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UltravioletPhotography

Anybody have some alabaster? WB in fluor photos?


Andrea B.

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Cadmium, Thank you so much!! I am very happy to see your result. This is the first time I see a comparison with Spectralon.

 

I think - your UVIVF balance looks the same in color as in my test.

PTFE looks a little darker, - however, IF I turn up the brightness in your photo, I can see that the PTFE color is very close as in my test.

I suppose - the color is calibrated the same. Just a lighting difference, probably. I used 2 filtered convoys and very close.

 

post-242-0-08386900-1583477805.jpg

 

Your reflected UV sample looks a more violet.

But may be a difference in paper. Have you tried balance on the PTFE?

 

I will try to find the packaging from the version that I used.

Thank you so much again, you really helped!

 

[upd]

These two. №5 and №4 in the paper test. It will be the most white.

post-242-0-88293600-1583479218.jpg

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Evgeniya, I did try white balance on the PTFE 1mm, and it was very close to the Spectralon.

Do not worry that your results are different than mine. Such tests will have different results with everyone.

Your visual and reflected UV are very similar to mine. I am white balancing on the Spectralon, and my PTFE is a little bit dirty it seems, more than yours is maybe.

I was also using NX-D for all these I did here, like you.

My torches are filtered, other than that? I am using a D-610 stock with lens barrier for these, instead of the D7000 UVIR I used for the reflected UV shot.

I am using a group of 7 filtered Convoy that have the parabolic reflectors removed for no beam hot spot.

Such a group has no hot spot and doesn't require a long exposure. Powerful, soft, and no light painting required for these shots.

 

I don't know if my Canson paper is the same, but it was all they had that was water color type, and they had various sizes of that same Canson Watercolor Paper.

It is very nice paper, and very white in UVIVF.

The paper was the only white material to white balance with in the UVIVF photos.

I don't have the $800 target that Andrea has, I have ordered the UVIVF dive target however, just to try out. It is a very cute target.

 

And now what everyone has been waiting for: :tongue: (these little faces are really fun)

 

The Jet Propelled Monster Seven Nichia 365nm Whammer Jammer with SLC (Soft Light Conversion) and U-340 2mm filteration:

Visual:

post-87-0-03689700-1583483202.jpg

 

UV-only using La La U:

post-87-0-08137500-1583483196.jpg

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different

 

So your result is ✿ not different ✿ - that’s the point.

 

Your filtered light 365 nm comes from the convoy to Spectralon and is reflected almost 100%. The filter on the camera lens blocks 365, + no luminescence of Spectralon = Spectralon black. OK.

 

But PTFE is brown - so it is the color of luminescence. Right or I was wrong?

This means - that it does not reflect 100% in UV, part goes into luminescence and the color of the luminescence should be the same.

..If you have the same light, the same PTFE material, and the same material for determining white balance -

The color of any luminescence should be the same.

So this is important - that’s the whole point. There is a goal from the tests - set the balance for to determine the color of luminescence equally..

 

[upd] This cool device from convoys impresses immediately ;-)

 

[upd2] Although it seems to me Spectralon is also not completely black.

Could Spectralon have a very weak luminescence like PTFE? It can be very weak, like 1% or less, but I think it is.

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Evgeniya, The White Spectralon (SRS-99) when shot in UVIVF is also ever so slightly brown. This can't be seen in these photos, but it can be seen with the eyes.

The White Spectralon is the exact same brown color as the PTFE 1mm, except much darker, almost black.

Compared side by side using 365nm UV, there is a faint color difference between Spectralon White and Spectralon Black, the black version has no faint brown color, it is totally black.

"Brown", as Colin has pointed out in the video, is really orange, very dark orange, which could be very dark orange/red I suppose also.

However, neither the White Spectralon or the PTFE 1mm is being used for white balance in the UVIVF shots, they can't be, they are no where near white,

so instead I am using your Canson Watercolor Paper, which you recommended, because it looks very white in UVIVF.

Again, I didn't know there was any other kind of Canson Watercolor Paper, I even asked the people in the store,

so I have no idea if the paper I have is different than what you have, but this paper I have seems to work rather well as a UVIVF white balance target.

Again, using my eyes, and that is what we try to duplicate when white balancing UVIVF, we usually would want the photo to accurately look the same as how it looked to our eyes,

the Canson Watercolor Paper looks very white to my eyes when illuminated with 365nm UV.

That pertains to Andrea's original question:

"Am I understanding correctly that Canson watercolor paper is useful as both a UV-induced visible fluorescence standard as well as a reflected UV standard??"

I would say that the Canson paper I have is definitely the best UVIVF white balance target I can think of, but I either sent Andrea my white fluorescence paint or I can't find it to compare,

but regardless, the Canson Watercolor Paper is very white in UVIVF.

I would say the paper is not exactly white in reflected UV. Here is a comparison, reflected UV (La La U), white balanced from RAW using PhotoNinja, using PTFE 1mm (left) and using Spectralon (right),

there is no real difference, but this does show some slight color in the paper.

 

post-87-0-10767500-1583516898.jpg

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Steve, you beat me to it! :lol:

Good experiment.

(No, you didn't send me any white fluorescent paint.)

 

**********

Could Spectralon have a very weak luminescence like PTFE? It can be very weak, like 1% or less, but I think it is.

