• Ultraviolet Photography

Satisfying Curiosity in Yellowstone

4 replies to this topic

#1 OlDoinyo


  • Members(+)
  • 851 posts
  • Location: North Carolina

Posted 10 October 2020 - 03:53

I have wondered--do geothermal features look like anything special outside the visible? One thinks not only of geysers, but of the hot springs with zonated bacterial mats from extremophile organisms which can coat the bottom of hot springs with concentric bands of color.

First, the matter of geysers: an eruption sequence of Old Faithful (Sony A900, Asahi 35, Baader U2, BGR:)
Attached Image: Eruption Sequence j small ex DSC00054-64.jpg

and..it looks like a geyser. Nothing very interesting here.

Perhaps we can select some frames from the height of the eruption and make a chronochromic image (RGB order, irregular intervals.)
Attached Image: Old Faithful Chronochromic j small ex DSC00057-59.jpg

That's better, if not particularly informative.

Now to the hot springs. Morning Glory Pool is famous for its rings of bacterial mats of different colors.

First, in IRG (Tiffen 12 with Pixelbender workup:)
Attached Image: MGP_IRG j small ex DSC00072.jpg

This looks colorful, but most of the color is just due to how water looks in IRG. The bacterial mats in the cooler shallows just appear faint tan as opposed to the bright yellows and oranges seen by the eye.

Now, in UV (Steinheil 50, Baader U2, BGR:)
Attached Image: MGP_UV j small ex DSC00067.jpg

This is almost devoid of color. One does see a faint gradient of hue, but to what extent this is due to the water itself is unclear. The bacterial mats do not seem to absorb UV much, which is mildly anomalous for yellow and orange surfaces.

Oh well...now we know.

#2 Stefano


  • Members(+)
  • 1,719 posts
  • Location: Italy

Posted 10 October 2020 - 04:13

I would have expected more colors in UV/IR, probably(?) it is a coincidence that those bacteria are so rainbowy exclusively under visible light.

#3 dabateman

    Da Bateman

  • Members+G
  • 2,699 posts
  • Location: Maryland

Posted 10 October 2020 - 04:32

You might need tight specific UV and IR bandpass filters.
This looks like a grant application. You could write up something and see if NSF funds you. Get some specific tight UV bandpass filters and see if there is any color difference.
The sunlight might also matter. As in how stong and what angle.
I haven't looked at bacteria in UV much. So this gives me some ideas. There are some strains that are really resistant to UV. So must reflect it or do something to avoid damage. And I mean very resistant to even 254nm UV.
Fungus will show difference as posted in some images on the forum.
I think even yeast has a slight UV pattern depending on the strain.

I still have some old food type photo ideas I need to image.

#4 Cadmium


  • Members+G
  • 4,141 posts

Posted 10 October 2020 - 04:44

Great shots. I have been there. I especially like the chronochromic (multi-temporal) shot. Very nice! :smile:

Edited by Cadmium, 10 October 2020 - 04:44.

#5 enricosavazzi


  • Members
  • 593 posts
  • Location: Borgholm, Sweden

Posted 12 October 2020 - 12:45

I got pretty much the same results with my UV attempts on Old Faithful. As far as I can see from my pictures, all bacterial and algal mats are UV-dark, regardless of their varied colors in VIS. Clean geyserite (a.k.a. sinter) is more or less featureless white in VIS, but in UV the wet and water-covered areas are dark and the dry ones chalk-white.
-- Enrico Savazzi