LIGHT STUDY: BLACK BACKGROUNDS
The digital era of underwater photography is in full swing with the perpetual advancements in camera technology. The seemingly endless array of new cameras, lens, and lighting options are allowing underwater photo enthusiasts to capture images in ways that were never before thought possible. Digital cameras can quite literally see in the dark with ISO values that extend to 409,600 while lenses like the Carl Zeiss Tessar f2.8/50mm generate an unusual bubble like bokeh which has become all the rage on Facebook's underwater photo groups. However, despite all these technological advancements in underwater photography equipment, there are still those shooting styles which employ very little technology, and instead rely on some good ol' fashioned precision lighting and composition. One such style that has held its ground against this digital onslaught and can still be seen kicking some A in underwater photography competitions is the illustrious black background.
As with many aspects of life, simplicity is often times the best alternative. A well chosen subject composed against a black background will draw the viewers' attention directly to the subject and not to other visual elements in the photo that may otherwise be a distraction. The photos themselves may be simple in design, but a black background can prove to be a difficult effect to achieve with your camera. You may hear people say that it's easy, you just need a quick shutter speed or a small aperture while others say it can only be done on a night dive. While both of these bits of advice are not incorrect, there are some other principals we need to take into consideration.
Black background are most frequently applied to macro subjects like nudibranchs and frogfish as a means to stylistically separate the subject from the cluttered backgrounds often accompanying critters of this sort. Without using any specialized lighting tools like snoots, we can attain fantastic black background results by simply using our strobes, we just need to first find the ideal subject. When I say ideal subject, I'm not talking about those 'holy grail' species like rhinopias or a two headed nudibranch. If it's black backgrounds you're after we need to bypass those critters residing within the chaos of the reef where intrusive backgrounds are unavoidable and seek out those subjects with access to the open water. You can have the quickest shutter speeds, the smallest apertures, and the darkest night but if your intended subject is a nudibranch crawling in front of a crinoid just a few centimeters behind, the chances of separating the two with your strobes lights become increasingly difficult. Once we've found our subject, then we can start thinking about exposure settings and strobe positions.
THE BEST SUBJECTS
Your camera settings are going to depend a lot on how much natural light there is in the water. If you're planning on shooting a frogfish with a black background in shallow, sunny, mid-afternoon water then you are going to have to use a combination of a quick shutter speed, small aperture, and the lowest your ISO can go in order to block out all that natural light. Shooting in mid-day sun can be difficult to tell if the images coming back on your LCD screen are in fact black, or just a really dark blue or green. For this I recommend using the histogram to tell if your are really getting those clean black backgrounds. Nothing is more frustrating than finding out your backgrounds are an unpleasant shade of blue with bits of reef visible instead of that crisp jet black.
At night we have a bit more flexibility when it comes to our camera settings, particularly with the aperture as we already have our natural black background so long as we've chosen wisely with our subjects! Quick shutter speeds, 1/125 or faster, are typically recommended in macro photography as anytime we use a lens with a higher magnification the more camera shake is noticed. Without having to worry about too much abut our shutter speed, and with the ISO left at it's lowest, we're left with only our aperture to play with giving us flexibility in how much depth of field we want to have with our subject.
Depending on how much space our subject has between it and the reef behind is going to be a major factor in our strobes positions. A subject with nothing but the water column behind it our are most ideal candidate. In situations like this we simply need to adjust our exposure settings to block out the natural light and then illuminate our subject with our strobes. Keep in mind black backgrounds have a tendency to show backscatter a lot easier than reef backgrounds so pay make sure your strobes are behind your lens. The power of your strobes will be influenced by how far away your subject is from your camera but also with how much natural light you've had to block out with your exposure settings. The further a subject is and the more natural light you have to block through your exposure settings, the higher your strobe's power settings need to be.
When we have a subject where the reef behind it could potentially ruin our black background should our strobe light reach there, we need to adopt a slightly different strobe technique called inward lighting. The basic idea of inward lighting is to have our strobes facing towards our camera rather than just slightly out. By adopting this inward strobe angle we will be cutting out any background subjects that might otherwise be illuminated with a slightly outward strobe angle.
First of all what is a snoot and how does one go snooting? The basic idea of a snoot, in function, is to take that wide beam of your strobe and narrow it down into a much more controlled beam with a diameter varying from three inches or so down to a centimeter. In design they vary significantly, from flexible fiber optic arms to tapered metal tubes, all of which mount to the front of your strobe. There is even the DIY version where people, including myself, have built them out of household materials like the hollow center column in a DVD spindle, old wetsuits, and plumbing PVC. The benefit of a snoot is that with such a controllable and narrow beam of light we no longer need to bypass those little critters hiding amongst the reef where black backgrounds are not otherwise possible.
Through the pinpoint accuracy of the snoot's light and the varying beam diameters, we have quite a wide range of subjects to select from. Depending on your subject and it's size, we can choose to either have the light fall over the entire subject or just single out specific attributes of a subject to highlight, such as the eye of a crocodile fish. While our range of shootable subjects with a black background has increased significantly with the addition of a snoot, there is one piece of criteria I follow when I'm looking for something to snoot, and that is that it is stationary! Since we are working with a much smaller beam or light it becomes more and more difficult to get the actual light on the subject. Just because you can see the subject in the viewfinder doesn't mean your snoots beam is aligned. Even a moving nudibranch can be a bit too quick! At least until you get the hang of snooting I suggest starting with simple, non moving subjects.
STROBE POSITION AND MOUNTING
Before we begin worrying about how we are going to light our subject though, it's important to think about how and where you want to have your snooted strobe mounted, or if you wanted it mounted at all. There are two main options for using snoots and no real right or wrong to either, it just comes down to personal preference.
I won't lie, black backgrounds can be more time consuming than your standard macro photos or 'bokeh' (shallow depth of field) photos, especially in the beginning. With time though you learn to spot the subjects where, with minimal effort, you can get the results you want. Though black backgrounds may be more troublesome to get, the results will add a new dimension to your portfolio and really help draw attention to your work despite the lack of highly specialized camera equipment.