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UVIVF Possible Visible Light Leak?

Fluorescence White Balance
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#1 cdhgamer

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Posted 20 February 2019 - 05:22

Hello all!

I'm still very new to this, but I've been working on UV induced fluorescence with a Convoy S2+ 365nm Nichia Led flashlight with a Hoya U-340 2mm filter, and a UVIVF photographer I follow mentioned all my shots were coming out with quite a blue/purple cast and I definitely agree with him.
I'm curious to hear what other people think and what might be the solution for any visible leak.
If it's a matter of getting a lens filter as well, as I know a lot of people use, could you please recommend a brand and model for the lens filter?

Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm
ISO 320 / f/11 / 4 s exposure. Temp 6500 / Tint 10 - Cloudy Setting
Attached Image: DSC_3275-Edit.jpg


Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm

ISO 400 / f/16 / 2 s exposure. Temp 7500 / Tint 10 - Shade Setting

Attached Image: DSC_3283.jpg


Spoon Test



Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm

ISO 500 / f/16 / 4 s exposure. Temp 5500 / Tint 10 - Daylight Setting

Attached Image: DSC_3359.jpg


Edited by cdhgamer, 20 February 2019 - 05:24.


#2 Cadmium

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Posted 20 February 2019 - 07:23

Things to keep in mind:

1) If you are using U-340 2mm with Nichia 365nm LED, then there is no visual or IR light emitted. No violet or blue.
2) If your stock or full spectrum camera can see UV, then you need to filter the lens, with some kind of barrier filter that cuts just above 400nm.
The combination of #1 and #2 will keep any violet/blue leak from the LED out of the scene, and also keep any reflected UV from the scene from being seen by the camera.

Almost everything fluoresces, and violet/blue is quite common fluorescence from many object, paper, dust, even some black objects will fluoresce some small amount of blue,
in fact, it is a little hard to find things that don't emit some small amount of fluorescence. Be aware of that to start with.
What you are seeing is not visible violet blue, but it is in fact fluorescence.
Want to test that? You have eye protection that you totally trust will block all UV? If so, and be very careful to be sure of that first,
put those glasses or goggles on, go to a mirror, and flash the light at the mirror, very shortly, just to be safe, and you will see blue in the mirror from the torch lens with no U-340 on the torch,
but with the U-340 on the torch, it will look black.
You will of course still see dust and all sorts of other things fluorescing violet blue in varying brightness's, but that is not reflected violet blue from the torch, it is fluorescing violet blue.

3) Now, there is this little thing called white balance, and that will also change what your photo looks like.
So there is that...

But I think the mirror test will prove the point. Just be very sure you are using eye predilection that totally blocks UV -400nm.

Edited by Cadmium, 20 February 2019 - 08:11.


#3 cdhgamer

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Posted 20 February 2019 - 08:11

View PostCadmium, on 20 February 2019 - 07:23, said:

If you are using U-340 2mm with Nichia 365nm LED, then there is no visual or IR light emitted. None at all.
Explain the spoon test please.

In the sticky for UV Induced Visible Fluorescence, there's a part on the "Shiny Metal Test in UVIVF Photography", although reading back on it again, I see that the hurdle to pass is for the metal to not have a shiny reflection, which it passed.

Do the flower photos seem to have an unusually strong blue or purple cast though?

#4 Cadmium

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Posted 20 February 2019 - 08:24

I don't know about the spoon test for fluorescence, and I don't know what I am looking for in that test. I thought the spoon test was used for reflected UV.
I am the wrong person to say anything about the spoon test, I have never used it.

I have no idea how that flower should look in fluorescence.
I would play around with the white balance in post from RAW and see if you can get it to look like what you see with your eyes. A little hard to do, to remember what you saw with your eyes...
but that is what I shoot for personally.
There are special white balance card/targets for fluorescence, but they get kind of spendy. Andrea has one, and has posted about that... let me see if I can find that.
Search for "Target-UV" (in quotes).

Andrea's original post.
http://www.ultraviol...__fromsearch__1

And ask others how they white balance UVIVF also.

Edited by Cadmium, 21 February 2019 - 01:36.


#5 cdhgamer

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Posted 20 February 2019 - 08:33

View PostCadmium, on 20 February 2019 - 08:24, said:

I don't know about the spoon test for fluorescence, and I don't know what I am looking for in that test. I thought the spoon test was used for reflected UV.
I am the wrong person to say anything about the spoon test, I have never used it.

I have no idea how that flower should look in fluorescence.
I would play around with the white balance in post from RAW and see if you can get it to look like what you see with your eyes. A little hard to do, to remember what you saw with your eyes...
but that is what I shoot for personally.
There are special white balance card/targets for fluorescence, but they get kind of spendy. Our High Princess Andrea has one, and has posted about that... let me see if I can find that.
Search for "Target-UV" (in quotes).

