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Fire Dive Gear - underwater fluorescence photography equipment

Fluorescence
50 replies to this topic

#41 Cadmium

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Posted 11 March 2020 - 14:41

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.

Edited by Cadmium, 11 March 2020 - 14:55.


#42 Stefano

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Posted 11 March 2020 - 18:29

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.

Edited by Stefano, 11 March 2020 - 18:32.


#43 Andrea B.

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Posted 11 March 2020 - 22:50

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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#44 Øivind Tøien

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Posted 12 March 2020 - 01:32

Along the same lines, fluorescent amphibians - not sure if anyone pointed to this one here before (using blue and ultraviolet light for excitation):

https://www.nature.c...598-020-59528-9

Science news article about it:
https://www.sciencem...der-right-light
Øivind

#45 colinbm

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Posted 12 March 2020 - 02:06

Humans fluoresce bright red after being absorbing UVA for a couple of hours.... :excl:

Edited by colinbm, 12 March 2020 - 02:13.


#46 Stefano

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Posted 12 March 2020 - 02:07

View Postcolinbm, on 12 March 2020 - 02:06, said:

Humans fluoresce bright red after being absorbong UVA for a couple of hours....
Is UVA energetic enough to do that?

#47 colinbm

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Posted 12 March 2020 - 02:14

View PostStefano, on 12 March 2020 - 02:07, said:

Is UVA energetic enough to do that?
Thousands of people do it every summer at the beach.....

#48 Stefano

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Posted 12 March 2020 - 02:17

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.

#49 colinbm

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Posted 20 March 2020 - 07:24

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.

#50 Cadmium

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Posted 20 March 2020 - 20:37

It fluoresces with the Convoy S2+ 365nm UV Nichia torch just fine for me,
https://www.ultravio...dpost__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,.

#51 colinbm

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Posted 21 March 2020 - 13:57

You are correct in darkness Steve, I just tried the two lights, 365nm & 450nm & in a dark room they both fluoresce is shown on the Fire Dive Gear.
But in a filtered daylight room the 450nm light works very well.