Fluorescence / UV Underwater Photography

Also known as: Fluoro photography, fluo diving, UV photography, NightSea photography
Key practitioners: Charles Mazel (NightSea), Norbert Wu, Alex Mustard, Alex Tyrrell, Jeff Honda, Martin Dohrn
Equipment: Blue excitation light source (e.g., NightSea, Sola Nightsea, Keldan Blue module, FireDiveGear, GlowDive), yellow barrier filter on lens port, optional yellow mask filter; macro or wide-angle lens
Key suppliers: NightSea (Charles Mazel), Light & Motion (Sola Nightsea), GlowDive, FireDiveGear, Keldan, Dyron, Fantasea

Overview

Fluorescence photography captures the phenomenon in which marine organisms absorb light at one wavelength and re-emit it at a longer wavelength, causing corals, anemones, nudibranchs, and other creatures to “glow” in vivid greens, yellows, oranges, and reds against a dark background. The technique requires specialized blue or ultraviolet excitation lights and yellow barrier filters that block the excitation wavelength while transmitting the fluorescent emission.

While fluorescence in corals has been known to science for decades, its application as an underwater photography technique developed primarily in the 2000s, driven by NightSea founder Charles Mazel’s pioneering research and the increasing availability of affordable LED excitation lights. By the 2010s, fluorescence diving had grown from a niche scientific pursuit into an accessible creative technique, with multiple manufacturers producing purpose-built equipment and community members building DIY alternatives.

History on Wetpixel

Early community interest (2002—2003)

The earliest Wetpixel discussion of fluorescence photography dates to June 2002, when forum member “lamadio” asked whether anyone had experience with NightSea accessories for photographing underwater fluorescence. Responses were mixed: one user tried it in Hawaii with minimal results, while another (“randapex”) ordered a custom NightSea filter set for his Tetra housing. By August 2002, randapex reported success photographing fluorescing anemones in Puget Sound’s Edmonds Underwater Park, though a later dive at Alki produced nothing — illustrating the location-dependent nature of the technique (^[1]).

In February 2003, randapex shared a fluorescent anemone image from Puget Sound on the Wetpixel showcase forum, explaining that the images used “special filters on the strobe and lens” and that the technique captured emitted light rather than reflected light. Community member “cybergoldfish” noted the system worked particularly well on jellyfish. Alex Mustard’s colleague Ethan Gordon in Boston had also experimented with the technique on jellies (^[2]).

Charles Mazel and the scientific foundation (2005)

Eric Cheng published a December 2005 article on Charles Mazel’s fluorescence photography research. Mazel, founder of NightSea, had published a paper in Limnology & Oceanography: Methods describing how to photograph fluorescence underwater using the right flash, filters, and digital camera with manual controls. The paper covered technique for underwater use, its limitations, and strategies for maximizing results. Alex Mustard commented that he had also published a paper on the subject in the same journal. A commenter (“scubayogi”) also shared their own fluorescence images, indicating early grassroots interest beyond the scientific community (^[3]).

DIY experimentation and GlowDive emerge (2010)

By 2010, community interest in fluorescence photography was growing rapidly, but commercial equipment remained expensive. Forum member Ed_Dman shared UV test shots taken with a DIY UV torch, and Alex Mustard responded that he had made his own fluorescence filters years earlier “from a booklet of filter samples” because he “couldn’t afford” the NightSea commercial filters. Mustard noted the technique was “very simple” to DIY, though likely with “inferior performance” (^[4]).

A parallel thread on fluorescence photography advice drew technical discussion about filter specifications, with users recommending NightSea products or suggesting alternatives like dichroic filters from Omega Optical. “blueglass” (Carlos) introduced GlowDive (glowdive.com), a new supplier of underwater UV lights and fluorescence filters, expanding the market beyond NightSea’s dominance (^[5]).

Alex Tattersall tested the GlowDive filters in Egypt in late 2010 and shared striking coral and anemone images. Alex Mustard then posted a wide-angle double-exposure fluorescence image taken with a Nikon D700 and 16mm fisheye using GlowDive filters obtained from “Alex/Carlos,” calling them “great fun” and planning to write a review (^[6]).

