• Ultraviolet Photography
  •  

Experiment 1: First Look at Target-UV & UV-Grey for UVIVF [See Post 7]

Fluorescence White Balance
14 replies to this topic

#1 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 23 May 2017 - 16:58

Update: 14 June 2017
Added links to other experiments.
******************************



First Look at Target-UVTM & UV-GreyTM for UVIVF

Yesterday afternoon, I received my two targets from UV Innovations: the UV-GreyTM rectangle, version 1.1 and the Target-UVTMstrip, version 1.1. The purpose of these two targets is to standardize workflow in UV-induced visible fluorescence (UVIVF) photography so that results are repeatable. The intensity of fluorescence can also be determined. This thread will host my initial experiments as I learn how to use the two targets.

Here is the link to the UV Innovations home page: http://www.uvinnovations.com/
The targets arrived with a nice foam padded plastic case and with each target also in a protective envelope. You can see everything on the website, but I'll post photos anyway. It's always good to illustrate that the website displayed items were the ones actually received.
[Disclaimer: UltravioletPhotography.com, an independent website, has no affiliation with any business. I have purchased the two targets from UV Innovations for the advertised price.]

Added: 03 June 2017
UV Innovations provides very good workflow suggestions for using the UV-GreyTM and Target-UVTM.
LINK to Workflow: http://www.uvinnovat...getting-started
While I like to fumble around reinventing the wheel when learning about
new products, please don't think you must follow my twisty path. :D


Visible Light: Front of Case
Attached Image: 750_1598pn.jpg

Visible Light: Back of Case
Or, it could be the other way around. :)
Attached Image: 750_1600pn.jpg


The UV-GreyTM rectangle, which is indeed a grey colour in ordinary visible light, is used to set in-camera white balance under UVA illumination. The UV-Grey target in visible colour is inbetween to my Labsphere targets having 20% and 50% reflectivity. However under the Nichia 365nm UV-Led, the UV-Grey target becomes a brighter fluorescent grey while the non-fluorescent Labsphere targets remain dark. One small nit I have about the UV-Grey target is its lack of wider borders for easier handling. I'm a bit worried about fingerprints from skin oils getting onto the target area. (I will ask about whether that is a legitimate worry.)

Visible Light: UV-Grey Target with Labsphere Standards
The white Labsphere area in the photo was set to 98% brightness. I tried to adjust the tones of the other Labspheres so that brightness was well distributed. Brightness and the conversion curve in a photo converter do not necessarily nor easily equate to Labsphere reflectivity.
Attached Image: 750_1607pn.jpg


The Target-UVTM, which has 4 rows of 6 patches each, is used for measuring the intensity of UV-induced visible fluorescence. In each row, three of the patches are grey. The other three are red, green and blue. All patches fluoresce under UVA illumination. The four rows increase in fluorescent intensity from low and medium on one side to high and ultra on the other.

Visible Light: Low-Medium Side of Target-UVTM
Attached Image: 750_1602pn01pn.jpg

Visible Light: High-Ultra Side of Target-UVTM
Yes, the logo is also brighter on this side.
Attached Image: 750_1603pn01pn.jpg


The recommended UV/IR blocking filters to place on the taking lens are the Wratten 2E and the Peca 918. The Wratten 2 is a pale yellow, 415nm longpass filter which blocks UV (and some visible violet, it would seem). Do remember, these pale yellow longpass filters like the Wratten 2E fluoresce yellow under UVA, so the Wratten 2E or any equivalent filter must be fitted to the rear of the lens or fitted under the Peca 918. The Peca 918 is a UV/IR blocking filter used here for its IR-blocking properties. However the Peca 918 has about a 2% leak around 700nm. So I'm not sure this would be my ideal choice for IR-blocking. We can do better with our S8612 filters, yes? If I am shooting in an entirely dark closet, the IR-blocking is not a particular worry, but I block it anyway for UVIVF work.

I was going to replicate the recommended filtration, but I have decided against that because I can do better on the IR end. And I see no need to wrestle with unmounted Wratten gel filters when I have a nice selection of mounted glass longpass filters. The important step will be to verify that my choice of filtration does block UV and IR as much as possible. http://www.ultraviol...dpost__p__16338
Andrea G. Blum
Often found hanging out with flowers & bees.

#2 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 24 May 2017 - 19:03

Next Up: Some photos of the targets under my Nichia UV-LEDs. It might be too hot to sit in the coat closet. So I'm waiting until nightfall. I'll put a blackout blanket over one of the bedroom windows and shoot in there.
Andrea G. Blum
Often found hanging out with flowers & bees.

#3 Cadmium

    Member

  • Members+G
  • 4,247 posts

Posted 28 May 2017 - 16:56

Andrea, It has been 4 days now...
How about some of this white stuff?
http://www.ebay.com/...e-/111080373214

#4 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 28 May 2017 - 19:08

My UV-Grey target had a small defect. It wasn't clear if it was a manufacturing defect or handling blemish. So I'm in the middle of the return & replacement. UV Innovations provided excellent service for this. They immediately set about creating a new UV-Grey target to send me together with a pre-paid label for returning the first one. And offered an apology for the problem.

**********

That fluorescent paint looks like FUN !!!!! Make some art.
Then make a UVIVF art photograph of the art. Meta-art. I like it.
.
.
.
.
(The 60s just called. They want their psychedelia back.<lol>)
Andrea G. Blum
Often found hanging out with flowers & bees.

#5 Cadmium

    Member

  • Members+G
  • 4,247 posts

Posted 29 May 2017 - 00:00

Art!? Ha! :-)
No, I am talking about a white material, or paint, that is white in UVIVF. Something less expensive than the uvinnovations target that you are testing.
You said it was "a tough thing to find" such a material.
http://www.ultraviol...dpost__p__16152
Yet, the targets you have has a white in UVIVF, so some such material exists.
Uvinnovations also sells UV Fluorescent paints that they have had custom made by Golden Artist Colors.
http://uvinnovations...01_archive.html
I don't see a UV Fluorescent White in their photo of paints, or at the Golden Artist Colors web site.
https://www.goldenpaints.com/
However, I wonder if there isn't some paint or material available somewhere that is less expensive than the uvinnovations target.
Thus the idea of finding some UV fluorescent paint that is white in UVIVF, maybe the same white as is used in the target.
The target is made out of something. What?

#6 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 29 May 2017 - 04:56

Well, I've been looking for about 8 years for such a target to use for UVIVF. So I'm a happy camper. :D

I hope to be able to use the target to help determine a good UVIVF WB setting for some of my cameras and pass that along everyone. Of course, if scientific repeatability and colour accuracy are wanted, then use of a calibrated target in Visible, UV or UVIVF work is mandatory. Using such targets in UV or UVIVF work also provides a nice selling point when offering UV work to museums or stock agencies.
Andrea G. Blum
Often found hanging out with flowers & bees.

#7 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 31 May 2017 - 02:29

Update: 03 June 2017
Added additional info. Corrected an error.
Acronym: UVIVF - UV-induced Visible Fluorescence
************************

First Look at UV-GreyTM and Target-UVTM

Experiment: Compare photos of the Target-UV fluorescent patches made with Auto, Daylight and Preset white balance under 365nm UV-Led illumination in the dark. [Added-->] No later in-converter white balance adjustments will be made.

Conclusion: In-camera white balance can be successfully set using the fluorescent UV-Grey target under UV-Led illumination in the dark. WOW!!!

Equipment:

Camera: Nikon D610, converted
Lens: UV-Nikkor 105/4.5
Lens Filter: Baader UV/IR-Cut + Schott GG400 Longpass (2mm)
Lighting: 365nm Nichia UV-Led Flashlight
Lighting Filter: BaaderU with Diffuser

Settings:

Neutral [0] Picture Control, no sharpening
Nikon ADL = off
f/4.5 @ ISO-400, various speeds
White Balance:
  • Daylight[0,0]
  • Auto[0,0] White Balance
  • In-camera Preset White Balance made against the UV-Grey Target under 365 UV-Led light
Description:

The experiment was conducted in darkness in my hallway coat closet. The yellow-fluorescent GG400 longpass filter was placed under the Baader UV/IR-Cut filter. The UV-Led flashlight was aimed onto the Target-UV from the top of the camera and maintained at the same distance from the Target-UV for all shots. LiveView was used to set the initial exposure time. Several shots bracketed for exposure time were then made around the initial exposure. A series was made for each of the three white balance settings.

Photo Preparation:

The files were converted to TIFs in Photo Mechanic.
No edits were applied except for cloning out one egregious lint fiber. (Where do these come from, geez??)
The white balance composite was constructed in PSE 11.
WB labels were added in PSE 11.
The composite was resized to a high-quality JPG in Photo Mechanic.

Observations:

SUCCESS: I'm very pleased to be able to set a fluorescent white balance for UVIVF photography!!! It might be useful to use this white balance preset together with a good color profile. I'll test that later.

The Usual Caveat: Converting the raw file and stuffing it into a resized JPG/sRGB box to be posted on a website may alter the colors. This is a known factor.

Daylight & Auto WB Color Cast: The purple (violet?) cast of the neutral patches under these two WB settings surprised me in its intensity. Where is this coming from? I need to investigate this, because I had thought that those two settings were useful in UVIVF.

Lens IR-Block: I did not use the recommended IR-blocker because I do not wish to deal with Wratten E gels and gel holders when excellent (better) IR-blocking can be obtained from glass filters like the S8612 or the Baader UV/IR-Cut. I'll test other IR blockers in future experiments.

Lens UV-Block: I got to wondering whether using my GG420 longpass (or the recommended 415 longpass) might cut any violet fluorescence should such a fluor happen in a subject. So I decided to use a GG400 in my initial experiment. I'll test other UV-blockers in future experiments.

Exposure: I had difficulties with deciding what was the correct exposure for the Target-UV patches. If I decreased the speed enough to really brighten the neutral patches, then the red hit the wall easily. No surprise, red is always like that. But if I increased the speed enough to keep the red completely off the wall, then the neutral patches got too dark. There is a happy medium there which can be figured out by repeated experiments. Each camera has different highlight headroom, so no universal recommendation could be made anyway. Looking at the contact sheet of photos, I decided that I liked those which were slightly darker overall because the RGB patches looked more "glowy", more fluorescent. If you over-illuminate or over-expose fluorescence, then the effect can get lost.

Framed Patches: It may not be obvious from the photos, but there is a thin covering frame over the Target-UV. I think this prevents any "bleed" from the RGB fluorescent patches onto the neutral patches. But I'm going to try some shots with the RGB patches covered to test that.

Added: 03 Jun 2017
Please note that I did NOT perform an in-converter white balance on the top and bottom strips. My purpose was to compare outcome of the two stock white balance settings -- Daylight and Auto -- to an in-camera white balance preset.

Composite Photo:
Attached Image: uvif_365uvLed_neutral0_Composite_20170530wf.jpg
Andrea G. Blum
Often found hanging out with flowers & bees.

#8 Cadmium

    Member

  • Members+G
  • 4,247 posts

Posted 31 May 2017 - 05:16

The Preset white looks pretty white to me.

#9 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 31 May 2017 - 18:32

Proposed Target-GreyTM and UV-TargetTM Experiments
  • Relate WB preset to K temps [USING various WB settings including 2500/10000 in initial tests]
  • Test other filtration on lens and on light.
  • Photograph an actual fluorescent subject. (If it ever quits raining so I can find one.)
  • Set UVIVF WB for Pentax K1, Sony A7R, and Lumix GH1.
  • Test with stock camera/lens. [DONE]

Andrea G. Blum
Often found hanging out with flowers & bees.

#10 Cadmium

    Member

  • Members+G
  • 4,247 posts

Posted 31 May 2017 - 23:40

You might want to try GG420 and GG435. Don't know, but I use GG420.
GG400 has a bit of UV just like Baader UV/IR-Cut does. So work your way up with the GG's and see if things change.
Who knows... maybe.

Also, have you tried it with a stock camera?

Edited by Cadmium, 01 June 2017 - 05:04.


#11 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 01 June 2017 - 05:32

Not yet. Just got the replacement.
But I will add that to my little experiment list above. Thanks!
Andrea G. Blum
Often found hanging out with flowers & bees.

#12 JCDowdy

    JCDowdy

  • Members
  • 1,188 posts
  • Location: Arlington, TN

Posted 01 June 2017 - 14:24

Looking good Andrea!

I am a little surprised with color cast using the Daylight WB, seems to contradict historical (film) practice if memory serves. I would like to see what other stock WB settings produce, especially incandescent (tungsten). Also are you filtering your LED?

#13 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 01 June 2017 - 15:27

I will add other WB settings to the experiment list. :D

I did have the Nichia 365 torch filtered with an old BaaderU with a diffuser. Perhaps it was not strong enough? I do have planned to try other filtration, for sure!!

While on the subject of filtering our UV torches, I wonder how best to test that? I guess Shane's Shiny Metal test is the best? I tried to test filtration by shooting directly at the torch beam, but LEDs are really really strong and can get through a lot of filtration. What gets through is more easily recorded when the LED beam is pointing directly down a lens than when it is pointed away from the lens at a subject

(I WAS WEARING UV BLOCK GOGGLES, OF COURSE, MAMA SEZ --> DO THAT!!)
Andrea G. Blum
Often found hanging out with flowers & bees.

#14 JCDowdy

    JCDowdy

  • Members
  • 1,188 posts
  • Location: Arlington, TN

Posted 01 June 2017 - 17:10

You could easily test both specular and diffuse reflection by including your 1.25" 99% Spectralon alongside your shiny metal. I bought a pin ball pinball on eBay for like $4 which is about the same diameter.

I was surprised at how much difference adding a standard RUV filter stack (U360/S8611) to the LED changed the diffuse VIS reflection on the Spectralon. If you look back at my spectroradiometric scans on that Convoy UV LED flashlight stacking comparable filters cut the relative emission at 400 nm by ~1.5 OD. I expect the BaaderU would do much the same but I did not have it at the lab the day I ran those Convoy scans.

Edited by JCDowdy, 01 June 2017 - 17:32.


#15 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 9,115 posts
  • Location: UVP Western Division, Santa Fe, New Mexico

Posted 03 June 2017 - 16:37

A few updates to Post #1 and Post #7.
Andrea G. Blum
Often found hanging out with flowers & bees.