Underwater photography is a tricky thing to master, but one of the most important aspects is light. Water sucks the life out of light turning it a dull blueish hue within a couple of metres from the surface.
All the best underwater photographs are produced with the aid of artificial light (unless they are right at the surface). Land photographers know the kit we use as flashguns, but to use aquatic types, they are strobes… and they give life to our pictures.
Flash puts the light back into an underwater scene, so every underwater photographer needs to know how to use it effectively.
Underwater flashguns are sort of like land flashguns, only they are waterproof of course. They have an on and off switch, and a power dial (not many have LCD screens as using displays with gloves on its hard, dials are better). There are a handful of makers and you can even buy housings for terrestrial flash units. They are though, all expensive. There isn’t really a ‘cheap’ way of using a flashgun underwater, so it’s best to understand that before walking into a shop and asking how much.
Makes to look out for include Sea&Sea, a Japanese company with a long pedigree of producing great underwater photo gear. Inon, who are younger, but have still be around a while and produce some great gear too. And Ikelite who like the previous two make great quality equipment. I have used and broken all three main makes and I would recommend them all. There are also a host of slightly cheaper makers which I cannot vouch for, but in my view you really do get what you pay for.
There are strobes with different power outputs and strobes with one flash head up to three flash heads, some have a sort of ringflash built in and it’s hard to say one is better than the other. Personally I love and still use the defunct Sea&Sea YS110 range which have three flash heads angled out in a triangular pattern. I love them because they give a consistent and broad light. So your choice should be personal to you.
The strobes are connected to your camera housing with arms. Arms can be fixed or flexible. I prefer fixed arms with joints which allow me to achieve different flash angles. There’s also the choice of having the strobes wired into the camera housing or fibre optically triggered. This system uses your camera’s onboard flash, which triggers the strobe through a fibre optic cable.
These days you can put everything on auto and shoot away and get acceptable results, but if you really want to dazzle, then you need to flip over to manual and play creator. Most serious underwater photographers use two flashguns, positioned either side of the underwater camera housing. So you have three elements to play with: the light from each strobe and the ambient light around you. You control the first two and with your camera, controls how the third looks.
There are basically two ways to shoot underwater: wide angle and macro.
Wide angle: To get the better images with wide angle lenses use your strobes in combination with the ambient light. Set the exposure to keep some or all the detail in the ambient light. I actually prefer about a stop underexposed to push some contrast into an image, but whatever works for the look you are trying to achieve. Then the secret is to set each strobe to make the subject look naturally lit, even through it’s not. You could go for the same flash setting from both guns, but I often prefer a main light and a fill (lower powered) light. So I will swim around adjusting the strobes throughout the dive. The danger here is you forget on the most critical shot of the dive and mess it up.
Most high-end strobes have a number of power settings much like a terrestrial flashgun. You can dial in around 12 power settings to get the balance right. When you start off a lot of times it is hit and miss, so don’t expect award winning images to flood out of your camera (pardon the pun).
Macro photography: This is all about picking your subject out from the background. Tiny critters abound underwater and shot in close-up make beautiful images. Getting the light positioned correctly and at the right power when working with an animal the size of your little fingernail is not as easy as the pros make it look. And it’s the strobe position which will shape the light.
Many photographers opt for the side by side approach which gives a good spread of light, which works well in most situations, although the lighting can be bland. When shooting reef scenes or what’s referred to a close-focus wide-angle, I like to lift one strobe above to mimic the light coming down from the sun. It adds a dimension to the images that flat light doesn’t have.
A word of caution though about strobe positioning. Light is refracted when it moves through different mediums. So objects underwater when viewed through a mask look larger and nearer. If you position the strobe to where you think the subject is, you may be positioning it it too near and the subject is actually further back. That’s why many strobes have small lights inside. They are primarily used as focusing aids, but are also good for aiming the light correctly. I always thought a small laser pointing type light would be good, but don’t know of a strobe with one.
That is just a touch of underwater flash photography. It’s very similar in principle to terrestrial strobe photography, but with a few added dimensions.