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The author would like to thank Backscatter for supplying Backscatter Hybrid Flash Excitation Filters, Backscatter Video Light Excitation Filters, and various yellow barrier filters used in this review.
I slipped beneath the warm evening waters off Lauderdale-by-the-Sea in southern Florida, my camera rig fitted with the Backscatter Fluorescence Filter System. Within moments, the reef shifted from muted twilight tones to a glowing carnival of greens, oranges, and reds. Corals lit up like neon signs, anemones shimmered gold, and even a normally camouflaged scorpionfish revealed brilliant, hidden patterns. I’ve dived this site countless times, but the Backscater fluoro system made me feel like I was discovering it all over again!
Invertebrates without eyes, like these cup corals, have the strongest fluorescence and can be photographed at lower, more reasonable ISOs (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Nauticam SMC-3, Backscatter Fluorescence Filter System with dual Backscatter HF-1 strobes, f/18, 1/160s, ISO 800)
System Overview
The fluoro kit includes two key components: (i) blue excitation filters for your Backscatter Hybrid Flash strobes or blue excitation filters for your Backscatter Macro Wide 4300 video lights, and (ii) yellow barrier filters for your lens and mask. The excitation filters shift the strobe light to around 450nm blue, triggering fluorescence in corals, invertebrates, and certain fish species. The barrier filter blocks the blue light from reaching the camera, isolating the subject’s glow and preventing any other spectra from bleeding into the image.
The author’s Nauticam Sony a7R Mark III rig, complete with dual Backscatter MW-4300 video lights, dual Backscatter HF-1 strobes, and the Backscatter Fluorescence Filter System
I tested the system using my Hybrid Flash (HF-1) strobes and MW-4300 video lights, with a 67mm yellow barrier filter on my macro port and Backscatter Yellow Barrier Filter Dive Mask to help spot subjects. The filters are solidly built, easy to handle with gloves, and all come equipped with tethers to prevent accidental loss. The mask filter is especially helpful for scanning the dive site, though its slight positive buoyancy means it can float away if dislodged. The acrylic of the mask filter is cut in a way to fit comfortably over every dive mask: Not only could it fit over my huge single lens mask, but it wasn’t too big to be used over my wife’s low volume freedive mask.
A pleasant side effect of the yellow mask filter was a marked increase in visual contrast. Several times, I found myself easily navigating by moonlight, only to realize I was in near-total murky darkness once I removed the mask filter. This will remain a useful tool for night dives, even when I’m not planning to shoot fluorescence imagery.
Ordinarily, extremely cryptic nudibranchs like Lomanotus vermiformis look exactly like the hydroid homes they live and feed on. However, under 450nm light they become much, much easier to see! (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Nauticam SMC-3, Backscatter Fluorescence Filter System with dual Backscatter HF-1 strobes, f/18, 1/160s, ISO 3200)
Setup and Handling
Swapping the excitation filters is a breeze. They click easily and securely into the bayonet mounts on the HF-1 or slip snugly onto the MW-4300. The barrier filter threads onto the lens port like any standard 67mm filter.
The light emitted by fluorescing subjects is much weaker than the reflected white light most of us are used to photographing, and as such our camera’s autofocus can struggle. Fortunately, strong sources of constant light, such as the HF-1’s built-in spotting and video lights or the MW-4300’s beam, provide enough energy to bring out even faint fluorescence, helping autofocus work reliably. For critical shots, manual focus combined with focus peaking is very effective.
Although not officially recommended, I found the Backscatter Mini Flash 2 strobes surprisingly capable for close-range fluorescence work—great news for one of the most popular strobes in the world! The included tethers for the MW-4300s’ excitation filters allowed me to easily remove them mid-dive to access red or white light, without risk of losing the filters.
The 67mm threaded yellow barrier filter was ubiquitous in that I could easily screw it onto a variety of accessories including my flip adapter, my Nauticam MFO-1, and Nauticam SMC-3 Super Macro Converter, which all produced sharp images with the filter in front. One thing to note is that if you choose to stack the filter in front of a wet lens, you must “burp” it shortly after getting in the water, as air and water droplets will be caught between the filter and the lens.
The Atlantic’s version of the hairy frogfish is every local underwater photographer’s favorite subject—and it turns out they glow! The esca at the end of their lure fluoresces a brilliant orange. Normally, a red focus light is used in order to keep the frogfish comfortable enough to hunt in front of a photographer, but in this case a red light can overpower your barrier filter and ruin the fluoro effect. Most fish are hyper-sensitive to the 450nm light coming from any blue-UV sources, so I needed to wait for this behavior in total darkness after having focused on my thumb facing away from the subject (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Nauticam MFO-1, Backscatter Fluorescence Filter System with dual Backscatter HF-1 strobes, f/11, 1/160s, ISO 4000)
A mating pair of flame box crabs (Calappa flammea) show off intricate patterns of fluorescing proteins (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Nauticam MFO-1, Backscatter Fluorescence Filter System with dual Backscatter HF-1 strobes, f/11, 1/160s, ISO 4000)
In-Water Performance
During my time with the fluoro rig in South Florida, the system revealed glowing brain corals, electric tube anemones, and even fish eyes flashing red or green. The HF-1s provided strong, even coverage, which could induce fluorescence in subjects that weaker lights might miss. Imaging the fluorescent light created by the subjects is fainter than the direct reflected light in normal photography; additionally, the yellow fluoro filters cut a lot of light. Even with high-powered flashes, pushing the ISO higher is required for the full spectrum of fluorescence to show up in pictures.
