Articles

In this two-part article, physicist and underwater photographer Lynn Miner of Fire Dive Gear discusses the science and art of fluorescence photography. In this second installment, he looks at setup configurations, techniques, and the wide range of exciting images it’s possible to obtain
 

A daytime fluoro image of an anemone, Palau, captured with the Canon EOS Rebel T4i and Fire Dive Gear Galaxy Torch (Settings: f/14, 1/100s, ISO 800)
 

While the science behind fluorescence is complex and not completely understood, the effect can be captured by any underwater photographer willing to invest a modest amount in the required supplementary gear—and put in lots of time to try out different setups, lighting options, and target subjects. If you start with the general advice here and experiment, you will eventually get some satisfying results.
 

Setup Configurations

No two setups are the same, so it takes a bit of experimentation to figure out a configuration that works well for you. I have used both DSLR and point-and-shoot cameras to great effect. It comes down more to lighting than anything else. Obviously, a DSLR has greater flexibility in terms of optics, but one can get some amazing images with a compact.

Developed in partnership with Fire Dive Gear, SeaLife’s Sea Dragon Fluoro-Dual Beam (left) features an integrated dichroic filter. SeaLife’s Sea Dragon Flash (right) is fitted with a Fire Dive Gear excitation filter
 

At a minimum, you’ll need the following extra gear:

• a small torch to find the fluorescing targets (also works as a focus light)
• a mask barrier filter (without it, the entire reef looks blue)
• a camera barrier filter, either inside or outside your housing
• a blue light source—either a video light or a strobe with an excitation filter

Obviously, if your camera barrier filter is mounted directly on the lens inside the housing, you’re only going to do fluoro photography on that dive. If you want to switch easily between fluoro and regular photography on the same dive, you can get “flip” barrier filters for your housing as well as “flip” excitation filters for your strobes.
 

A daytime fluoro image of star coral, Palau, captured with the Canon EOS Rebel T4i and Fire Dive Gear Galaxy Torch (Settings: f/14, 1/100s, ISO 800)
 

A daytime fluoro image of star coral, Roatán, Honduras, captured with the SeaLife DC2000 and Sea Dragon Digital Universal Flash (Settings: f/5, 1/125s, ISO 800)
 

A nighttime fluoro image of an anemone, Cozumel, Mexico, captured with the SeaLife DC2000, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/6.3, 1/125s, ISO 800)

Night vs. Daylight Shooting

Fluoro diving originally started out as a nighttime only activity, but this is no longer the case. Clearly, you won’t be able to capture fluorescence in 30 feet of clear water on top of the reef at noon no matter how much power you are carrying with you. The targets will indeed fluoresce, but it will simply be overwhelmed by the ambient light.

However, on the back side of a wall with depressions and the sun in front of you and perhaps with a bit of a cloudy sky, you can find some stunning examples of fluorescing targets and still have good visual acuity. Under ledges and around a large outcropping are also good places to find subjects.
 

Strobes vs. Continuous Lights

The biggest advantage of strobes is the output power available. This allows you to stop the aperture down to enhance the depth of field. Strobes are usually easier to use, but you will still need a small handheld or rack-mounted blue light torch to find your fluorescing targets. The torch can also be used to eliminate shadows from the strobe because it’s on during the entire process.

Using blue output continuous lights has the advantage of immediacy—allowing you to photograph exactly what you’re seeing. A common technique is to have a small blue focus light mounted to your rack and use a handheld high-power blue video light. Holding the video light in your left hand may seem cumbersome, but it allows you to move the light around, in or out, as needed to get the shadows, colors and exposure you’re after.
 

A daytime fluoro image of a pipefish, Raja Ampat, Indonesia, captured with the Canon PowerShot G16 and Sea Dragon Fluoro-Dual Beam (Settings: f/3.5, 1/1600s, ISO 1250)
 

A daytime fluoro image of an anemone crab, Kapalai, Malaysia, captured with the SeaLife DC2000, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/5, 1/125s, ISO 400)
 

A nighttime fluoro image of a flatworm, Kapalai, Malaysia, captured with the SeaLife DC2000, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/5, 1/125s, ISO 200)

Macro Fluorescence Photography

Macro is by far the easiest and most rewarding way to shoot fluoro images. A target organism that appears to be various shades of beige or brown under white light can explode with all the colors of the rainbow under blue light. The color of some things may even shock you: Everyone knows what a scorpionfish looks like under white light—they’re almost invisible—but shine a blue torch on them and they light up red like a stop sign.