Fluorescence as a creative trend (2011)

By early 2011, fluorescence photography was gaining recognition as a significant creative trend in underwater imaging. In a forum discussion about photography fads, Alex Mustard noted that when Peter Rowlands (editor of Underwater Photography magazine) saw Mustard’s fluorescent coral shots in Egypt, Rowlands “commented that he’d soon be hearing the sound of hundreds of snoots landing in waste paper baskets” — suggesting fluorescence was poised to overtake snoots as the next major creative technique (^[7]).

NightSea founder Charlie Mazel attended the 2011 Digital Shootout in Bonaire alongside other industry figures, demonstrating fluorescence equipment to participants (^[8]).

Dyron and dedicated hardware (2011)

In December 2011, French manufacturer Dyron launched the Solaris 4200 UV light, a dedicated fluorescence diving light with 4,200-lumen output, 120-degree beam, and 30—50 minute burn time. It shipped with gel filter material for cutting custom mask and housing port filters, representing one of the first purpose-built fluorescence light systems beyond NightSea (^[9]).

Jeff Honda’s fluorescence video breakthrough (2012)

Wetpixel member Jeff Honda produced a landmark fluorescence video using the new Sola Nightsea lights during a Backscatter trip to Lembeh, Indonesia. Honda spent an entire week “on the night shift” capturing the footage, using a tripod exclusively because the fluorescent light was so dim compared to white light. The video drew enthusiastic community response, with comments praising the flatworm with yellow fluorescence and blue-ringed octopus footage. The discussion prompted questions about adapting the Sola Nightsea filter system to other Light & Motion lights (^[10]).

At DEMA 2012, Light & Motion representative Louis Prezelin demonstrated the Sola Nightsea system, which reporter Dave Burroughs described as lighting “up corals at night with ultraviolet light” with an integrated mask filter and camera filter system (^[11]).

Equipment becomes accessible (2013)

Light & Motion released a $99 Nightsea Flip3 fluorescence filter for the GoPro Hero3 in March 2013, marking the transition of fluorescence photography from specialist equipment to consumer accessibility. The aluminum flip-style filter attached to the GoPro housing with a single screw and could be flipped aside for conventional filming. Dr. Charles Mazel, quoted in the press release, described the Sola Nightsea as “the most advanced tool for fluorescence diving on the market,” emphasizing that it used blue LEDs with NightSea’s “proprietary interference filter” rather than simply filtering a white light (^[12]).

Alex Tyrrell’s Full Frame feature (2013)

Photographer Alex Tyrrell’s Full Frame gallery on Wetpixel showcased 29 fluorescence images from Koh Tao, Thailand, representing the most comprehensive fluorescence portfolio published on the site. Subjects included fimbriated moray eels (Gymnothorax fimbriatus), star flower coral polyps (Astreopora myriophthalma), Indian phidiana nudibranchs (Phidiana indica), urchin clingfish (Diademichthys lineatus), golden mantis shrimp (Lysiosquilloides mapia), freckled frogfish (Antennarius coccineus), mushroom corals (Fungia spp.), magnificent sea anemones (Heteractis magnifica), and various decorator and hermit crabs.

Tyrrell began fluorescence photography in 2010 in the Philippines, noting that “at the time not many divers were using this type of photographic equipment and it has only recently hit the spotlight.” He used a Nikon D7000 in a Subal housing with NightSea fluorescent filters on Sea & Sea YS-250 strobes. The gallery notably captured coral spawning under fluorescence — a rare combination of phenomena (^[13]).

Keldan modular UV and Blue modules (2014)

Swiss light manufacturer Keldan introduced UV and Blue LED modules for their Video 8M modular light system in late 2014. The UV module (5W at 400nm) produced light invisible to the human eye for fluorescence imaging without a barrier filter. The Blue module (28W at 450nm) produced a very bright beam for fluorescence imaging with a yellow barrier filter, and Keldan noted that “most marine life that fluoresces does so more intensely with blue than with UV” — an important technical distinction for practitioners. A Deep Red module (25W at 655nm) was also offered for observing nocturnal fish behavior without disturbing them (^[14]).

