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UltravioletPhotography

Tried some UVIIF, aka Uvi-Irful


Andrea B.

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When I'm using several filters during a shoot, I keep notes as I go along so that later I can properly name the files to indicate filter and illumination used. The acronyms UVIVF (Ultraviolet Induced Visible Fluorescence) and UVIIF (Ultraviolet Induced Infrared Fluorescence) were not distinct enough to decipher in my messy, hand-written notes. So UVIIF quickly became Uvi-IrFL in my notes -- and eventually Uvi-Irful. Pretty bad, I know. But it was helpful....so okay. :D

 


 

I brought a few Coleus clippings indoors to grow in a jar of water because I thought the typical variegated Coleus leaf would be an interesting UV-induced fluorescence subject. (See also Plectranthus scutellarioides.) These tender tropical plants cannot stand even a touch of frost, and a night later the remaining outdoor Coleus plants were completely ruined because our first winter frost was a hard one. Anyway, yesterday I carefully cut one nice leaf to photograph, put its stem into a shallow bit of water in a saucer and set up my still life.

 

For reasons known only the Coleus leaf, it promptly began wicking water out of the saucer while I was photographing it. A few shots in, I noticed the leaf looked a bit wet. I ignored it thinking I had perhaps splashed some water when cutting the leaf. A few more shots later, I could see the lower tip of the leaf was sitting in water. Call me puzzled. I tried to mop up a little using the tip of a paper napkin while trying not to disturb the increasingly damp still life. But by the end of the work, there was a puddle of water under the leaf. This is one of the crazier things I've seen a leaf do during my attempts to photograph it. Now today, the leaf is plump and healty -- and dry except for the stem end in a little vase. I suppose this leaf must have been very thirsty when I was photographing it? Maybe I'll try to start a new Coleus plant from it to have indoors during the winter.

 

Back to fluorescence: Our member Mark has been making some most excellent multi-spectral arrays of flowers and berries which include lovely and fascinating Uvi-Irful photographs. They inspired me to try shooting this kind of fluorescence again now that I know a little bit more about it all than I did the first time. I think I captured some Uvi-Irful, but I'm still not completely sure. I'm also including a few extra UV and IR test shots.

 

Equipment [Nikon D610-conversion + Zeiss UV-Planar 60/4.0]

 

Visible [f/8 for 2.5" @ ISO-400 with Onboard Flash and Baader UV/IR-Cut Filter]

There was also some ambient lamp light when making this photo.

The green areas are from chlorophyll and the dark red areas are from an anthocyanin pigment. Anthocyanins can also produce blues, purples, a dark blue-black and other shades of red.

Look how wet the leaf appears. I had already made a lot of test shots prior to this first good Visible photo.

coleusLeaf_visFlash_uvPlanar_f8_20171118wf_7256pn01.jpg

 

 

Ultraviolet

Two flashes were made during each 15" exposure.

 

UV [f/8 for 15" @ ISO-400 with SB-14 UV-mod Flash and BaaderU UV-Pass Filter]

The leaf is very UV-absorbing to protect its photosynthetic capability. There are some specular reflections in damp areas. Leaf pores are bright green dots.

coleusLeaf_uvBaadSb14_uvPlanar_f8_20171118wf_7262pn01.jpg

 

UV [f/8 for 15" @ ISO-400 with SB-14 UV-mod Flash and StraightEdgeU UV-Pass Filter]

coleusLeaf_uvStraightEdgeSb14_uvPlanar_f8_20171118wf_7271pn02.jpg

 

UV [f/8 for 15" @ ISO-400 with SB-14 UV-mod Flash and MoonU UV-Pass Filter]

coleusLeaf_uvMoonSb14_uvPlanar_f8_20171118wf_7277pn01.jpg

 

 

Infrared

The lens was stopped down to f/16 to increase depth of field in this longer wavelength.