Andrea's original post.
http://www.ultraviol...__fromsearch__1

And ask others how they white balance UVIVF also.

Thank you Steve. The fellow that was trying to help me out took a look at my RAW too and he wasn't sure how my same daisy was so monochrome compared to his, hence all this confusion. I'll attach his photo below if a Flickr link will work. Also, is there any difference between the

Uvex Ultra-Spec 2000 Safety Glasses colors? I have the orange pair but that obviously is a problem for getting a good idea of the colors I saw. I'm just curious if the clear safety glasses have the same UV safety protection.



https://www.flickr.c...in/photostream/

#6 Cadmium

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Posted 20 February 2019 - 08:44

The orange ones actually leak a bit of high UV per my tests, strange, but... but they should work fine for a flash tests in the mirror I think, with a Convoy anyway.
I use the amber ones myself, for that reason, the amber ones block more of the UV (per my tests) and more than enough of the visual range for me.
There are some clear goggles that will block all the UV, but I can't say exactly which do that.
I have a pair of UVEX clear that do that I think.
I am quite confident of the Amber ones. Happy with those, they easily go on over my reading glasses too.

Edited by Cadmium, 20 February 2019 - 08:46.


#7 Cadmium

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Posted 20 February 2019 - 08:57

I just went and did it myself, Convoy S2+ Nichia 365nm UV LED, U-340 2mm filter, UVEX Amber glasses... totally dark bathroom mirror,
flashed the torch at the mirror... all I see is dust., Dust on the torch filter, dust on the mirror, etc..
The U-340 2mm, passes no visible, no visible range violet or blue, nothing visible.
Be very careful with that crazy test people! OK.

Edited by Cadmium, 20 February 2019 - 12:22.


#8 dabateman

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Posted 20 February 2019 - 14:47

I don't think you have any visible light leak. The image actually looks like you caught some of the 380nm to 400nm reflective light off the flower. Thus looking a little monochromatic. I know my stock Nikon Df can see in this region and would assume the D810 to be similar. So you may want to add a 2E, or Lp455 to your camera lens if you don't want to capture the UV reflective light.
I don't know about the Sony camera or lens your friend is using. Is he also using a filtered convoy? As his image to me looks like he is getting vis leakage to help excite his flower. Zwb2 filtered convoys can leak some 405nm light.
I actually like the excitation from 405nm, sometimes called cyan excitation. It can also be more intense for some flowers than 365nm coming from the convoy.
Thus I use 405nm light bulbs to get that.

#9 Andy Perrin

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Posted 20 February 2019 - 16:40

If you are not filtering the camera, you may want to add a UVIR-cut filter (Baader UVIR-cut for example). I will say that an awful lot of things really do fluoresce blue, though!

#10 dabateman

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Posted 21 February 2019 - 02:05

Cadmium,
In your post 7 you deleted all the fun CSI jokes. Since I once applied to the FBI, I did find them quite funny.

@cdhgamer, looking back at your exposure time of 4 seconds, compared to your friends 30 seconds. I am fairly sure that you have caught reflective UV. Unless that is meant to be 1/30 seconds, for your friend. Then for sure he has 405nm light exciting his flower. Your ISO values are also 2 stops apart.
Do you know any specific details about his set up? Source of light and if any filters were used? Either on the camera or on his light source?

#11 cdhgamer

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Posted 21 February 2019 - 05:48

Hey all, so Craig sent me a RAW shot looking down the barrel of his Convoy S2+ 365nm Nichia LED, the same flashlight, but with a 1.5mm UG11 filter on it, and I took a shot of mine with the 2mm U-340 filter. He does use a Hoya UV filter of some sort on his lens, I'm double checking which one, but I'm assuming that's the difference in not getting such a blue cast to his shot/cutting the reflective light?



Sony A77 / Tamron 90 mm Macro / Hoya UV filter on the lens
Convoy S2+ 365nm Nichia LED / 1.5mm UG11 filter on the Convoy
ISO 1600 / f/5 / 1/40s exposure
Daylight Setting - 5500/10 with no edits

Attached Image: CraigRaw.jpg


Nikon D810 / Tokina 100 mm Macro
Convoy S2+ 365nm Nichia LED / 2mm U-340 filter
ISO 800 / f/5.3 / 1/6s exposure
Daylight Setting - 5500/10 with no edits

Attached Image: Todd Raw.jpg

Edited by cdhgamer, 21 February 2019 - 05:59.