Martin Dohrn and bioluminescence filming (2014)

Filmmaker Martin Dohrn, who had specialized in filming bioluminescence for 25 years, helped create the Ammonite Starlight Camera specifically for filming underwater bioluminescence. Dohrn described dolphins swimming in bioluminescent waters as “probably the highlight of my career.” The article noted that approximately 80 percent of ocean species have the ability to produce light (^[15]).

Note: Bioluminescence (organisms producing their own light through chemical reactions) is distinct from biofluorescence (organisms absorbing and re-emitting external light at different wavelengths). Both techniques are discussed in the underwater photography community, sometimes interchangeably.

Norbert Wu’s fluorescence legacy (2015)

Norbert Wu featured a fluorescent coral image from Palau as the first entry in his “Favorite Images” series on Wetpixel. The image was taken on 35mm film at 80 feet depth using only ambient light — no strobe, no excitation filter — relying instead on the natural blue-shifted light at depth where “nearly all red and yellow colors have been removed from sunlight.” Wu used either a tripod or very steady hand-holding with a wide aperture and slow shutter speed.

The image had been featured on Microsoft’s Bing homepage. Wu also showed the same coral head photographed with strobe light, where the fluorescence was invisible because “the strobe light overpowers it so you don’t see it.” A Bing editorial noted that scientists “still understand very little about the function of fluorescence among corals” — theories ranged from defense against predators to UV sunscreen (^[16]).

Sandro Bocci’s coral timelapse film (2015)

Italian filmmaker Sandro Bocci released a preview of his film “Porgrave,” featuring macro timelapses of corals and aquatic life filmed under ultraviolet light. The preview film “Meanwhile” showed the marine world “at high magnification and during long time span through the timelapse,” representing an artistic application of fluorescence/UV imaging beyond traditional still photography (^[17]).

Biofluorescence discovery expands beyond corals (2015)

Marine biologist David Gruber of City University of New York discovered the first ever biofluorescent reptile — a critically endangered Hawksbill sea turtle fluorescing red and green — in the Solomon Islands in July 2015. Alexander Gaos of the Eastern Pacific Hawksbill Initiative speculated the biofluorescence could serve as camouflage. The discovery demonstrated that fluorescence research was expanding beyond corals into entirely new taxa (^[18]).

DIY movement and budget alternatives (2012—2015)

A persistent theme in Wetpixel’s fluorescence community was the high cost of commercial equipment, which spawned an active DIY subculture. Forum members built custom fluorescence lights by replacing white LEDs in cheap dive torches with royal blue (450—460nm) LEDs, and experimented with various barrier filter materials including Rosco theatrical gels, Kodak Wratten filters (#8, #12, #15), Lee lighting gels, and yellow acrylic plexiglass.

Key technical insights from the community:

• The Kodak/Tiffen Wratten #12 yellow filter emerged as the consensus barrier filter, with a sharp cutoff at approximately 500nm (^[19])
• Glass dichroic filters were too brittle for underwater use and would shatter under pressure if mounted as the front element of a dive torch (^[20])
• Plexiglass/acrylic barrier filters produced brighter, more colorful images than glass filters because they “leak” a tiny amount of blue light, creating a deep blue background rather than pure black (^[21])
• NightSea’s commercial filters remained the quality benchmark, with community member LarsB maintaining a detailed fluorescence diving reference at guest.engelschall.com

Fantasea and multi-mode lights (2015)

Fantasea released the Radiant Pro 2500 video light in 2015 with UV and Blue modes built in alongside standard white light, representing the trend toward multi-mode lights that included fluorescence capability as a feature rather than requiring separate dedicated equipment (^[22]).

Canon “See Beyond Darkness” and Andy Casagrande (2017)

Canon featured biofluorescence footage filmed by Andy Casagrande in the Solomon Islands as part of their “See Beyond Darkness” campaign showcasing low-light camera technology. The footage was shot using the Canon ME20F-SH Multipurpose Camera and EOS-1D X DSLR, demonstrating how high-sensitivity camera technology was enabling new approaches to fluorescence and bioluminescence imaging (^[23]).