 

IR [f/16 for 1/200" @ ISO-100 with ayz IR-mod Flash and Schott 630nm (2mm) IR+Red-Pass Filter]

As expected, the leaf is very IR-reflective. Those large dark spots are not dust bunnies, rather some bit of mold or other kind of deterioration. The tiny dark specks along the leaf rib are probably just dirt.

coleusLeaf_ir630-2_irFlashMod_uvPlanar_f16_20171118wf_7309pn01.jpg

 

IR [f/16 for 1/200" @ ISO-100 with xyz IR-mod Flash and Schott 715nm (2mm) IR-Pass Filter]

Note the water which has gathered at the end of the leaf.

coleusLeaf_ir715-2_irFlashMod_uvPlanar_f16_20171118wf_7315pn01.jpg

 

IR [f/16 for 1.6" @ ISO-100 with zyz IR-mod Flash and Schott 830nm (2mm) IR-Pass Filter]

It looks like this IR-mod flash has an output in the 700-800 nm range. The exposure time got much longer using the 830nm IR-pass filter.

coleusLeaf_ir830-2_irFlashMod_uvPlanar_f16_20171118wf_7325pn01.jpg

 

 

UV-Induced Visible Fluorescence

UViVF [f/4 for 10" @ ISO-100 with Unfiltered 365nm UV-Led and Baader UV/IR-Cut Filter on Lens]

This is beautiful!!! The green chlorophyll areas fluoresce red (as we have seen before in various plants). Are the dark anthocyanin areas fluorescing? I don't think so, but they do seem to be illuminated a bit from the red chlorophyll fluorescence. The omnipresent lint fluoresces bright blue as usual. The blue dots in the lower right quarter of the leaf are specular reflections off the damp surface.

coleusLeaf_uvivf_uv365LedNoFilter_uvPlanar_f8_20171118wf_7336pn01.jpg

 

 

UV-Induced Infrared Fluorescence

  • These photos were made in the dark. Periodically while shooting, I turned off the UV-Led and made an unlit test shot of the same exposure length as the preceding shot in order to see if there was any ambient IR light leak into the photo. I did not find any. The viewfinder was also blocked.

  • The green chlorophyll areas emit Infrared fluorescence. The anthocyanin areas are not fluorescing. I'm not sure why I still have a couple of little nagging doubts about what I'm doing. Did I do everything correctly? Are there any non-UV wavelengths emitted by my UV-Led that could get through my various IR-pass filters? Was it dark enough? And so forth.

  • I found only small differences between using a filtered 365nm UV-Led and an unfiltered one.

  • The leaf was light-painted with the the UV-Led to avoid torch hotspotting. Light-painting does not always produce an even illumination in a photo. I think I need a bigger UV-Led. It might be time to yoke up some Convoys and retire my little Haiku torch.

  • I opened up to f/4 to shorten the exposure times for the painting-with-UV-Led technique. It's rather tedious.

  • For each combination of IR-longpass filter and 365nm UV-Led (with and without filtration), I made a shot of the Target-Grey rectangle for use in a Photo Ninja white-balance preset to be applied to any photos made with that combo. [The Target-Grey fluoresces grey under UV light.]

UViIF [f/4 for 2.5" @ ISO-400 with Unfiltered 365nm UV-Led and Schott 715nm (2mm) IR-Pass Filter on Lens]

Prior to white-balancing, both 715 photos contained very vivid orange and dark orange tones.

coleusLeaf_uviIRf720-2_uv365LedNoFilter_uvPlanar_f4_20171118wf_7398pn01.jpg

 

UViIF [f/4 for 8" @ ISO-400 with 365nm UV-Led + U-340 (4mm) and Schott 715nm (2mm) IR-Pass Filter on Lens]

No surprise that a 4mm thick filter over my little UV torch caused a bit leap in exposure time over the preceding photo.

coleusLeaf_uviIRf720-2_uv365LedFilter340-4_uvPlanar_f4_20171118wf_7408pn01.jpg

 

