• Ultraviolet Photography
  •  

Filter reality check: UV "Real estate photography"

Filters
5 replies to this topic

#1 Dan Kuespert

    Member

  • Members
  • 7 posts
  • Location: Baltimore, MD

Posted 04 March 2019 - 09:49

I'm setting up to do some unusual (weird?) work, photographing laboratories under UV (reflectance and induced fluorescence) to look for chemical contamination (things like spills that weren't cleaned up right, etc.); in a way, it's got elements of forensic and real estate/interior design photography, hence the title.

After some offline discussion with Cadmium, I came to a preliminary selection of filters, and he suggested getting some community input. Any suggestions or refinements to the below are welcome, as are statements that I'm a complete moron to be trying this :) .

I'm doing photography of entire rooms and sometimes details thereof. Some of the labs have windows, and even if I work at night, there's still streetlights, etc. to contend with. Camera is a modified full-spectrum Nikon Z6 with a Nikon Ai-S 50mm f/1.8 Series E lens (which, according to the lens sticky, is UV-capable). Reflectance photography should be possible night or day, but induced fluorescence will be dependent on getting it dark enough.

I plan to illuminate mainly with a 400J xenon flash, filtered with one of Cadmium's La La U filters to isolate the UV wavelengths. I do have two other UV sources, a 365nm flashlight and a 395nm flashlight, each of which will have a stack of U-340 and S8612 glass, 2mm each. The flashlights will be used for spot illumination and possibly for some experiments in light painting.

For the reflectance work, I plan to place another of the La La U filters on the camera (because I don't have total control over stray light), and for the induced fluorescence, the camera will receive a Baader UVIR cut filter.

If someone would help me out by blowing the appropriate holes in the above (and hopefully helping me fill them in), I'd be greatly appreciative.
============================
Daniel R. Kuespert, Ph.D, CSP
dankuespert@me.com

#2 Mark

    Member

  • Members(+)
  • 538 posts
  • Location: Massachusetts, USA

Posted 04 March 2019 - 23:09

Hi Dan,

I'm not so inclined to blow holes in anyone's good work. Instead I'd just like to offer the following, regarding your intent to capture UV induced fluorescence.

Per your description of the visible-light contaminated scenes, even at night, I wouldn't worry about this so much. Yes, do try to minimize ambient VIS which will blend with, and potentially overpower your induced fluorescences. But perhaps be open to some small amount of VIS, as it can actually serve to provide valuable context to what could otherwise look like just a bunch of glowing spots (if photographed as 'purely' UVIVF).

I've struggled with this in my own images, and it is often still a mental challenge for me to allow VIS "contamination" into my fluorescence images. But a small amount does seem to go a long way in making an otherwise 'weird' image make sense.

Just my opinion of course. Hope it helps in some way.

P.S. I've done exactly this kind of imaging, in several labs... and even expecting something to jump out at me, it's still amazing what I found (as I guess you could be equally surprised as well).

#3 dabateman

    Da Bateman

  • Members(+)
  • 1,318 posts
  • Location: Maryland

Posted 06 March 2019 - 04:17

You may want to read up on Luminol. There are interesting things to see and the forensics world has worked with this. Also post this in the forensics section of the site. You will get better answers I would guess. PM Andrea to move the thread or post a new topic.
I remember bleach, sodium hypochlorite has an interesting effect. You may also just want to grab a buch of different chemicals on test strips an image them controlled. Similar to what Cadmium (Steve), has done with powders.

Edited by dabateman, 06 March 2019 - 04:19.


#4 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 7,541 posts
  • Location: USA

Posted 15 March 2019 - 16:45

a 400J xenon flash, filtered with La La U
a 365nm flashlight and a 395nm flashlight, each of which will have a stack of U-340 and S8612 glass, 2mm each.

Looks like you have the UV illumination well covered. Good! Note that the 365nm or 395nm flashlights as a single source of UV illumination tend to produce a monochrome effect because they are peaked around a specific wavelength. But the 365nm will be extremely useful for focusing prior to shooting with the Xenon flash.
*****

For the reflectance work, I plan to place another of the La La U filters on the camera

Yes, this is necessary (mandatory). The flash may output some Visible or IR even with filtration because Xenon flashes are quite strong. And during the day windows may transmit Vis/IR as well.
*****

for the induced fluorescence, the camera will receive a Baader UVIR cut filter

Yes, this will provide "good enough" results for UV-induced visible fluorescence shot in the dark. Mark has given good advice on this topic. I note that it is extremely difficult to attain "perfection" in fluoresence work without using narrowband filtration. Should anything arise in your eventual results that might need further elucidation, then you can order special narrowband filtration to trap it.

If the laboratory rooms do not have window blinds to close against streetlights, perhaps you can hang some tarps to block some of it?

I encourage you to make some test UVIVF shots prior to the actual work. Make a fluor photo in total complete darkness. Then make the same photo with a lamp on in another room so that some stray Vis light "contaminates" your photo. Note the differences between the two photos to see how easily a fluor photo can get washed out. I'm trying to think what is a good subject for this -- flower pollen, olive oil in a glass, quinine water. Take any of those into a dark closet and make UVIVF shots. Then open the door for Vis contamination from that lamp.

(I know, I know.....we goofy fluor photographers are always making tests in dark closets..... :D :D :D )
Andrea G. Blum
Often found hanging out with flowers & bees.

#5 Andrea B.

    Desert Dancer

  • Owner-Administrator
  • 7,541 posts
  • Location: USA

Posted 15 March 2019 - 16:48

P.S. Never do the following: Spend a couple of hours cleaning up your home bathroom until you believe it *truly* is sparkling clean, then that night shine your 365nm UV-LED torch/flashlight around it to see just how much you've missed.
Sigh. :rolleyes: :wacko:
Andrea G. Blum
Often found hanging out with flowers & bees.

#6 Andy Perrin

    Member

  • Members(+)
  • 2,689 posts
  • Location: United States

Posted 15 March 2019 - 17:49

Andrea, I did my mom’s sparkly clean kitchen. She refused to look at the resulting photo. :-)