Adobe/Pantone “Glowing Glowing Gone” campaign (2019)

In a notable convergence of fluorescence science and mainstream culture, Adobe and Pantone partnered with The Ocean Agency to create three custom “Glowing” coral colors — Glowing Yellow, Glowing Blue, and Glowing Purple — based on the fluorescent colors exhibited by stressed corals before bleaching. The campaign, announced during Ocean Week 2019, used imagery from coral fluorescence photographed in New Caledonia during filming of the Netflix documentary Chasing Coral. The stressed fluorescence response, described as corals “producing brightly colored chemicals that act as sunscreen in a desperate bid to survive,” was framed as “the ocean’s ultimate warning” of climate crisis (^[24]).

Wetpixel Live primer (2020)

Alex Mustard and Adam Hanlon dedicated a Wetpixel Live episode to fluorescence photography, discussing “the process and tools that are used to create images of this amazing natural process.” By this point, fluorescence photography had been covered in Wetpixel’s community for 18 years (^[25]).

Post-processing approaches (2021)

Later community discussions explored whether yellow barrier filters could be eliminated entirely in favor of post-processing to remove blue light. Forum member “Architeuthis” (Wolfgang) demonstrated that it was possible to shoot with only a blue LED light and no filter, then reduce blue and enhance yellow in Lightroom. However, the consensus remained that physical barrier filters produced far superior results because the reflected blue excitation light would otherwise “drown out” the weaker fluorescent emission — a fundamental signal-to-noise problem (^[26]).

Technique Details

How fluorescence works

Certain marine organisms contain fluorescent proteins or pigments (including Green Fluorescent Protein, or GFP) that absorb light at short wavelengths (blue or ultraviolet) and re-emit it at longer wavelengths (green, yellow, orange, red). The fluorescent emission is always at a longer wavelength than the excitation — this is Stokes’ law. The effect is most dramatic at night or in deep water where ambient blue light dominates.

As Norbert Wu’s Palau images demonstrated, natural fluorescence can sometimes be visible at depth using only ambient light, since water selectively absorbs red and yellow wavelengths while transmitting blue — essentially creating natural excitation conditions (^[27]).

Disputed: There is ongoing confusion in the underwater photography community between fluorescence and bioluminescence. Forum threads frequently conflate the two. Fluorescence requires an external light source for excitation; bioluminescence is self-generated light from chemical reactions within organisms. As NightSea’s Charles Mazel clarified, the technique uses blue excitation light, not ultraviolet, because “overall more things fluoresce, and fluoresce more brightly, when illuminated with the right blue light” compared to UV (^[28]).

Blue vs. UV excitation

A critical technical distinction that evolved through Wetpixel community discussion:

• UV excitation (360—405nm): Some organisms fluoresce under UV but not blue light. However, UV output from LED sources is relatively weak, and polycarbonate housings/ports block UV below approximately 450nm, limiting effectiveness with standard dive gear. Forum member “Basileus” tested UV-C fluorescence with a Sea & Sea YS-110a strobe and found the polycarbonate components blocked the UV wavelengths (^[29])
• Blue excitation (440—470nm): The preferred approach for most underwater fluorescence photography. NightSea’s Charles Mazel stated: “We started out with ultraviolet a long time ago, but with a combination of science and experiment learned that blue provides a far superior experience” (^[30]). Keldan’s specifications confirmed that “most marine life that fluoresces does so more intensely with blue than with UV” (^[31])
• Keldan UV module (400nm): A unique approach — true UV at a wavelength that passes through glass optics, producing fluorescence without requiring a barrier filter since the excitation light itself is invisible

