISO performance. A full discussion of this technology is beyond the scope of this article, but in viewing images shot from 100-1600 ISO, we can’t really tell much of a difference in noise. So we would say, yes they did accomplish low noise, high ISO, and hi-res in the same camera. The seemingly impossible has become possible! The result is among the best image quality you can get from a camera sensor on the market, second only to the Nikon D850 , but only by the absolute thinnest of margins. Sony,a7r,iii,3,mk,mark,alpha,underwater,camera,housing,review,Sony,alpha,α,a7R,a7riii,a7r3,a7rlll,m,mk,Mark,iii,3,lll,mk3,mklll,mkiii,markiii,mark3,Underwater,camera,housing,Review

Sony a7R III Underwater Camera Review

Hi-Res Photos, Low Light Performance

The Sony a7R III is a full frame mirrorless camera that shoots 42 MP stills, 4K video, and has a great low light capability. The Sony a7R III has what is called a back-illuminated sensor. By moving electronics off the sensor, the sensor can gather more light, leading to better low light and high ISO performance. A full discussion of this technology is beyond the scope of this article, but in viewing images shot from 100-1600 ISO, we can’t really tell much of a difference in noise. So we would say, yes they did accomplish low noise, high ISO, and hi-res in the same camera. The seemingly impossible has become possible! The result is among the best image quality you can get from a camera sensor on the market, second only to the Nikon D850 , but only by the absolute thinnest of margins.



Great Control Set for Underwater Shooters

The control set of the camera is very well laid out and ergonomic, making quick changes on the fly super easy and is a little bit of an upgrade over the Sony a7R II. There are dedicated dials for shutter speed, aperture, ISO, and exposure compensation. There’s a number of custom function buttons and most other buttons can have their functions reassigned. There’s the ability to reassign focus to the AF-ON button on the back of the camera which can be accessed by your right thumb, just like an SLR.



Massively Improved Autofocus

Autofocus on the previous model Sony a7R II tended to lack speed. It was the slowest focusing full frame camera at the time it was released from our experience underwater.





Sony a7R III with Canon 8-15mm Lens with Metabones Adapter | 1/100 sec | f/13 | ISO 400 | 15mm

Focus on close focus wide angle shots is critical where the depth of field is limited. The Sony a7R III autofocus updates quickly and accurately, even when choosing its own focusing point—and stays locked on the proper part of the frame.




That has completely changed with the Sony a7R III. It features a completely new AF system this is lightyears ahead of the previous model. The focus is now updated at a rate of 60 times per second and is extremely accurate and fast. While normal wide-angle shooting shouldn’t be a challenge to any pro-level camera body, close focus wide-angle, with subjects inches from the lens, can force the camera’s autofocus system to work harder to pick out proper autofocus points, and the Sony a7R III nails it.



The only downside in autofocus is in super macro. The focus tends to hunt and be slow, forcing us to switch over to manual focus for the smallest critters on the reef.



The biggest surprise was when using Canon lenses with a 3rd party Canon to Sony lens adapter. The focus was just as fast and accurate as a native Sony lens, whereas in the past the Sony a7R II was so slow as to barely be usable and the accuracy sometimes left images completely out of focus. With the latest Sony AF system and using Canon lenses with a 3rd party adapter, the lack of a proper native Sony fisheye lens is solved by using the Canon 8-15mm.





Sony a7R III with Canon 8-15mm Lens & Metabones Adapter | 1/160 sec | f/11 | ISO 200 | 8mm

With a 3rd party lens adapter, Canon lenses can be used with theSony a7R III. The Canon 8-15mm is our favorite choice for wide angle lens for the Sony a7R III, and with the new autofocus system from Sony, focuses just as fast and accurate as a native Sony lens.




Focus Peaking—See Super Macro Critical Focus Even If Your Vision Isn’t Perfect

When in MF mode you can also have focus peaking active. This will show you areas in focus highlighted in your choice of color. The color isn’t too overbearing and is a massive help in determining critical focus. For those who can see the critical focus on a screen or optical viewfinder very well, this is a must for macro shooting. Just look for when the critical area you want in focus is highlighted in the color of your choice, and fire.





Sony a7R III with Sony 90mm Lens | 1/160 sec | f/22 | ISO 160 | 90mm

Focus peaking with the Sony a7R III is an easy way to tell critical focus of macro subjects even if your eyesight isn’t 100% perfect.




Focus peaking also works with depth of field (DOF) preview. The gain on the screen compensates for any loss of light from stopping the lens down, but it is still important to use a focus light to help see subjects clear and help with AF performance in low light. This is an advantage over SLRs as most cameras either don’t have access to the DOF preview button, and when you do, the viewfinder is too overly dark to actually see anything when the lens is stopped down, plus there is no peaking in the viewfinder.



Underwater White Balance Performance—A Step in the Right Direction

In the past, Sony cameras were not able to execute a custom white balance even in the shallowest of depths. The color temperature would max out at 9900 Kelvin, and for underwater white balance, we need a limit somewhere in the upper reaches of 50,000 Kelvin plus. This limitation basically made underwater ambient light wide-angle video unusable, as this could not even be recovered in post very well. Now with the Sony a7R III when executing a manual white balance at depth, it now reads >9900 Kelvin, and it is actually making an adjustment above that level. Unfortunately, it’s still not perfect with the water's color turning magenta instead of blue. This can be fixed in post at least and is an improvement over previous models, but still lacks the proper color one needs for wide angle ambient light video.



Conclusion

If you are considering a camera in the range of a Sony a7R III, you may also want to look at SLRs such as the Nikon D850 or Canon 5D IV. If video is your thing, the Canon with its perfect manual white balance is the way to go. The ultimate wide-angle photo camera choice is the Nikon D850 with a tiny bit more of dynamic range and an optical viewfinder. Although the camera body is quite a bit smaller than its SLR brethren, by the time you add on a housing, and ports for full frame optics, it’s not really that much smaller, either in size or price. All that being said, the Sony a7R III is hands down the best mirrorless camera on the market for image quality and a toss-up in a contest for best image quality for a full frame camera versus the Nikon D850 . Don’t let its small size fool you—this is a pro-level camera.







Sony a7R III Pros



  • 42.4MP sensor produces the best still image we’ve ever seen from a mirrorless camera
  • Worry-free wide-angle autofocus performance - it’s fast and accurate
  • Full-sensor 4K video with the ability to crop
  • Canon lens compatibility with a lens adapter
  • Excellent low light ability
  • Excellent focus peaking for when your eyes can't see critical focus
Sony a7R III Cons



  • White balance is improved, but not great. However it is recoverable through post-processing
  • Electronic viewfinder makes foreground difficult to see when shooting wide-angle








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