Master the Light: A Guide to Off-Camera Strobes and Backlighting

In this article adapted from The Underwater Photography Show, we cover the fascinating and highly rewarding technique of backlighting and using an off-camera strobe. While it is a challenging technique that takes your underwater photography to the next level. And backlighting is definitely a technique that has not been tried on many subjects, so there is much potential to create memorable images. Mastering this skill allows you to produce striking images that immediately stand out, signaling to your audience that you have gone beyond simply recording what you saw. Below, we break down the exact gear setup and shooting approaches needed for both wide-angle and macro imagery.

Wide-Angle Backlighting: Gear and Setup

The biggest misconception about off-camera strobe work is that it is a good way to repurpose an old, retired strobe. This is a mistake. Your off-camera strobe acts as the main light source for the shot, meaning it needs to be your most powerful and widest-angle light. You should actually sacrifice one of your primary on-camera strobes to use as your off-camera strobe. Powerful lithium-ion strobes—such as the Backscatter HF-1 or the Retra Maxi—are perfect for this because they allow you to blast away on high power with fast recycle times.

To successfully deploy a wide-angle remote strobe setup, you need the right framework to position, secure, and trigger the light:

• Weighting: If your strobe is inherently buoyant or light in the water (like the Retra Maxi), you will need to add a small amount of weight to keep it stable. You don't need a heavy weight belt; the smallest diving weight clipped to a cable-tie loop on the strobe works perfectly. More negative strobes like the HF-1, won’t require extra weight.

• The Gorillapod Mount: A plastic Gorillapod is ideal because it is lightweight and highly adjustable. Add a standard underwater strobe-ball mount to the tripod mount on the Gorillapod (which come with a standard quarter-inch thread). Secure the strobe to the ball mount using a standard strobe clamp.

• Transportation: To safely carry the setup during your descent, attach a loop of bungee cord and a standard dive clip to the Gorillapod so you can secure it to your BCD instead of letting it dangle.

• The Triggering System: For the best results, the off-camera strobe itself must be completely hidden from the camera's perspective so that the viewer only sees the light it produces. Because it is hidden, it will be hard to trigger. So you need a sensor and cable. You will need a straight fiber-optic cable (ideally 1 to 2 meters long) plugged into the remote strobe at one end, and a dedicated strobe trigger sensor (such as the Anglerfish) at the other end. I also attach a loop on bungee to the Anglerfish so I can carry it separately and don’t lose it.

• Sensor Positioning: Place the small sensor in a subtle spot on the seabed where it has a clear line of sight to your camera. When you fire your camera's strobes on low power, the sensor detects the flash, fires an internal LED, and sends the signal down the straight cable to fire the remote strobe (hidden from the camera) on high power. Test everything is working pre-dive, as it is very annoying to have a problem when you’ve gone to the effort of setting it all up underwater.

Shooting Strategy and Camera Settings

When shooting wide-angle with an off-camera setup, your primary creative decision is whether you want a pure backlit rim effect or if you want the remote strobe to point forward to selectively front-light a subject hidden in the dark (such as an interior feature of a large shipwreck).

Because the remote strobe is positioned much closer to the subject than you are, its beam will not cover the entire scene. You must compose your shot around what you choose to selectively illuminate. The position of the subjects of interest will also dictate what is possible.

Because the remote strobe is hidden from the camera, these shots are often light limited.

• ISO and Aperture: Work at a slightly higher ISO than normal and open your aperture a click or two wider than usual to maximize the camera's sensitivity to the remote flash.

• Shutter Speed: Because of the higher ISO and wider aperture, if you are shooting in a bright environment, you will need to employ a fast shutter speed to keep the ambient background light fully controlled and prevent overexposure.

• Strobe Power: Keep the remote strobe set to full power or a click or two below it. Rather than constantly swimming back and forth to adjust the strobe's manual power dial, leave the strobe static and adjust your exposure via your camera's aperture and ISO values.

