Dive light from E-Bay -- Great buy!!!

[TT_Vert]

If you're into night diving you may want to pick up one of the UV model lights as well. Same light just a 395 uv blue led chip. Nothing quite like coral fluorescence.

Can you tell me where you found this in a UV model? I'm having a bit of a hard time finding it.

Dave

 

[stuartv]

I just got one of these lights (from the OP) for $22 off eBay.

I also got an Xtar D26. I compared them both to one of my DGX 600 lights that I have been using for a while.

I started another thread, with pictures:

Review: DGX 600 vs Xtar D26 vs $22 eBay light

Just FYI.

My conclusion, the DGX 600 and the Xtar D26 are both worth the little bit of extra money (to me).

 

[TT_Vert]

Has anyone else used a spectroscope on these UV lights to see their wavelength? I purchased one of these and put it into one of these. Measuring the wavelength with a cheapy spectroscope there is light from 400nm up to 675nm. Am I to assume then that to product the purple color it is using the entire spectrum of light and it is not UV?

Thanks

Dave

 

[dberry]

I'm not sure what you mean by a "cheapy spectroscope", but it's possible your spectrometer is mainly sensitive to the visible region (e.g. >400nm). Your light could be putting out 90% of it's energy in the UV, but you'd only be measuring the tail that reaches into the visible.

It's not necessary to use "the entire spectrum" to produce the purple color you see. UV stands for "Ultra-violet" - as in UV light is beyond the visible light we typically call "violet". LEDs aren't monochromatic (like a laser) - even a true UV LED produces some wavelengths spilling over into the visible (and appears violet aka purple.) Just remember that real UV light isn't visible - that is humans can't really see it (even though it's burning your skin and retinas The purple seen with "black lights" is just the spill over into the visible. It's the invisible UV rays that make things like black light paint (and cat pee) glow in the visible.

OTOH, there are different "UV" LEDs that have maximum output at different wavelengths, and some "UV" dive lights are intentionally more in the (visible) blue. Most corals fluoresce more brightly under blue light (but this is best observed if you have a yellow filter on your mask and camera.) Try googling "blue light fluorescent corals" or look here:

Coral fluorescence vs excitation wavelength - NIGHTSEA

 

[TT_Vert]

I got one from amazon for under $10. I do know that UV is invisible to the naked eye and just assumed that a true UV light would only put out light <400NM. I'm worried about that visible light that is spilling over just saturating the coral and counteracting the fluorescence of the coral. Yeah I'm aware of using a blue light w/ a yellow filter but I've got enough gear to carry to add a yellow mask filter.

Dave

 

[CuzzA]

Can you tell me where you found this in a UV model? I'm having a bit of a hard time finding it.

Dave

Dave I'm sorry for the late reply.

This is the one I bought. UV 395nm 3x XPE LED Underwater 100M Scuba Diving Flashlight Torch+18650+Charger

I haven't used it while diving in a location with a lot of coral flourescents yet, Gulf coast of Florida doesn't have the amazing corals one would find in say the Great Barrier Reef or Indonesia, but I can confirm from using it on my reef tank (Which does have aqua cultured Aussie and Indonesian corals) that it does a fantastic job at illuminating and exciting coral fluorescent proteins.

Btw, I had confidence in this purchase because it's the same led chip used for reef tank aquarium lightning. So I knew what to expect.

 

[TT_Vert]

No problem thanks for the update. When you illuminate from the top w/ this light do you see a column of light in the water or just the coral illuminated?

Dave

 

[CuzzA]

I didn't notice an illumination of the water column. Certainly not as bad as my white light. If there's a lot of particulate matter in the water I would expect there will be some blue/purple light reflected.

Here's one of the first videos I did. It's pretty crappy as I was using a single pistol grip GoPro camera rig. My white lights were also not video lights. I've since redone my setup.

This video was shot during the day in the gulf. I believe around 5:49 I really start using the uv light.

Here's another night time pool test on some toys with my new rig. The video is a little shaky because I was just dragging around my pony bottle on the bottom of the pool so I had to use one hand most of the time.

 

[TT_Vert]

Thanks, mine definitely shows a whitish column of light while shining from the surface down into my fish tank.

Dave

 

[bkilleen]

Just pulled the trigger on one of these cheapy eBay lights (and battery/charger).

Now just playing the waiting game until it ships. Fingers crossed for positive results!