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Fire Dive Gear - underwater fluorescence photography equipment


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Andy Perrin

What fluorescence do you want?

For induced IR fluorescence, a 450nm peak light is great. I like using 405nm LED or BG39 filtered white LED.

Mark had some great photos with a cyan, approximately 488nm light source.

The Visible induced fluorescence looks best under 365nm. But saying that I haven't played with a 385nm LED and that might be better/different/worst. Don't know. I may add that light to my 365nm and 405nm leds.

Amazon does have cheap 385nm E27/E26 bulbs.

What I'm really asking is what is your basis for saying things like "the visible fluorescence looks best under 365"? Has anyone tested this systematically for a variety of species under a variety of excitation wavelengths and tabulated something like overall brightness?

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I also don't think I was clear.

If we assume visible light is 400nm to 700nm. Then what are you looking for? Blue is roughly 400nm to 500nm. So you can't use a 455 or 488nm light source to get blue fluorescence, unless you have a tight cut filter.

Look at my salad series. There was blue and red and little green depending on the vegetable.

This is why I said I like 365nm. I have a 405bp10 filter, which I have imaged with my 405nm light source, and didn't like the visible fluorescence for the one subject I tested.

I haven't tested a 385nm led light, but with a U340 filter, that might produce an excellent fluorescence range into the visible.

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Andy Perrin

Sure, but you could test systematically from 300nm excitation down to 400nm and tabulate overall brightness of the fluorescence. The point is to be systematic and not haphazard. You make a little table:

 

Species name

excitation wavelength | brightness (400-700nm)

300 nm | ???

320 nm | ???

...

 

like that for a bunch of species. Then you compare the results.

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How do you define which one looks best? Since colors change depending on the exitation wavelength, there isn't a "right" wavelength, but since 365 nm is a standard, well-known UVA wavelength, it can be used as the wavelength of reference for UVIVF. (I couldn't avoid writing "wavelength" so much).
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Andy Perrin
I was using "brightness" as the measure, not some kind of image quality, Stefano. I don't know how you would quantify "best" either.
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Probably deep UV is absorbed more and you have less fluorescence there... but someone needs to test it.

 

Nope I need food. I don't need this test.

I think we should just switch over to using Colin's new 365/375/385/395nm led quad head and hit with all the good UV-A wavelengths. Filter that with a U340 and your all set.

 

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Andy Perrin
Heh, I guess just hitting it with every damn UV wavelength would probably be best. Then you get everything, right?
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Heh, I guess just hitting it with every damn UV wavelength would probably be best. Then you get everything, right?

Yes, you should. Things can only add up, not subtract.
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This dive card, and the guy that makes it, and my conversations with him, quite frankly have challenged my basic foundation for my long time assumption that 365nm was THE band to use for fluorescence.

Prior to that I just thought any old 'black light', which usually has a much wider band reaching down to 320nm and up into the visual range (not sure how far up).

But after spending time here, for years, a decade or so, I have come to believe and advise narrow 365nm as being THE optimal excitation for UVIVF.

Now suddenly I am asking why. Where did I get that? I got it here. Then why do we say that? Where did that come from?

That certainly is NOT the band that marine biologists use. They don't use UV at all, they optimally use 455nm, with barrier filters that go with that.

Here: As to using UV vs. 455nm, the marine research community has gotten away from UV a couple decades ago because it is very inefficient, provides poor results and is very harmful to the eyes of the creatures (that have eyes) causing - in most cases, permanent blindness.

Perhaps the inefficiency is simply due to the water filtering out much of the UV/violet, and that would then make scence given the narrow 365nm, but I don't know that is the reason exactly or entirely.

Certainly causing damage to life is not good.

The things is, it would behoove us to pin down exactly the reason for what we think, and the reasons for what the Marine community thinks and uses, the exact reason for each thinking,

because we want to be all inclusive here and I think we want to understand both situations so we can expand our thinking and advise those who are doing things different than we are.

This is something we need to figure out.

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Because different things are excited to fluoresence at different wavelengths.

OK you have found that the dive industry like to use 455nm.

Mineralogists use shortwave, midwave & longwave UV to excite minerals.

Then there is the cyan 500nm induced IR fluorescence.

The only optimum is what has been before & researched.

Biologist seem to like to get the nice blue/cyan into the picture too....?

What floats your boat I guess...?

Yeah it would be a long list.

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I think that 365 nm is a standard, and if you want to standardize results, you should use this wavelength. Of course, the more wavelengths you use, the more information you have, the better. There is no point in asking what is the correct wavelength, all are equally valid. It is like asking if 360 nm UV should be rendered as yellow and 390 nm as blue-violet, or if LWIR must be rendered white-hot, rainbow, iron or with other color palettes (Andy and I had a discussion about this here https://www.ultravio...__fromsearch__1). It is a very complicated thing to handle.
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Steve, strangely enough I've been thinking about the question of fluorescence recently. The skin research world uses UVA induced fluorescence a lot to look at skin dryness, and also bacterial presence, and melanin formation and distribution. Dermatologists used to use Woods lamps with 365nm fluorescent tubes for this, but there is a move now to more use of LEDs. One of the manufacturers of skin research equipment, has recently moved from a small fluorescent tube to LEDs, and have shifted their wavelength from 365nmish up to about 385nm.

