Sony's recent full-frame mirrorless releases have all included improvements and new features that have everyone hoping to get one in the water. The A7 IV's position in the Sony full-frame mirrorless lineup is between the A7S III and the A7R IV. As the core-model, it has a well balanced mix of still and video features that make it excellent for those looking at a hybrid full-frame solution. The improved menu system, solid autofocus, excellent EVF and great image quality all make the A7 IV an outstanding underwater still and video camera. The Nauticam NA-A7IV builds on the long successful lineup of A7 series housings with intuitive control placement, innovative engineering and the largest selection of optics available.
These field notes focus exclusively on the still imaging capabilities of the camera. For this trip the NA-A7IV housing was paired with INON Z-330 strobes and both the WACP-1 and WWL-1B, both of which use the Sony FE 28-60mm F4-5.6 lens. For macro the Canon EF 100mm f/2.8 Macro IS USM lens with a Metabones Canon EF-mount to Sony E-mount adapter. As using both the WACP-1 and the Canon 100mm require the use of the Nauticam N100 to N120 35.5mm Port Adapter II, it was easy to switch between the setups, swapping only the WACP-1 for the N120 Macro Port.
Flamboyant cuttlefish F3.5, 1/200, ISO 100. Landing critical focus even at F3.5 was easy with the camera's EVF and the Nauticam Angled Full Frame Viewfinder 0.8:1.
Juvenile mimic octopus F5.6, 1/250s, ISO 50. Even with manual focus, focusing on the eye of this fast moving juvenile mimic octopus was easy.
Glossodoris acosti nudibranch f11, 1/200s, ISO 100. When using creative lighting, the image review in the EVF allows for on-the-fly strobe adjustments without removing your eye from the viewfinder.
Ghost pipefish pair F6.3, 1/125s, ISO 100. Shallow depth of field allows the subject to pop from the close background while still allowing that to be a beneficial aspect of the image.
When used with the Nauticam Enhanced Viewfinder 0.8:1 45º model, the A7 IV's electronic viewfinder makes nailing macro focus a snap. The majority of the sample images are shot at F6.3 or below for dramatic depth-of-field with moving subjects and manual focus. The detail, sharpness and refresh rate of the viewfinder were excellent. As with all mirrorless cameras, having instant review of the image in the viewfinder allows for strobe or setting adjustments without removing your eye from the viewfinder, eliminating the need to reacquire your subject.
Juvenile Lionfish F5.6, 1/200s and ISO 100. Reflective silvery fish in the background become balls of light with the bokeh.
Ladybug F18, 1/125s, ISO 100. This uniquely colored amphipod was shot with the SMC-1 at full maginification. The bright and sharp EVF helped immensely with super-macro focus and composition.
The autofocus of the A7 IV when using the Sony 28-60mm with both the WACP-1 and WWL-1B was snappy and accurate, even in poor lighting conditions. For wide-angle, my tendency is to keep the focus area near the center of the frame and use the 'AF-ON' button, which is easily actuated using the dedicated thumb lever on the NA-A7IV, to trigger the autofocus. I can then recompose without worrying the camera will focus on the wrong part of the image. I never found the camera unable to quickly and accurately focus on the subject, even in poor lighting conditions such as these sweetlips at 140' on a rainy day.
Sweetlips F6.3, 1/80s and ISO 320. These sweetlips were at 140' on a rainy day. Being able to get sharp corners at F6.3 is one of the many benefits of the WACP-1. This was at 60mm focal length.
The same sweetlips at the same settings but using the 28mm focal length. The flexibility of the WACP-1 allows for capturing subjects in a variety of compositions.
The reef at Batu Rufus in Raja Ampat F8, 1/60s and ISO 320. The extremely natural look of a WACP-1 image is always most evident in reef scenics with a noticeable lack of pincushion and fisheye distortion.
Barracuda school near Tifore Island F8, 1/100s at ISO 100. The shadow detail of the A7 IV is excellent and helps with scenes like this that have a wide dynamic range.
Back tip reef shark in Halmahera F7.1, 1/125s at ISO 200. Zoomed in to 60mm with the WACP-1 and using F7.1 allows the shark to stand out from it's background.
Manta ray near the surface at Manta Sandy in Raja Ampat. F8, 1/100s at ISO 320. The small diameter of the WACP-1 and WWL-1B are excellent for snorkeling, keeping the surface area to a minimum.
Anemone and anemone fish F8, 1/60s at ISO 160. Dark days are great for creative lighting wide angle. As with macro, seeing the review in the EVF allows for lighting adjustments without having to take your eye away from the viewfinder.
Sea fan at Cape Kri in Raja Ampat F8, 1/60s at ISO 400. Even with part of the fan extending into the corner of the frame, the entire fan is extremely sharp thanks to the WACP-1 and careful focus.
A camera is only as good as the optics it is paired with. The Sony E-mount ecosystem is massive and a variety of lens and port combinations are possible to satisfy almost any shooting situation. For reef-centric imaging the flexibility, lack of distracting distortion and ultra-sharp corners of the WACP-1 and WWL-1B are unbeatable. Sony's FE 28-60mm F4-5.6 lens works with both systems. While both optics provide full zoom-through and a maximum field-of-view of 130º, the WWL-1B is a wet-optic that can be removed underwater and swapped for the CMC-1 or CMC-2 optics to capture both super-macro and larger macro subjects using the bayonet mount system.
Soft corals on a slope in Halmahera. F16, 1/250s at ISO 100. With a ~0" close focus distance, getting as close as possible to these soft corals allows good lighting of the subject by the strobes while maintaining F16, 1/250s and ISO 100 to knock down the sunball.
While we didn't focus on video, the A7 IV is also a capable video shooter, able to capture 10-bit UHD 4K at up to 60fps (with an APS-C crop) or 30p using the full field-of-view.