The emitted fluorescence is very faint, so that means slow shutter speeds and wide apertures. My preference is to use a video light and shoot Aperture Priority. Don’t crank up the ISO too much to avoid introducing perceptible digital noise. Try capturing as much depth of field as possible, but don’t stop down too much or camera shake will become a problem with very slow shutter speeds. The increased power that comes with using flash will take care of camera shake and allow a higher f-stop, but use dual strobes to avoid creating shadows, if possible.

Auto vs. manual focus is another consideration. With a low f-stop, the narrow depth of field will be problematic with manual focus unless you are absolutely stationary. Autofocus can be advantageous as long as you’re using fast-focusing lenses. With slow shutter speeds and near wide-open aperture, the slightest current or surge will cause trouble if your autofocus is sluggish.
 

A daytime fluoro image of an alligatorfish, Raja Ampat, Indonesia, captured with the Canon PowerShot G16 and Sea Dragon Fluoro-Dual Beam (Settings: f/1.8, 1/60s, ISO 200)
 

A daytime fluoro image of a shrimp on an anemone, Roatán, Honduras, captured with the SeaLife DC2000, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/5, 1/125s, ISO 800)
 

A daytime fluoro image of a fireworm, Cozumel, Mexico, captured with the SeaLife DC2000, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/6.3, 1/125s, ISO 800)

Wide-Angle Fluorescence Photography

A wide-angle scene can’t be lit in the conventional way, because excitation filters greatly reduce the power of your strobes (by about 80%). Instead, you have to set up your camera on a tripod, open the shutter, and swim around with your torch(es), “painting” the reef with light—all while staying out of the field of view of the lens.
 

Fluorescence Videography

Video can be very challenging mostly because it requires a great deal of light. This is easily solvable by using high-power lighting equipment, but if there is a lot of plankton or organic matter in the water, it will fluoresce green. This means the water will light up as well as your target—which makes for a less-than-impressive video. It’s not an issue for macro video, but unless you have crystal-clear visibility (which is rarely the case), wide-angle video is impractical.
 

A daytime fluoro image of a beaded anemone, Roatán, Honduras, captured with the Canon PowerShot G7X, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/10, 1/80s, ISO 800)
 

A nighttime fluoro image of a hermit crab, Raja Ampat, Indonesia, captured with the Canon PowerShot G16, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/1.8, 1/60s, ISO 200)
 

A nighttime fluoro image of a scorpionfish, Raja Ampat, Indonesia, captured with the Canon PowerShot G16, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/5, 1/80s, ISO 1250)
 

A nighttime fluoro image of a sea star shrimp on a Spanish dancer, Raja Ampat, Indonesia, captured with the Canon PowerShot G16, Sea Dragon Digital Universal Flash, and Sea Dragon Fluoro-Dual Beam (Settings: f/1.8, 1/60s, ISO 200)
 

A daytime fluoro image of acoel flatworms on bubble coral, Puerto Galera, Philippines, captured with the Canon PowerShot G16 and Sea Dragon Fluoro-Dual Beam (Settings: f/4.5, 1/40s, ISO 1000)
 

A nighttime fluoro image of a tube anemone, Kasawari, Indonesia, captured with the Canon PowerShot G16 and Sea Dragon Fluoro-Dual Beam (Settings: f/2.2, 1/60s, ISO 200)
 

See also Part I, where we considered the physics and biology behind the fluorescence effect, and the technology you need to capture the phenomenon.
 

About the Author: Lynn Miner is a physicist and the co-founder of Fire Dive Gear, which manufactures precision fluorescence dive gear. He has recently worked with SeaLife Cameras to develop their line of underwater fluorescent lights. Originally NAUI certified in 1973, Lynn is a SSI Instructor Trainer, PADI Master Instructor, HSA Course Director, DAN instructor Trainer, and SDI/TDI Instructor.