 

Then at the other end of the scale is the use of 295nm light sources, to look for fluorescence at 340nm - UV induced UV fluorescence. Obviously under very controlled exposure.

 

There is also one manufacturer of equipment that uses a Cyan light source, to look for fluorescence in the green and orange regions.

 

It really is 'horses for courses' as they say.

 

I do agree though with something you said, that we should not be causing damage to creatures that we are imaging (if we are imaging creatures).

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I didn't say that myself, it was a quote from part of the Dive Card guy Lynn's email.
I do agree with that also of course.
We know that UV is dangerous to our eyes and other living eyes.
My reason in posting the quote is because, and let me post it again because this is important to get into our heads here,
"the marine research community has gotten away from UV a couple decades ago because it is very inefficient, provides poor results".
So UV doesn't work for them, it isn't as efficient as the 455nm light. I think you can compare the difference in the results in some of those links.
I am not saying we should use 455nm, however, when someone comes here asking about UVIVF underwater (say), which is obscure, but someone has been on here doing some of that,
we should not say that 365nm is what they should use, we should tell them about 455nm because that is the marine standard.
Again, I am not sure exactly why yet, I have not had more time to talk to him, but I am guessing just because the blue light is stronger and transmits best through water, not that the light has to travel far,
but the blue light is much stronger underwater than UV.
However, I am not clear on the reasons yet.
Also, I don't' see a blue fluorescence in the 455nm fluorescence shots I have seen them show, so there is that also. Makes sense.
I don't think anyone here is doing underwater UVIVF or else someone would have known all this and talked about it.
I understand there are many NM points that could be used in the spectrum to fluoresce things, I have used green light for example for IR fluorescence,
but why have we decided 365nm is the best? I suppose just because it is below visible blue.
Who decided that, where did that come from, where was that established,
and shouldn't we know about the standard 455nm for underwater UVIVF? We don't, because we don't do that.
I would not have known anything about this unless I got that dive card that this topic is about.
However, up until a day ago, if someone asked me, "what nm light should I use for underwater UVIVF?" I would say 356nm.
I would not tell them that now.
And I guess we know a little more about the dive card, and that it isn't likely anyone here would be interested in, UNLESS someone was doing underwater UVIVF specifically using 455nm light,
because that is specifically what the dive card is designed for.
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We are all learning something here, that's a very good thing. 365 nm, being a standard (as I said above) and being pretty much invisible when filtered, became what we all use. It is a versatile wavelength, as you can remove all UV from a U-340 filtered Convoy by placing a GG420 or maybe even a GG400 on your camera lens. This wavelength was already well know before 365 nm LEDs, because of the mercury I-line (365.4 nm) and because of the fact that, according to Wikipedia, Wood's glass peaks at 365 nm. What if we had efficient 360 nm LEDs? Yes, that's a 5 nm difference, but would have they become our standard? Probably yes.
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Now suddenly I am asking why. Where did I get that? I got it here. Then why do we say that? Where did that come from?

 

Nobody *here* has ever said that 365 nm UV-Led was the "best" visible fluorescence inducing wavelength to use. For a number of years, we could only get 365 nm UV-LEDs to use. Then I was able to get a 380 nm UV-LED made a few years ago. And gradually other UV-LED wavelengths have become available, although not widely available.


 

I think that 365 nm is a standard, and if you want to standardize results, you should use this wavelength.

 

No, there is no "standard" for fluorescence.


 

I'll repeat: 365 nm UV-LEDs were the only thing we* could get to induce fluorescence except for the very dangerous 254 nm sanitizing wands. So that is why you see it used here so much. And we tend to use wideband filters for fluorescence photos because, again, that's all we have (or had). Now narrowband filters are more available, although rather expensive.

 

If you were making scientific fluorescence experiments, both your inducing illumination and your recording lens would be covered by very narrowband filters.


 

*Same goes for the fluorescent rocks people. All they had available was 365 nm and 254 nm. So most fluorescent rock pages on the internet still refer to only longwave/shortwave results from 365/254 nm. There are undoubtedly rocks which fluoresce under other inducing wavelengths.

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I know that UVB does that, maybe also light lower than 340-330 nm. There isn't a lot of UVB in sunshine, but enough to paint you red.
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  • 2 weeks later...
I have the Fire Dive Gear, Fluorescent Test Slate, & I made up a 450nm LED & the slate fluoresces nicely, but not with the 365nm Convoy.
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It fluoresces with the Convoy S2+ 365nm UV Nichia torch just fine for me,

https://www.ultravioletphotography.com/content/index.php/topic/3753-fire-dive-gear-underwater-fluorescence-photography-equipment/page__view__findpost__p__33893

however some of the colors will look different with 455nm narrow band light.

Specifically, as it was explained to me the filter they use for their 455nm light is:

Zero amplitude at 445nm to 465nm at zero amplitude. At the full width half max (FWHM) of 455nm it’s less than 10nm wide.

That all being said, let me repeat, the Dive Card absolutely does fluoresce quite strongly with a 365nm Convoy S2+ torch,.

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