UViIF [f/4 for 6" @ ISO-zzz with Unfiltered 365nm UV-Led and Schott 830nm (2mm) IR-Pass Filter on Lens]

It took longer to get the 830 photos, so the Coleus IR chlorophyll fluorescence is obviously between 700-800 nm. (We've looked that up before. It's somewhere on UVP.)

coleusLeaf_uviIRf830-2_uv365LedNoFilter_uvPlanar_f4_20171118wf_7372pn01.jpg

 

UViIF [f/4 for 20" @ ISO-zzz with 365nm UV-Led + U-340 (4mm) and Schott 830nm (2mm) IR-Pass Filter on Lens]

Note the water which has pooled on the leaf and to its left.

coleusLeaf_uviIRf830-2_uv365LedFilter340-4_uvPlanar_f4_20171118wf_7385pn01.jpg

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Andrea, Very nice!

Very nice to see the comparisons between the 715nm and 830nm filters shots.

Have you tried it with visual/green light? That needs to be filtered to keep the green/visual from leaking into the IR.

 

Acronym: If we use "UV" to express Ultraviolet, then why do we (some) use only "I" to express IR/Infrared?

I have been using UVIIRF. If Infrared is "I" then is Ultraviolet "U", thus UIIF?

Or is this acronym already well defined?

I suppose the smaller case "i" makes some sense to separate the UV from the IR or I, but then should the F also be smaller case ("f")? UiIf? UViIRf?

 

By the way, to those who use facebook, there is a very impressive green induced 715nm IR fluorescence shot of broccoli on this facebook group right now:

https://www.facebook...ef=group_header

 

[Admin: Try this link instead and click "NOT NOW" if you get a pop-up.

The broccoli is really pretty, very frosty.

http://www.facebook....52&type=3&ifg=1 ]

 

Here is a visible green induced 665nm IR fluorescence.

post-87-0-44624000-1511233276.jpg

 

This one is visible green induced 715nm IR fluorescence.

post-87-0-64654300-1511233600.jpg

 

Some comparisons (sometimes I have used the term LUM to describe IR fluorescence, a term I have seen used prior to my use).

post-87-0-29267700-1511233683.jpg

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By the way, to those who use facebook, there is a very impressive green induced 715nm IR fluorescence shot of broccoli on this facebook group right now: https://www.facebook...ef=group_header

 

Unfortunately that link is not accessible unless you have a Facebook account.

Try this one: http://www.facebook.com/photo.php?fbid=1541643169250688&set=gm.1422000364583352&type=3&ifg=1

 

 

 

But I'm confused as to how green light can induce IR fluorescence in broccoli? Broccoli is green. So, in theory anyway, broccoli reflects green light and cannot therefore absorb green light to excite any kind of luminescence. Are you sure that green light was used?

 

LUM for "luminescence" ?? Luminescence is a general term for light emission not caused by heat. Fluorescence is a kind of luminescence. Also phosphorescence is a kind of luminescence. There's probably others, but can't recall right now.

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By the way, to those who use facebook, there is a very impressive green induced 715nm IR fluorescence shot of broccoli on this facebook group right now: https://www.facebook...ef=group_header

 

Unfortunately that link is not accessible unless you have a Facebook account.

 

Yes, that is why I said "to those who use facebook".

I am not trying to promote or sell facebook to anyone who doesn't like it or use it, just posting a link if anyone wants it. That was all.

Some people here made an issue about this last time I posted the link.

 

But I'm confused as to how green light can induce IR fluorescence in broccoli? Broccoli is green. So, in theory anyway, broccoli reflects green light and cannot therefore absorb green light to excite any kind of luminescence. Are you sure that green light was used?

 

LUM for "luminescence" ?? Luminescence is a general term for light emission not caused by heat. Fluorescence is a kind of luminescence. Also phosphorescence is a kind of luminescence. There's probably others, but can't recall right now.