 

Remember when using Spectralon that it is very easy for Spectralon to reflect another object's fluorescence**. (Spectralon itself is not fluorescent.) I had a problem with my Spectralon reflecting some fluorescence from white painted bricks in an experiment a couple of years ago.

 

**********

The Jet Propelled Monster Seven Nichia 365nm Whammer Jammer with SLC (Soft Light Conversion) and U-340 2mm filtration

 

AWESOME !! :cool: :cool: :cool:

 

**********

**Spectralon is a diffuse reflector. Any incident ray is scattered in multiple directions.

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I should remind everyone that white balance alone is not always sufficient to produce accurate colours. You also need a color profile for the camera which includes the lens, filters and illumination used.

 

Added: However, I cannot figure out how you would make a color profile for UViVF.

UViVF certainly does present interesting problems to solve with respect to white balancing.

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Andrea, Correct, I didn't send you the paint, I found it today, hiding. It is SO BRIGHT WHITE! I have not compared it to the paper in a photo yet.

I think I will wait until I get the dive card, so maybe tonight, or this weekend.

 

Good point about Spectralon reflecting, but the spectralon is not reflecting anything here, I have put the white and blak next to each other, and there is a tiny bit of brown detectable in the white compared to the black,

the black is definitely more black than the white, this doesn't show up initially, you have to compare them together. They both look black if you don't compare them.

However, this is not important in UVIVF, because we can't use spectralon for UVIVF anyway. The brow also shows up if you look very close at powdered PTFE also. I have no idea what the brown comes from.

I have a small can of powdered PTFE, it is black in UVIVF, but if you compare and look close you can see hints of brow. Nothing is as black as the Spectralon Black, it is really back, more than any other black.

Again, this doesn't matter in UVIVF, what does matter is how white the paper is. It looks very white to me, but what do we compare it to really? Just to everything else I guess, and visually it looks white to my eyes.

Would be good to compare it with your tester.

My dive card is probably not as good as your tester.

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Thanks for that information, Dave.

Given cross referencing and comparing other PTFE materials in these tests, I rather doubt there is any degradation factor involved here.

 

Here are some tests that may illustrate the difference between Spectralon White and Spectralon Black in UVIVF.

Notice how Spectralon Black is completely black, and Spectralon White is not completely black.

Also notice how Spectralon White looks closest to the compressed PTFE powder, this makes sense, because Spectralon is sintered PTFE powder (compressed and heated to stick the powder together).

Also notice how the PTFE 1/4" thick sheet is similar to the PTFE 1mm.

This may be rather academic, because none of these materials would be good white balance targets for UVIVF,

even though the UVIVF version of the PTFE 1/4" thick sheet is what I used for white balance here because it rendered the photo exactly how the scene looks to my eyes.

I tried the Canson Watercolor Paper also, but decided it looked more true to life using the 1/4" sheet. However, the paper works well for WB also.

 

I should also add that of any material I have ever seen the Spectralon Black is amazingly black in UVIVF. You can put a Convoy right close to the Spectralon Black, and you will see no light on that target at all.

The black foam is the interior foam for the Spectralon wooden case, and it is amazingly black also. I think that foam would make an excellent background for UVIVF, you can shine the Convoy right close to it and nothing lights up except the dust.

 

The UV Neon White paint is is this eBay item number:121115491426

https://www.ebay.com/itm/121115491426

 

UVIVF (PTFE 1/4" Sheet used for WB)

post-87-0-44298700-1583559600.jpg

 

Visual (Spectralon White used for WB)

post-87-0-62270400-1583559593.jpg

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Yes, you can WB on the paint, however that doesn't render the scene the way it looks to my eyes, and the paper doesn't look neutral white as it does to my eyes.

Also, the paint is over exposed, so I can only white balance on it in NX-D, PhotoNinja does not let me white balance on any part of the paint.

White balancing on the paint results in a blue/green cast to the photo overall. This might be changed by adjusting the exposure,

but the exposure I am using here is to compare the other targets, the paint was thrown in as an afterthought.

 

WB on paint using NX-D:

post-87-0-83832300-1583561560.jpg

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Also, here is the difference between WB on the PTFE 1/4" sheet and WB on the Canson Watercolor Paper.

Paper works very well also, but the PTFE looks more gray to my eyes, so that WB seems to look closest to what I see.

 

WB on paper:

post-87-0-02086900-1583562473.jpg

 

WB on PTFE 1/4" thick sheet:

post-87-0-46764200-1583562500.jpg

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Andy Perrin
(Referring to the paint.) Yeah, that just looks like the white balance isn't working because of overexposure or something. (Also, we can't tell the true color for the same reason, I guess.) It sure is bright.
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It is not exactly white to my eyes, it has a hint of blue in it, The Canson Watercolor Paper looks more neutral to my eyes.

Don't worry about the paint. I don't think it is a good WB target.

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I don't have any of this GlowMania UV Neon Acrylic paint.

I would like to see, if it is possible, a proper WB on the GlowMania UV Neon Acrylic paint & a photo of a UVIVF scene, even if it is just a bunch of plastic objects, please ?

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

post-87-0-40802800-1583631778.jpg

 

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

post-87-0-90331000-1583632000.jpg

 

Twp shots using PhotoNinja copy/pasted paint WB from shot #1:

post-87-0-09365800-1583632049.jpg

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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

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