Team Shooting vs. Diver-Held Backlighting

Setting up an off-camera strobe on a Gorillapod can be intensive; you have to swim out, set it up, swim back, adjust, and handle instances where the tripod tips over or isn’t aimed quite right. If you want to elevate the complexity with multiple strobes we strongly recommend working as a team.

Multi-Strobe Team Shooting

In workshop environments—such as lighting up the cargo trucks inside the Thistlegorm wreck—photographers can descend as a coordinated team. Each diver brings their camera alongside one remote strobe setup. By deploying multiple strobes, you can balance the exposure across a massive distance by varying the power settings relative to the camera:

• Furthest strobe: Set to full power.

• Middle strobe: Set to full power minus one click.

• Closest strobe: Set to full power minus two clicks. This results in beautifully balanced, even lighting throughout the depth of the frame.

An alternative to using a static tripod is handing the remote strobe to a buddy or a dive guide. While continuous video lights are popular for this in cave photography, they are rarely powerful enough to compete with natural sunlight in open water. Using a high-powered strobe like the HF-1 pretty much gives you the best of both. You can turn on its built-in video light so your lighting assistant can see exactly where the beam is aimed, and then you get the punch of flash when it is triggered. A good use of this approach is backlighting a diver in mid-water, having one diver as the model and a second diver directly behind doing the lighting. Frame your shot by waiting until the model’s body completely obscures the the video light, and shoot. This creates a pristine, glowing rim-light effect around the subject. It allows you to move rapidly through an environment, capturing successive creative shots without stopping to plant a tripod.

Backlighting for Macro Photography

When it comes to macro photography, deploying remote strobes on tripods or muck sticks, is largely unnecessary and rarely done the real world. Instead, macro backlighting is best achieved using your on camera strobes or by or working directly with a skilled dive guide.

The Long-Arm Method

If you want to maintain complete artistic control without relying on a guide to hold a light, configure your housing with long strobe arms than typically used for macro. By utilizing super-long arms, you can physically wrap one of your own strobes all the
way behind a macro subject on the seabed.

When planning a macro backlight session, it helps to shoot with a shorter focal length lens, such as a 50mm or 60mm lens, rather than a 90mm or 105mm macro lens. The wider perspective of a 50mm or 60mm lens shortens your working distance making it easier to reach beyond the subject with your strobe arms.

The Dive Guide and Torch Approach

In popular muck diving destinations (like Lembeh, Bali, or the Philippines), the reality is that many photographers unbolt one of their on-camera strobes, stretch out the synced optical cable, and hand it to a highly skilled dive guide who knows exactly how to aim a snoot to backlight a subject.

Alternatively, because almost all dive torches are negatively buoyant, they can easily be rested on the seabed behind a critter to create a backlight. To ensure a photography judge or viewer registers your technical effort, you can even apply colored filters to these backlighting torches. While backlight can sometimes be so subtle that the viewer doesn't explicitly realize why they prefer the image, a splash of color makes your creative choices instantly overt.

Practical Advice for Progression

Backlighting creates a dramatic difference, even when applied with restraint. When you first begin practicing, it is completely natural to use the effect unsubtly because you want the world to see how hard you worked to get the shot. However, as your eye develops, you will find that transitioning to a subtle, polished rim light is what truly elevates an image, leaving viewers wondering exactly why your photo has an impact that others lack.

Finally, a word of warning. Backlighting with remote strobes is a task loaded activity and can easily distract you from diving safely. Do not attempt this technique for the first time on a high-stakes, deep wreck dive or inside a complex cave system. Instead, dial in your settings in a highly controlled environment. Take your housing, your Gorillapod, and your sensors into a shallow swimming pool or a shallow reef to build your skills. Getting your settings fully sorted and becoming comfortable handling the components in the shallows ensures you are entirely prepared to execute the shots safely and efficiently when you dive on those classic sites.

To see the full episode, check it out here: