• Ultraviolet Photography
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Thistle

Fluorescence
11 replies to this topic

#1 Nite

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Posted 24 November 2020 - 11:07

I'd love pro tips or feedback on this image of Thistle. Setting included:

Total darkness
Shot on Fuji XT30 / 80mm / ISO800 / F8
Light source is Convoy S2+
I stood the flower in tonic water for a day
Retouched ever so slightly to draw out what I was seeing

Does the image look like there may have been red light leak? I can't tell. Anything different I should try next time in terms of settings?

Thanks!

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#2 Cadmium

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Posted 24 November 2020 - 19:21

Nite, Very nice. I have not seen a 'thistle' in UVIVF before. :smile:
I think that is a Teasel instead of a Thistle.

#3 Andrea B.

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Posted 24 November 2020 - 19:32

What an interesting idea to have the plant absorb fluorescent tonic water! This is a nice dramatic photo.

A plant's chlorophyll fluoresces red under UV light, so I think that explains the red you are seeing.

If you review our suggestions for UV-induced visible fluorescence photography, you will note the use of filters on both the illumination source and the taking lens. Double filtration ensures that the visible light you are seeing is only from fluorescence and (possibly) from the reflection of the fluorescence off other parts of the subject. Of course, double filtration is an added expense, so not everyone uses it. This is OK as long as you are careful to always state what you used in making the photograph.

((Just in case anyone does not yet know, if the camera is converted, then you *must* put a filter on the lens for UVIVF photography.))

I don't have any links to discussions about "leakage" from the Convoy but I'll go look for some.
Here is the discussion of violet light leak from UV-LED flashlight/torches and the filtration which prevents it.
There are other such posts if you search around.
https://www.ultravio...s-the-blue-out/

The amount of exposure in UVIVF photography is simply a matter of artistic choice. The longer the exposure, the more reflected light you might pick up. Also strong fluorescence will blow out some highlights if the exposures are too long.
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#4 Bernard Foot

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Posted 24 November 2020 - 22:52

Nite - do you know if the marinading in tonic water made a difference?

What state was the thistle/teasel in - was it still green, or is it brown and dried up like all the ones around now?
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#5 dabateman

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Posted 24 November 2020 - 23:37

Wow what an amazing idea.
Letting a flower soak up tonic water is something I will have to try.

#6 Stefano

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Posted 25 November 2020 - 03:29

If the plant is not "living" (if you use a cut flower alone for example, not the whole plant), someone could try highlighter fluids of various colors on the same principle. That's a nice idea.

#7 Nite

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Posted 25 November 2020 - 10:04

This is the original colour/condition of the flower for ref...

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#8 nfoto

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Posted 25 November 2020 - 10:31

A living plant has far greater potential for transporting fluids than a dead one. Anyone reviving wilting cut flowers know they regain the cell turgor (internal water pressure) in a few hours if immersed in water.

A dried or dead plant can only have passive transport of fluids through its vascular system. That is a slow process.

Finally, the 'thistle' here is indeed a teasel Dipsacus sp. Whilst they are prickly enough, they have no affiliation to the true thistles, which belong to the Asteraceae.

#9 Stefano

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Posted 25 November 2020 - 10:45

I suggested using a cut flower because pouring highlighter fluid on a living plant wouldn't be so nice for it. Maybe as you said you can put the flower in water for a few hours and then make it absorb the highlighter fluid.

Coloring flowers with dyed water is actually a popular experiment, at least I have seen it being done in my primary school if I remember correctly. You can even split its stem to color it with more than one color. A white flower of course works best, but you can use any flower you like.

#10 Andrea B.

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Posted 25 November 2020 - 20:08

After years of botanical adventures, I also did not realize a Teasel was not a Thistle.
I found this delightful page which explains things: http://www.botanical...h-thistles.html

Here in the US, I often see dyed flowers for sale some of which are neon orange or neon green. They must have been put into something similar to highlighter fluid. And on Saint Patrick's Day, we see dyed green carnations for sale everywhere. So I'm sure a flower can drink up tonic water too.

currently, I cannot go to the grocery store simply to buy carnations & tonic water because of Covid restrictions. But I have made a note in my experiment book to try this when things are safer. :grin:
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#11 Andrea B.

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Posted 25 November 2020 - 21:18

Added: Instructions for Glowing Flower https://www.thoughtc...g-flower-607613
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#12 Cadmium

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Posted 25 November 2020 - 21:42

I think the teasel was imported to America (not a native species, ?) for use in processing wool.