#12 Cadmium

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Posted 21 February 2019 - 06:51

OK,
1) There are a lot (OK a few) people selling that they SAY is UG11, and that goes for just about everything else, but some of what is said to be whatever is not actually whatever. Some of what is said to be UG11 or U-340 is just Chinese ZWB1.
2) Real UG11 and U-340 will work the same for Nichia LED visual violet/blue suppression. Just use the U-340 because it is half the price, and at 2mm thick it works the same.
3) Oh yeah, almost forgot, 1.5mm UG11/U-340 is not thick enough to block violet/blue below 400nm, your friend needs thicker glass.

In a while, I will used two new batteries and show a test of two torches at the same time, one will be filtered and black showing dust, and the other will be unfiltered and will show violet/blue light.
Buy your tickets now...

Edited by Cadmium, 21 February 2019 - 06:52.


#13 cdhgamer

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Posted 21 February 2019 - 07:06

I'll buy my ticket for the show, haha, in the mean time, I'm going to try to search out any other dark rooms in my house to double check for possible light pollution in any rooms that might be interfering

#14 Cadmium

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Posted 21 February 2019 - 08:01

Well I am very glad you are here, these turned out pretty good.
OK, hold on... have to resize them.

Edited by Cadmium, 21 February 2019 - 21:45.


#15 Cadmium

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Posted 21 February 2019 - 08:33

Wow, lost the entire audience... :-(
I didn't white balance these, someone else can if they wish.
These were shot with a stock D610, and an old 18-55mm VR (which reduced the crop on the full frame D610 sensor, but that is ok, the lens filter thread was 52mm, to match the lens barrier filter I used,
which was a Firecrest 52mm UV IR MC, which I rather like for visual range with good 400nm UV blocking, I have not rigorously tested that filter yet, but it feels good to me, and I think I like it better than
the Baader UV/IR-Cut filter for cutting UV at 400nm.
It is just a better Visual only range filter than Badder UV/IR-Cut if you ask me, but that would be my non compared preliminarily assessment of that filter. You can get them in convenient sizes even, so...
But the lens barrier filter is not the point here.

The PIONT here is does U-340 2mm block visual violet/blue and all visual range emission from the Convoy/Nichia torch. Yes, it does.

Here are two Convoy S2+ Nichia 365nm UV LED torches.
Both with fresh fully charges batteries.
The torch on the left has no filter, just the original clear glass on the front.
The torch on the right has the original clear glass removed, and replaced with a Hoya U-340 2mm thick filter on the front.
No white balance, absolutely no post processing, other than resized to 1280 wide.
White balance IS important, and will change the results of UVIVF, but in this case, I didn't see need to fuss with that.

I have sorted these examples from top to bottom, the ones I like the best at top, but they all illustrate the same thing, with slightly various aspects of the same thing.

I was going to say a few things more, but I think those pics speak for them selves.
The white material is a PEC pad.
The brown material is brown corrugated box cardboard.
You see how both of these materials fluoresce. Everything pretty much does. It is hard to find something black enough that will not fluoresce some.
I hope you enjoy the show. ;-)

Attached Image: Convoy_NoFilter_vs_U340Filter_C_1280w.jpg

Attached Image: Convoy_NoFilter_vs_U340Filter_A_1280w.jpg

Attached Image: Convoy_NoFilter_vs_U340Filter_B_1280w.jpg

Edited by Cadmium, 21 February 2019 - 18:55.


#16 Cadmium

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Posted 21 February 2019 - 08:47

A lot of things out there these days are not what they say they are. Fake stuff.

Attached Image: U340_2mm_Vs_UG11_1p5mm_and_UG11_2mm_Dia_Lin.jpg

Edited by Cadmium, 21 February 2019 - 09:49.


#17 Andy Perrin

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Posted 21 February 2019 - 15:48

I would never white balance your photos, Cadmium, you are the expert on them.
--
Re the Firecrest 52mm UV IR MC: why that filter, versus the Firecrest 52mm UV 400nm (which claims additional UV protection)? I was about to go buy one when I noticed they had several versions:
https://www.amazon.c...sr=8-1-fkmrnull

#18 Cadmium

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Posted 21 February 2019 - 18:56

You could use either one for this.

#19 cdhgamer

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Posted 22 February 2019 - 05:35

Thanks so much for the science behind that all Steve! Maybe I've just been unlucky on my flower choices

#20 UlfW

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Posted 22 February 2019 - 09:57

View PostCadmium, on 21 February 2019 - 18:56, said:

You could use either one for this.
Is that really correct?

The UV IR MC cut at 370nm or 400nm according to their website:
https://www.formatt-...ch.com/learn-uv


The Convoy LED torches has a maximum intensity rather close to 370nm

Wouldn't the 370nm version give an UV contamination from the torch with an U-360, 2mm.
The transmission of U-360 is 50% at 370nm.

Edited by UlfW, 22 February 2019 - 11:04.

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