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Anybody have some alabaster? WB in fluor photos?

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#81 Andy Perrin

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Posted 08 March 2020 - 02:35

Yeah...as you said, not that great a WB target.

#82 colinbm

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Posted 08 March 2020 - 03:36

Thanks Steve

#83 colinbm

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Posted 08 March 2020 - 03:41

Light Bulb Moment.... :angel:....maybe
White Phosphorus, is used to make UV in mercury vapor glow white in fluorescent lights.
Could this be used to get a WB from ?
Col


#84 Andy Perrin

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Posted 08 March 2020 - 03:47

Colin, white phosphorus has a bad tendency to SPONTANEOUSLY CATCH FIRE.

Edited by Andy Perrin, 08 March 2020 - 03:49.


#85 colinbm

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Posted 08 March 2020 - 04:19

I realise that White Phosphorus is dangerous, but it is in fluorescent lamps all around us & they get broken & disposed off, with no ill effects....excepting the mercury.
Surly it could be encapsulated & used, if found suitable as a UVIVF WB ?

#86 dabateman

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Posted 08 March 2020 - 04:25

View PostDaveO, on 07 March 2020 - 23:43, said:


But you don't get two orange for that high cost. Just two bluish ones :)


#87 dabateman

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Posted 08 March 2020 - 04:28

View PostCadmium, on 08 March 2020 - 02:34, said:

The paint target is too bright to use it as a white balance all in one shot.
I had to copy the white balance from the paint exposed shot, and past it to the other shots.
Note how the white balance is not the same in NX-D and PhotoNinja. NX-D shifts the the Dive Card Yellow into white. Ninja retains the original yellow of the Dive Card Yellow, but the paper is still a little brown.
Perhaps with some other scenes you could do it all in one shot depending, but no mater how I process the paint WB it does not render the scene as seen with my eyes,
the paper (for example ) is not white, as it is in real life UVIVF to my eyes.
As I said before, the bright white fluorescent paint looks white, but to my eyes, ever so slightly blue, white balancing on it tends to shift the white paper to brown.
If I WB on the paper of the Paint exposure shot, then the paint looks slightly blue, just like my eyes see it in UVIVF.
In my opinion, in the absence of some standard agreed upon UVIVF white balance target, it comes down to how closely the WB compares to what your eyes see.
What each of our eyes see is not the same, but it might be closer to the reality than any of these targets I have tested. Let your eyes be the final judge.
To may eyes, in UVIVF, the dive target yellow looks lime green, not yellow, and the red looks orange, so my eyes see three oranges and a lime (I know...), in UVIVF.
See that here:
https://www.ultravio...dpost__p__33893
In fact, in most cases, the closest I come to what my eyes see is when white balancing in the PTFE 1/4" thick sheet or the PTFE 1mm, even though neither of those are white to my eyes or when clicked on.
This is all the time I have for this pursuit right now.

Shot #1: Paint exposure white balanced in both NX-D and PhotoNinja:
Attachment Paint_WB_NXD_and_Ninja_1280.jpg

Two shots using NX-D copy/pasted paint WB from shot #1:
Attachment Paint_WB_NXD_Pasted_1280.jpg

Twp shots using PhotoNinja copy/pasted paint WB from shot #1:
Attachment Paint_WB_Ninja_Pasted_1280.jpg

Maybe it depends on the subject. The problem with photographing an English cucumber with other salad stuff or even a kiwi fruit, is they look like the surface of the Sun next to a black object.

Do you have an English cucumber?
Try using that paint with one or a Kiwi fruit. Maybe for intense subjects it would be perfect.

Edit ok little different than I remember. Just posted my Salad that I took a while ago:
https://www.ultravio.../3762-my-salad/

Edited by dabateman, 08 March 2020 - 04:58.


#88 Stefano

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Posted 08 March 2020 - 11:55

View Postcolinbm, on 08 March 2020 - 03:41, said:

Light Bulb Moment.... :angel:....maybe
White Phosphorus, is used to make UV in mercury vapor glow white in fluorescent lights.
Could this be used to get a WB from ?
Col

Yes, but they convert the deeper lines (like 253.7 nm) too. The higher the pressure, the less "germicidal" the emission is, but they still emit UVC inside. The activation wavelength is important, the emitted color can change depending on it.