 

Yep, green light. You can use full RGB visual if you want, but you will need to filter it to green to separate the visual (red) from the IR range, especially if you are using lower longpass IR filters, such as 715nm, etc.,

and often most visual light contains not only red but also IR, and you don't want to illuminate the target subject with any IR light.

Also, it would be best to remove any possible UV light from the visual light, that way defining the excitation wavelength. So filter out any UV and Red/IR light for VIIRF.

UVIIRF is easier with our Nichia UV torches, in the sense that those have fairly narrow UV bandwidths and IR doesn't need to be filtered out.

In fact, my first ever VIIRF shots were done using a Maglite (brand) flashlight (which had an older incandescent type bulb in it) which was filtered with a green filter stacked with thick S8612.

Now I use a green LED flood light which is also filtered.

 

Thank you for your definition of Luminescence. You are totally correct that luminescence is a larger category than fluorescence.

I agree that fluorescence is the more appropriate and technical term than LUM, just explaining why I used it on the photos.

Not saying it is the correct or best term to use, but maybe as correct as some various acronyms...

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Afaik, there are no generally accepted name strings or acronyms for all these fluorescence techniques. So whatever name string or acronym anyone wants to use is fine with me as long as the poster defines it somewhere at the beginning of the topic so we all know what we are reading about. And I have now just reminded myself to go back to my post and do just that because I don't think I did. :D

 

I thought there was a way to link to FB so that the Log In message does not appear?

 

Recently everyone here I know is talking about how they are dropping their little used Facebook accounts because of all the political shenanigans. I quit going there because the pages are always so messy and full of boring, irrelevant junk and ads. But I have no objections to anyone posting links to FB.

 

Still puzzled about that green.

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The green is not a big deal, what is a big deal is to remove anything below or above visual range, and if you want to use lower longpass IR filters, then you need to remove red also, thus green light is a little like narrow band 365nm UV light, which is not a full range of UV-A. Nothing wrong with using full range UV-A, or full range Visual, but much like we filter 365nm UV torches to prevent visual blue contamination in UVIVF shots, also we need to filter visual light to prevent it from contaminating the IR fluorescence shots. This also goes for red, if using lower longpass IR filters, and even UV if you want to make sure there is no UV exciting the target. Thus green light works best.
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Would my green filter be useful for this? It was a VG-9 I think.

I have a green LED also. Perhaps combine the green LED with the VG filter.

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Indeed, VG9 is what I used. What thickness is your VG9?

You could test the filtered light to see what light is transmitted, using various longpass filters in live view.

The upper red/IR limit is mostly important pertaining to the longpass IR filter used on the lens.

Here are a couple graphs to give you a few ideas.

 

post-87-0-52713900-1511242391.jpg

 

post-87-0-59153800-1511242512.jpg

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You could also try thick S8612 stacked with GG420 (or higher), which would give you a visual range light.

You could use Baader UV/IR-Cut filter, however it transmits a lot of red, but it would work for higher IR longpass filters. I have been told it also leaks some small amount of UV, but how much I don't exactly know.

S8612 and BG39 cut the most red per thickness.

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Great shots Andrea. I also often have second guesses about the UVIIF (UVIRF, etc) shots I capture - I think because they tend to be very similar to IR images (understandably, since its IR either way). I think a test would be good; one which includes the 'shiny metal ball' and a known IR reflective material, together. Shooting those two under my UVIIF conditions should illustrate whether I have IR leakage/other in my configuration. And if not, well, then I could conclude that whatever illumination is being captured must be only from induced IR. Does that sound about right?
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The Hoya G (X1) and Marumi P01 (Green) are similar to VG9. They have almost identical transmission and come with AR-coating.

I got my Marumi here: https://www.ebay.com...K/221616666513?

 

Transmission curves with and without S8612, 2mm:

 

post-150-0-89649000-1511351165.jpg

 

post-150-0-29072900-1511351150.jpg

 

The attenuation in the IR range is uncertain as the sensitivity of the spectrometer setup is not very good there.

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