Equipment setup

1. Excitation light: A blue LED torch (typically 440—470nm wavelength) aimed at the subject. The Sola Nightsea uses blue LEDs with a “proprietary interference filter that fine tunes the output for maximum viewing effect” rather than simply filtering white light (^[32]). Other options include NightSea dedicated lights, Keldan UV/Blue modules, FireDiveGear, and GlowDive products.
2. Barrier filter on lens: A yellow/orange filter (typically a Wratten #12 or equivalent with ~500nm cutoff) mounted over the camera port or lens. This blocks the reflected blue excitation light while transmitting the fluorescent emission wavelengths. Without this filter, the blue light overwhelms the fluorescence. As forum member “SwiftFF5” explained: “You are trying to photograph the light that has been re-emitted by the fluorescent organism. If you allowed the excitation light to reach the camera, it would over power the weaker fluorescence signal” (^[33]).
3. Mask filter (optional but recommended): A yellow filter over the dive mask so the photographer can see the fluorescence with their own eyes. Without it, the scene appears dominated by blue light.
4. Strobe filters: Blue excitation filters (dichroic glass) on strobes to convert white strobe light to blue excitation wavelengths. NightSea produces custom filters for Inon Z-240, Z-330, and other popular strobes. These are significantly more expensive than continuous light solutions due to the precision dichroic glass required. Forum users noted that flat GlowDive strobe filters were available at roughly 25% of the NightSea price (^[34]).
5. Filter matching: Mark Drayton (forum member “markdrayton”) emphasized that for best results, “the spectral properties of the barrier filter should be closely matched to the spectral properties of the excitation light source.” FireDiveGear deliberately designed their filters to “let a little of the blue excitation light through to the camera,” producing a deep blue rather than black background (^[35]).

Camera settings

Based on community discussion across multiple threads:

• Wide aperture (f/2.5—f/4) to capture the dim fluorescent emission
• High ISO (1600—3200+) — Mark Drayton noted that high ISOs are needed “particularly if you want to bring out the subtler oranges and reds that tend to be lower intensity than the prevalent fluoro-green”
• Slow shutter speeds for continuous light sources; faster when using filtered strobes
• Tripod recommended for video — Jeff Honda used a tripod exclusively for his Lembeh fluorescence video because “the amount of reflected light is much less than that of white light” (^[36])
• Macro preferred — close-up photography is easier than wide scenes because it is “difficult to get large amounts of light onto the subject” over wide areas

Subjects

Common fluorescing marine organisms documented by Wetpixel community members:

• Hard corals: Brain corals (Symphyllia spp.), mushroom corals (Fungia spp.), staghorn corals (Acropora spp.), star flower coral (Astreopora myriophthalma), boomerang coral (Polyphyllia talpina), lobed cup coral (Lobophyllia hemprichii), bubble coral (Physogyra lichtensteini)
• Soft corals and anemones: Magnificent sea anemones (Heteractis magnifica), corallimorphs (Corallimorphus spp.)
• Nudibranchs: Nembrotha kubaryana (fluorescent orange pigments, featured in Alex Mustard’s Wildlife Photographer of the Year award), Indian phidiana (Phidiana indica), Cuthona yamasui
• Crustaceans: Golden mantis shrimp (Lysiosquilloides mapia), Lisa’s mantis shrimp (Lysiosquillina lisa), white-spotted hermit crab (Dardanus megistos), anemone hermit crab (Dardanus pedunculatus), orangutan crab (Achaeus japonicus), hydroid decorator crab (Hyastenus bispinosus)
• Fish: Fimbriated moray eel (Gymnothorax fimbriatus), freckled frogfish (Antennarius coccineus), striped triplefin (Helcogramma striata), urchin clingfish (Diademichthys lineatus), freckled goatfish (Upeneus tragula), gobies, scorpionfish
• Cephalopods: Blue-ringed octopus (captured in Jeff Honda’s video), cuttlefish
• Other invertebrates: Flatworms (yellow fluorescence, highlighted in Honda’s video), jellyfish
• Reptiles: Hawksbill sea turtle (first biofluorescent reptile discovered, 2015)

