Under the right light, a whole new world of exciting colors pops up. You have probably seen the way black lights work - posters, some mini golf courses, and of course some night clubs use them. What you might not know is that you can get a UV light for diving in dim conditions, which will pick up every single trace of bioluminescence and create a wonderland of colors and exquisite shapes just waiting to be captured.
The Basics: UV Light in the Underwater Environment
To get the most out of your ultraviolet light, switch off your primary light and go completely UV - you'll see amazing things, particularly if you're on a busy coral reef. Anemones and sea stars, cup corals, and all sorts of fish and crustaceans boast at least some bioluminescent features. Shining a UV light on subjects like these stimulates that bioluminescence, much in the same way turbulence in the surrounding water can stimulate it (think about the way night time fin kicks create flashes of light, and you'll be on the right track.)
Your underwater UV light will work best and achieve the greatest results when it is completely dark, in places where no ambient light wavelengths penetrate.
Enhancing UV Light With an Orange Gel
Using orange gels with your UV lights helps to isolate your fluorescent subjects from the background. Cut one gel and place it inside your housing port. Next, you need a way to see what your camera is seeing so that you can get the shots you want. Some divers actually put orange gels inside their masks, but this makes for a dark dive and heavy fogging can occur - using a gel in your mask is really not a safe or smart tactic. Instead, you can create a viewing window with a gel. Create a frame with duct tape and connect the viewing window to a strobe arm with a lightweight lanyard. Pick it up and look through it as you compose your shots. The more you practice with this the better you'll be at getting the photos you want, and the more time you spend in a particular area, the better your results will ultimately be, as well.
Tactics for Capturing Images With UV Lights
Most of the time, you're going to be focusing heavily on macro subjects when shooting bioluminescent creatures. Doing this will provide you with the best details, and it will give you better overall results. The distance and angle of the UV light you use can have a major impact on the way your photos turn out, so if possible, hold that light by hand and shoot in AV mode. You'll find that you have a lot more flexibility this way, and since you won't be working with flash or spot meters, you can probably achieve this with some ease.
Finally, if you've got a compact camera, push your ISO up as high as it goes to capture sharp images. If you're shooting a dSLR, then you'll be able to get even crisper images, since your shutter speed has the capacity for high ISO settings. Try setting ISO at 640. Either way, remember to fill the frame, and keep on practicing. You'll be amazed at the results!