The Sony A7C Underwater: Shooting Full Frame in a Half Size Housing

The Sony Alpha a7C Underwater: Shooting Full Frame in a Half Size Housing

How the heck did they do that and how does work?

Anyone keeping an occasional eye on digital camera progress knows that Sony has been on a tear for the last year or two. New cameras keep coming fast and furious. While the new top-of-the-line Sony a1 and the low light video king; a7SIII, have grabbed most of the headlines, the equally new a7C is almost as ground breaking in a different fashion.

The a7C is not the best Sony offers in any particular department. At 24MP, it has plenty of resolution for most of us, but is not in the same League as the a7RIV or the a1. It is also not Sony's fastest camera, but at 10fps, it is more than enough for most of as well. Video spec is good, but not in the same league as the a7SIII. So what does it provide? The Sony a7C offers very good all around performance in just about every category and does it in a surprisingly small package and at a very reasonable price. The camera is barely bigger than Sony's excellent a6600 APS-C sensor camera body which means the housings are barely bigger than the APS-C camera housings as well.

An equally exciting introduction for underwater shooters is the new Sony FE 28-60 f4-5.6 "kit lens" that is offered with the a7C. This super compact "walk around" full frame lens just happens to be a perfect companion to using a number of Nauticam's superb water-contact optics which we will get further into in a bit.

The Specs

  • 24MP BSI CMOS full-frame sensor
  • Bionz X processor (same as in the a7III)
  • 'Real-time tracking' AF system with human head, face, eye, and animal recognition
  • Oversampled 4K video at up to 30p, including 8-bit S-Log and HLG
  • Continuous bursts at up to 10 fps
  • Fully articulating 921k-dot touchscreen
  • 2.36M-dot EVF with 0.59x mag.
  • Mic and headphone sockets
  • Dual-band, 2.4 and 5Ghz Wi-Fi
  • Large 'Z-type' battery, rated to 740 shots per charge (Awesome!)

Housing Options 

The main reason to buy an a7C is because you want a high quality compact set up. A lot of people assume that as soon as you switch to a mirrorless format, that your underwater housing will get much smaller. But anyone who has looked at Nikon or Canon's excellent full frame mirrorless cameras, has had to realize that the underwater housings are close to the same size as a DSLR housing. Not so with Sony's a7C. Sony wanted to keep it small, and in the case of the Nauticam housing, they also have strived to make the desire to "go small" a reality. The NA-A7C housing is almost shockingly petite at fist glance. One's brain says "there can't be a full frame Sony in there". But in fact it is and all the controls are accessible.

Other housings will surly be coming and we will have to see how those deal with this new compact entry.

There is no "free lunch", so what do you give up with the a7C?

The short answer is not much. When you get down to the nitty gritty, there are some concessions to size. The a7C has no front command dial, so that means both aperture and shutter speed are controlled with rear dials with the left thumb when holding the housing. Different than we may be used to, but it works. The electronic viewfinder is lower resolution than the newest Sonys like a7IV and a1, but in practice it seems to work great with an enhanced Nauticam viewfinder which is not always the case with the largest and highest resolution EVFs. Another minor adjustment might be the position of the playback button to the right of the LCD. Those used to Nauticam placing the Playback lever conveniently by the shooters left thumb will have to adjust to a bit of a thumb reach with the right hand. Again, it is just some practice to get it right. Once mastered, being able to review images on command through the EVF was very helpful.

Can you shoot a full frame like a compact and do everything on the same dive?

In this case; yes. Using Sony's new 28-60mm lens in a compact flat port allows fantastic use of Nauticam's legendary WWL-1B optic (now with built in float collar) that provides fantastic 130 degree coverage, full zoom through and focusing down to the glass for amazing close ups. See something tiny you want to shoot? Pop off the WWL-1 and add a CMC-1 macro converter wet lens for tack sharp macro. See something really small? Try stacking TWO CMCs. Wow, pretty crazy stuff, but all doable on a single dive. 

We test a lot of gear here at Reef Photo & Video, but I will admit to being a little incredulous when first hearing of all these possibilities with a Sony full frame so I couldn't wait to take it on a test run. A lot people looking at this camera possibility will be DSLR shooters wanting to go smaller and crop sensor mirrorless shooters wanting to go full frame without bulking up too much. Both types of shooters will have some adjustments to make and I wanted to see how easy a transition it would be.

A first hand experience

Other than checking some basic settings in the a7C menu, I had no experience with the a7C, the NA-A7C housing, or the new 28-60 lens at all. I was starting from scratch, so I wanted to see what kind of range of images I could shoot with zero familiarity on a single dive. I was also diving a new site with no guide or buddy helping - just me puttering around getting familiar with the camera. Here is what I found. 

 At 28mm, the WWL-1 delivers all the crispy 130 degree coverage I love, but have never been able to get with a full frame zoom

 I shot this at 28mm at f6.2 - more open then recommended so the close lower left corner is a little soft, but far better than any rectilinear lens behind a dome and a slight zoom in cleans that up.


Zooming through the WWL-1 works well and offers smaller group portrait capability.

Popping the WWL-1 off and just shooting the 28-60 as a portrait lens worked quite well. Approximately 35mm focal length.

Zooming to about 50mm without any wet lens offers a nice tight portrait option.

Being such a small rig allows access to tight spaces for spur-of-the-moment close focus wide angle like under this small piece of wreckage. Room for the strobes proved the bigger challenge than the housing.

Shooting macro with a Nauticam CMC-1 and the lens zoomed to 60mm proved surprisingly easy, even shooting AF. Here I was focused on keeping the edges of the Christmas tree worm near the border of the frame to see how details held up - they did really well!

Here was the real test. 60mm with two CMC-1 optics stacked atop each other. Pretty amazing detail right to the edges. Not as easy as a single, but good to know the potential is there.

I think most people will be really happy with what you can accomplish with the the 28-60mm and a single CMC-1 - perfect for a smaller frogfish like this. Check out the detail on the frogfish and the sponge on the edge of the frame in the same plane of focus. The CMC-1 with the 60 offers very reasonable working distance.

First Dive Thoughts

I was very impressed with the flexibility of this system and the quality of the results. Was it perfect? Not quite. Was I perfect? Definitely not. But I think it worked amazingly well all things considered. On my next dive, I would add more flotation and improve the location of my lens holders to make it easier to switch things out. I definitely need to practice my playback through the viewfinder technique as I didn't have my muscle memory tuned to the new playback button position yet (I had to keep looking to find it which meant pulling my eye from the viewfinder). I was really happy with the Nauticam Enhanced Viewfinder performance with this camera and would consider it a must for still shooters. I also experienced zero blackout effect when shooting with the EVF. I think the brightness of the EVF needs to be tweaked a bit as well, as my exposures weren't always as bright as they appeared in the water.

Would I recommend this set up for the Full Frame shooter wanting to "get small"? Absolutely - when it comes to those priorities, the a7C is the only game in town.