The best results for me were achieved by having my strobes as close to the subject as possible. Backscatter doesn't fluoresce, so using “brute force” with strong lighting won't cause a backscatter bonanza. I found myself using ISO 800–1200 for stationary subjects like anemones and corals, which tended to fluoresce a bright green; and ISO 3200–4000 for mobile subjects like fish, which were likely to have purple or red fluorescing highlights. Generally, I used f/8–f/11 for my apertures and a 1/160s shutter speed. These settings are not prescriptive and could be compromised a bit to lower the ISO for most subjects, but I found several of my local muck critters to have subtle red fluorescent highlights, which I could balance against the strongly fluorescing green by lowering my strobe power to half and increasing the ISO.
A reliable starting point is f/8–f/11, 1/160s, ISO 800–4000, with strobes at high power. This usually means the “F” setting for the HF-1 and power setting 7 on the MF-2. The +2 setting on the HF-1 was a nice tool to have if I wanted to squeeze out some extra fluorescence from subjects that only fluoresced lightly like fish. The RAW files come out rich in color and contrast with minimal post-processing needed.
I also mounted the MW-4300s with a 67mm barrier filter on a Divevolk smartphone housing. Even with a smartphone, the colors were vivid and the detail crisp—proving this system works well for a whole spectrum of camera rigs!
Tube anemones are a popular fluoro subject. They sport great textures and have extremely strong fluorescence, perhaps to lure in prey? Their aggressive fluorescence meant I could keep my ISO considerably lower than while shooting most other subjects, even while using weaker-powered strobes (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Backscatter Fluorescence Filter System with dual Backscatter MF-2 strobes, Nauticam SMC-3, f/18, 1/160s, ISO 800)
Practical Considerations for Wide-Angle Fluorescence
To test the wide-angle potential of the fluorescence system, I adapted a Sony FE 28-60mm f/4–5.6 lens with a smaller yellow barrier filter and paired it with the Nauticam WWL-1. This setup delivered excellent coverage, with fluorescence excitation reaching about 5 feet from the HF-1 strobes at full power, and nearly 6.5 feet on the stronger +2 setting.
At higher output levels, the excitation filters behave differently from typical diffusers. They produce a noticeable ring of reflected white light around the edge of the illuminated area. To compensate, you’ll need to position the strobes farther behind the port or lower their power slightly. The good news is that even at reduced output, there’s still plenty of light for wide scenes. For macro and close-focus wide angle, the ring artifact is a non-issue, making the system very reliable in those scenarios.
Crustaceans like this horseshoe crab are highly fluorescent. It can be surprising to see such a beacon scurry across the seabed in the pitch black. Visible in this image are the light rings produced when using the strobes on very high power for wide angle (Sony a7R Mark III, Sony FE 28–60mm f/4–5.6, Nauticam WWL-1, Backscatter Fluorescence Filter System with dual Backscatter HF-1 strobes, f/11, 1/160s, ISO 1200)
Final Thoughts
Underwater fluorescence has given me a way to rediscover my local dive sites with fresh eyes. After years of feeling familiar with the same reefs, fish, and corals, adding a fluorescence system transformed the experience into something novel and engaging. What I once thought of as “the usual suspects” suddenly carried hidden layers of pattern and color that only revealed themselves under excitation light.
From a practical standpoint, on a single dive, I can capture the behavior and detail I’m used to, then switch over and document the secret fluorescent palette that normally goes unseen. That versatility means I can stretch a dive site further, photograph the same subjects in multiple ways, and come away feeling as though I’ve visited somewhere entirely new.
If you’re looking for a way to break creative ruts, expand your portfolio, or simply remind yourself why you fell in love with diving in the first place, the Backscatter Fluorescence Filter System delivers on its promise: easy setup, durable build, and the thrill of making your regular dive site completely new again. For HF-1, MW-4300 (and even MF-2) users, it’s a must-try addition to any well-rounded macro photographer’s bag of tricks.
Hermit crabs and the encrusting sponges on their shells provide a nice contrast of yellows and reds (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Nauticam MFO-1, Backscatter Fluorescence Filter System with dual Backscatter MF-2 strobes, f/11, 1/160s, ISO 3000)
It seems the more camouflaged the fish, the brighter it shines! Plumed scorpionfish are normally a drab, well-camouflaged brown, but when under a fluoro system, they emit a spectacular red color (Sony a7R Mark III, Sony FE 90mm f/2.8 Macro, Backscatter Fluorescence Filter System with dual Backscatter MF-2 strobes, Nauticam MFO-1, f/16, 1/160s, ISO 1200)
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