Fiji with the NA-A7SIII and NA-NinjaV
The A7S III is one of the most anticipated model updates in the full-frame mirrorless space, building on the low-light powerhouse A7S II. The A7S models, as opposed to their high-resolution 'R' counterparts, feature relatively low megapixel count but pack amazing ISO flexibility and strong video specs due to their low pixel density. When filming underwater, especially in environments with little to no natural light or when using color-correction filters, the ability to sacrifice ISO for aperture or shutter speed with little penalty is critical. While the A7S II excels in this arena, its ability to capture an accurate custom white balance underwater was lacking and required using color-correction filters in many situations or relying solely on artificial light.
While the A7S III features impressive internal recording options and excellent LCD/EVF screens, pairing it with an external monitor or monitor/recorder offers easier visualization of composition and exposure or even expanded recording options. In this case, we used the Atomos Ninja V recording monitor in the Nauticam NA-NinjaV housing, connected via HDMI.
Continuous autofocus has always presented a challenge for underwater wide-angle video. More often than not, the camera would shift focus to a distracting foreground intruder such as wrasse or other curious fish in the middle of a sequence thereby ruining the shot. With all the improvements to the autofocus system of Sony full-frame mirrorless cameras I decided to give it another try and was pleasantly surprised. The system chose focus well and maintained it, even in the challenging anthias-filled reefs of Fiji.
To enable switching between continuous autofocus and manual focus easy, reassign the 'AF-ON' button to toggle between AF/MF which gives a hybrid back-button autofocus that didn't require holding the button down to use the autofocus for the entire shot. Toggling it on momentarily gives a similar result to the standard back-button momentary autofocus. Fort many scenes with dynamic action, where the subject to camera distance can change dramatically, a reliable continuous autofocus system can help insure sharp footage throughout a shot.
The A7S III's HDMI output signal can be recorded as ProRes RAW with the Atomos NinjaV/V+ recording monitor in addition to other ProRes or more compressed formats. It's important to note that the RAW output option must be set in camera and cannot be changed while underwater as it requires an on-screen 'touch' confirmation on the NinjaV when changing to or from RAW recording. When shooting in RAW, the camera defaults to the minimum base ISO of 640 and the 'PP10" picture profile which is the 'SLog3/SLog3-Cine' gamma and color profile. It's important to choose the correct monitoring profile in the NinjaV to correctly visualize the image on the screen.
With the Ninja's monitoring function its possible to either upload a commercially available LUT or to choose one of the available standard HDR or Rec709 profiles. Using this monitoring function allows you see an approximation of the final image and judge exposure correctly. Other tools such as the waveform monitor are crucial for preventing over or underexposure. While the ProRes RAW is a very easy to use and pliable format, the size of the files makes it impractical for every shot. When shooting in challenging lighting conditions or when above average amounts of color correction are anticipated, RAW is probably the best option. In most typical shooting situations, ProRes HQ or the camera's internal compression H.264/265 is more than suitable. Simultaneous recording to the camera's memory card and the NinjaV is possible as well and makes for a good backup solution.
It's important to also note that recording in ProRes RAW, especially at 60p, generates significant heat and using the Turbo fan mode becomes necessary. This will, however, reduce operating time on the monitor/recorder due to increased battery usage. If the monitor becomes too hot, it will dim the screen and give a visual warning which can interfere with composition.
The A7S III does a great job of capturing a custom 'one-touch' white balance underwater, significantly better than the A7S II. While it does actually require three button presses, it is still very simple and does not require taking a reference photo beforehand. Assigning the WB function to a custom button (the 'AEL' is most conveniently positioned) allows for quick access. Once this button is pressed, selecting the 'set' button once the camera is pointed at the target is all that is required. There are three custom white balance preset slots available.
Note: When using Ambient Filters on LED lights such as the Keldan AB6/12, best results seem to come from turning the lights off before taking a white balance as they function more as fill lights, not the primary light source in this configuration.
Nauticam Water Contact Optics
The NA-A7SIII uses the N100 port system and has access to the wide range of corrective underwater optics. For this trip, most footage was captured using the compact Sony FE 28-60mm F4-5.6 lens which can be paired with either the travel-friendly and bayonet mountable WWL-1B or the larger WACP-1. Both provide an ultra-wide 130º field-of-view, full zoom-through, excellent corner sharpness at even wider-open apertures like F5.6, and a near 0" minimum focus distance. In addition to these important metrics, the resulting image from these lenses is the natural look of the resulting image without the extreme barrel or pincushion distortion found in conventional fisheye and rectilinear configurations. An added benefit of the WWL-1B system, in addition to its more compact design, is the ability to remove it underwater and mount either the CMC-1 or CMC-2 macro optics to shoot both standard and super macro in addition to wide-angle all on the same dive.
New Enhanced Viewfinder
The A7S III features a larger Electronic Viewfinder (EVF) which benefits from Nauticam's newest Enhanced Magnifying Viewfinders (0.8:1). For those not looking to use an external monitor or even the camera's LCD screen, the 45º or straight viewfinders allow for edge-to-edge viewing of the viewfinder at a comfortable viewing angle. The camera's stabilization and high frame rate options help reduce unwanted image movement when using this more streamlined setup.
This video was produced from a mix of footage recorded in 60p on the Atomos NinjaV in ProRes RAW, ProRes HQ as well as H.265 10-bit 4:2:2 600M recorded internally to a CFexpress card in the A7S III.