Off camera strobes

Adding depth to underwater photography

One of the greatest differences when moving from ocean diving photography to cave diving photography is that the background sunlight has been taken out of the picture. Unlike the movies and unless you’re playing in the cavern zone, the only light underground is that which you bring with you. While the darkness provides great opportunities to try new lighting techniques, it also presents a few difficulties. I’m going to briefly outline the tricks I’ve used over the last two years to get some of my favourite cave diving photos.

As underwater photographers already know, strobe light doesn’t travel very far from the source. In caves, if your only strobes are the ones attached to your camera, this limits you to lighting things within approximately 10 feet. The distance here depends heavily on strobe power and water clarity, and practically it often means the second diver in the shot is a pair of eyeballs and possibly some tank valves floating in the blackness.

Strobes attached to the camera are convenient and necessary but usually not sufficient for great cave photos. In particular, using only on camera strobes means that all of the light in your picture is coming from one direction. This makes for flat photos which can be otherwise technically perfect, have interesting subjects and great composition, but are somehow missing that wow factor.

Adding off camera lighting to your shot is the way to go. Luckily, this is easier than it used to be with several manufacturers making remote slave sensors. Ikelite has proprietary ones for their strobes, and I use the triggerfish sensors. Heinrichs-Weikamp also sell the RSU-N which works well in complete darkness. These sensors are connected to the off camera strobe with the same cable you would use to connect that strobe to the camera. The flash from your on-camera strobes is detected by the sensor, which triggers the off camera strobe and lights your picture.

This system works reliably for me without requiring a physical connection between the strobes and the camera. As long as the sensor can “see” the camera flash, and isn’t overwhelmed by being too close to a primary dive light or ambient sunlight, the off camera strobe fires. Once you’ve got your set-up working, the next step is thinking about placement of the strobe, and direction and power of the light it produces.

Adding more strobes to your picture does increase the difficulty level. A strobe pointed at the camera, or one that is too close to a diver or wall and creates a giant hotspot can ruin an otherwise perfect picture. Strobes that point straight down the middle of really large tunnels with black walls might as well not have gone off. Getting the right amount of strobe light in the background of your shots is half of the battle, and here’s where your buddy comes into the picture.

For larger caves and careful buddies, backmounted twin tanks are the perfect place for extra strobes. By running the cable over your model’s shoulder and hooking it into the front of their harness arrangement, no extra hands are required. [Photo 5] By looking at where your diver is pointing, you know which direction the light will be in. You can safely take photos of their smiling face, with the strobe on their back lighting up the tunnel or second diver behind. Depending on the trim of the diver and of the camera the strobe may well be entirely hidden in your photos.

Unfortunately taking photos from above and behind the diver becomes impossible, as most strobes have a light sensor built in to the face of the unit that will trigger a flash. Once you’ve experimented with sticking strobes on different parts of the diver, the next option for greater flexibility in camera angles is to give the strobe to your buddy to hold. This reduces the chance of your strobe impacting the roof, but introduces a whole new set of challenges for your model. They now need to co-ordinate the direction of the sensor towards you and the direction of the strobe away from you, while holding the setup in such a way that often they won’t know if the strobe has fired or not.

When diving with well-trained, knowledgeable and patient underwater cave models (not that I’m asking for much!), hand held off camera strobes give great results. You have the flexibility to light specific features of the cave, to take photos of your divers from any angle, and to take advantage of opportunities for great backlighting. On the other hand, you’ve just increased the task loading on your buddy and reduced the number of hands they have available for dealing with routine cave diving tasks, like talking to you.

To get successful photos from these dives, patience, co-operation and understanding is required on both sides. Discuss the aims of your day to determine if your buddy really wants to commit to a photographic dive, or if they’d prefer to swim around and enjoy the cave. Once you’re both on the same page, discussing the shots you’d like to get and working out the essential (one-handed) signals in advance will make a big difference to your results.

From here, of course, there are lots of variations for achieving great lighting effects . Have fun and experiment, and remember not to ignore your gauges in search of the perfect shot.