Go for UV, with more unique diving experience

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XTAR

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You may have heard some dive resorts offer the fluorescent diving, black water diving, where night divers are given UV lights to observe see corals, critters, and enjoy the spectacular show of colors. Advanced technology allows the UV to be brought into the diving industry. So how does it work?

As there are chemical compounds contained in the tissue of the corals, some underwater creatures, it react to the UV light causing them to fluoresce in brilliant reds, purples and greens. The results can be quite amazing.

In the beginning of the UV trend, the only lights available fell in the wavelength of about 455nm, which is still within the spectrum of visible light. This light could cause the corals to fluoresce, but it could also create so much visible blue light, which sometimes diminished the impact of the glowing colors. To combat this, divers learned to use a yellow filter which cut back the excess blue, and still allow the fluorescent colors to shine through.

With technology advancing, it makes a new version of the UV LED possible, which has a wavelength just outside the spectrum of visible light at about 395nm. This LED still causes marine life to put on their fluorescent show, but since it’s nearly invisible to the naked eye, only the glowing colors are revealed. And there is no yellow filter needed! Thus, those powerful multi-color dive lights for underwater photography and video are becoming increasingly popular.
 

Bubblesong

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Fluorescence emission of critters from ultraviolet excitation is not as powerful as emission from blue wavelengths. In other words, you get better brighter fluorescence images using blue light and yellow filter than you get using UV and no filter, which is better for viewing and for photography.
I have tried both ways, and my older CREE UV excitation flashlight during Scuba is not worth the trouble. I did watch the XTAR video, and The strong fluorescence on YouTube video was not what I saw in practice with UV, but everyone is using image software, so maybe that doesn’t matter to expert photographers.
The other difference is that blue light also causes chlorophyll in algae to fluoresce red, which adds a nice color contrast.
But I would say overall, fluorescence night diving is so much fun, No matter how you get started, it is worthwhile.
 

kelemvor

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I agree with @Bubblesong having also done it both ways. Nightsea has a detailed article on UV vs Blue+filter for fluoro diving. I think this chart sums up the situation nicely:
nightsea:
coral_emission_blue_uv-300x220.jpg
Representative fluorescence emission spectra for a coral illuminated with equal energies of blue and UV light.

Why NIGHTSEA uses Blue Light for Underwater Fluorescence - NIGHTSEA


That said, if these new lights aren't too expensive then I might pick one up just to see what I could see. The blue filters are definitely a hassle. If there was enough to see with a UV light, I'd just carry it always and occasionally flip it on. In fact, it might make some very interesting photos - even during the daytime. Most cameras have a UV filter built in so you'd just capture the visible emissions caused by the UV light.

@XTAR how much are the new 395nm lights?
 

XTAR

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Thanks for your kind comment! There are purchase links for your reference:
XTAR D30 1600: 105.8US $ 30% OFF|XTAR D30 1600 Diving Flashlight CREE XHP35LED 1600lumen UV/RED/BLUE light underwater 100 Meters diving torch Diving Flashlight|LED Flashlights| - AliExpress
XTAR D30 4000: 178.2US $ 30% OFF|XTAR D30 4000 Diving Flashlight IP68 Waterproof Professional Diving Light High CRI 9 LEDS Super Bright Dive LED Flashlight UV|LED Flashlights| - AliExpress

I agree with @Bubblesong having also done it both ways. Nightsea has a detailed article on UV vs Blue+filter for fluoro diving. I think this chart sums up the situation nicely:


Why NIGHTSEA uses Blue Light for Underwater Fluorescence - NIGHTSEA


That said, if these new lights aren't too expensive then I might pick one up just to see what I could see. The blue filters are definitely a hassle. If there was enough to see with a UV light, I'd just carry it always and occasionally flip it on. In fact, it might make some very interesting photos - even during the daytime. Most cameras have a UV filter built in so you'd just capture the visible emissions caused by the UV light.

@XTAR how much are the new 395nm lights?
I agree with @Bubblesong having also done it both ways. Nightsea has a detailed article on UV vs Blue+filter for fluoro diving. I think this chart sums up the situation nicely:


Why NIGHTSEA uses Blue Light for Underwater Fluorescence - NIGHTSEA


That said, if these new lights aren't too expensive then I might pick one up just to see what I could see. The blue filters are definitely a hassle. If there was enough to see with a UV light, I'd just carry it always and occasionally flip it on. In fact, it might make some very interesting photos - even during the daytime. Most cameras have a UV filter built in so you'd just capture the visible emissions caused by the UV light.

@XTAR how much are the new 395nm lights?
 
https://www.shearwater.com/products/swift/

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