Challenges

• Limited light: Fluorescent emission is dim, requiring wide apertures, higher ISOs, and slow shutter speeds. Video requires a tripod or very steady technique.
• Color accuracy: The barrier filter creates a color cast. Glass filters tend to produce duller images showing mainly reds and greens; acrylic/plexiglass filters produce brighter images by allowing a small amount of blue to pass, creating a more pleasing blue-black background.
• Subject finding: Many photographers need experience to develop an eye for which organisms fluoresce. Some subjects (like centipedes, as one forum member discovered during land-based filter testing) fluoresce unexpectedly.
• Night diving required: Fluorescence is most visible in darkness, adding logistical complexity. Some natural fluorescence is visible during day dives in deep water with ambient blue light, as Norbert Wu demonstrated.
• Equipment cost: NightSea dichroic strobe filters run approximately $200+ per strobe. The DIY community developed cheaper alternatives but with compromises in optical quality and reliability.
• Strobe vs. fluorescence conflict: White strobe light overpowers fluorescence. Forum member “kilili” explained that “the strobe overpowers and washes it out,” requiring either filtered strobes or continuous blue excitation lights only (^[37]).

Scientific and conservation significance

Fluorescence photography transcended creative technique to become relevant to coral reef conservation science. The 2019 Adobe/Pantone “Glowing Glowing Gone” campaign highlighted that stressed corals exhibit a distinctive fluorescence response before bleaching — producing “brightly colored chemicals that act as sunscreen in a desperate bid to survive.” This “glowing” phenomenon was described as “one of the most visual indicators of the climate crisis” by The Ocean Agency (^[38]).

The discovery of biofluorescence in Hawksbill sea turtles (2015) and ongoing research into fluorescent proteins across marine taxa demonstrated that the technique developed by underwater photographers was contributing to scientific understanding of marine biology (^[39]).

Equipment timeline

Forum discussions

Wetpixel forum threads on fluorescence spanned nearly two decades and covered the full range from beginner questions to advanced technical discussion:

• “Night Sea?” (7 replies, 2002) — The earliest community discussion, with initial skepticism giving way to successful experimentation (^[40])
• “Fluorescent anemone (drop the Hammer)” (7 replies, 2003) — Early image sharing and technique discussion; jellyfish noted as good fluorescence subjects (^[41])
• “Ultra Violet Test Shot” (9 replies, 2010) — DIY approaches; Alex Mustard shares his own homebrew fluorescence images (^[42])
• “Floresence photography advice” (10 replies, 2010—2022) — Technical filter specifications discussed; GlowDive introduced; thread remained active for 12 years (^[43])
• “Red fluorescent anemone & clown fish” (15 replies, 2011) — Challenge of capturing natural deep-water fluorescence when strobes overpower the effect (^[44])
• “Capturing Fluorescence? - Help Needed” (9 replies, 2011) — Video-specific fluorescence challenges; aquarium application; UK Light Cannon recommended for power (^[45])
• “DIY LED and UV dive lights” (13 replies, 2012—2014) — Comprehensive DIY build discussions; Princeton Tec conversions; Wratten filter comparisons; LarsB’s reference guide (^[46])
• “Cheaper blue lights for fluo diving” (6 replies, 2015) — Budget approaches with Chinese LED torches; warnings about dichroic filter pressure failures (^[47])
• “Calling Flouro experts” (27 replies, 2019) — Extensive barrier filter testing with spectral analysis; Wratten, Lee, and Rosco filter comparison; NightSea science cited (^[48])
• “Blue filter for fluo diving on Inon Z330” (7 replies, 2020) — NightSea vs. GlowDive strobe filter pricing and compatibility (^[49])
• “FIX NEO Blue Light - remove blue in post processing?” (10 replies, 2021) — Whether barrier filters can be replaced by post-processing (consensus: no) (^[50])

See also

• Light & Motion — Manufacturer of Sola Nightsea lights
• Backscatter — Retailer and trip organizer; Jeff Honda’s fluorescence video shot on Backscatter trip
• Alex Mustard — Published scientific paper on fluorescence; early DIY experimenter; Wetpixel Live primer
• Norbert Wu — Ambient-light fluorescence photography on film
• Night diving — Related technique; fluorescence photography typically requires darkness

References

Wetpixel Live