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UltravioletPhotography

Other tri-color IR images


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I started this new topic since I thought the previous one was already complete, being my first attempts only. I have taken other images, and I am posting them here.

 

This is the first topic: https://www.ultravio...t-tri-color-ir/

 

As a reminder, the camera I used is a full-spectrum Panasonic DMC-F3, I used a Hoya R72 filter for the IR images and a white LED for the visible light references. Some tri-color images have been white balanced, I will say that for every image. Note: sometimes my camera doesn't autofocus, and usually (ironically) the IR images are sharper than the visible ones the camera was designed to take.

 

Channels:

Red: ~940 nm;

Green: ~850 nm;

Blue: ~730 nm.

 

Visible reference:

post-284-0-62970200-1606686612.jpg

 

Tri-color IR (original):

post-284-0-40674400-1606686649.jpg

 

I don't think I need to say this, but to be clear the brands shown are just random and there isn't the slightest intent to advertise them.

The first bottle from the left is water, the third one is denaturated alcohol 90°. They both appear bluish, but the alcohol is greener.

 

Pens, assorted colors. If the colors aren't clear, from left to right they are BLUE RED BLUE GREEN GREEN BLACK BLACK BLUE RED BLUE.

Visible reference:

post-284-0-09378700-1606687441.jpg

 

Tri-color IR (original):

post-284-0-44397800-1606687470.jpg

 

Full-size crop:

post-284-0-49866100-1606687491.jpg

 

Some inks became transparent (red), others orange (blue), others red (green) and the black pens remained black. Black pen ink becomes transparent to IR when thin (see my pen ink filter).

 

Rodolfa

 

Visible reference:

post-284-0-36679100-1606687990.jpg

 

Tri-color IR (original):

post-284-0-44783300-1606688082.jpg

 

Amethyst (I am 99.9% sure it is that)

 

Visible reference:

post-284-0-47158700-1606688261.jpg

 

Tri-color IR (white balanced):

post-284-0-40198200-1606688311.jpg

 

Various minerals

 

The rock/mineral below has a quite strong orange fluorescence under 365 nm UV.

 

Visible reference:

post-284-0-29680100-1606688476.jpg

 

Tri-color IR (white balanced):

post-284-0-83944000-1606688526.jpg

 

Visible reference:

post-284-0-06881700-1606688740.jpg

 

Tri-color IR (white balanced, almost identical to the original):

post-284-0-68738900-1606688757.jpg

 

The middle specimen is actually green:

post-284-0-23208600-1606688813.jpg

 

Visible reference:

post-284-0-56138000-1606688962.jpg

 

Tri-color IR (white balanced, similar to the original):

post-284-0-67906300-1606688968.jpg

 

The middle specimen is actually blue:

post-284-0-04641900-1606688974.jpg

 

Bonus: a failed attempt. I tried to photograph an orange, but it slowly settled down and thus moved a bit. I processed the images anyway and this is the result (crop):

post-284-0-60182600-1606689211.jpg

 

Thoughts and conclusions:

 

White, red, orange and yellow plastics come out usually white;

Blue plastics are usually yellow;

Green plastics and dark blue plastics are usually orange/brown;

Black plastics are often black.

 

Most minerals don't have strong IR false colors. Except for one strong yellow, all I got were shades of orange and pink, and a very pale blue from the amethyst.

 

I think I will take other images, probably 3-6, and I will post them here. If you have any suggestions (I am running out of ideas!), please share them here.

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I will re-try the orange. I should either give it time to settle or use a support.

 

Also, I tried a hand. I had to use my dad's hand, and the skin came out mostly white, maybe a tiny bit blue, and the hair on his arm became orange.

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Yes, one day I will try fluorescence, both visible and infrared. The pink rock may be similar to a pink highlighter: they are both pink and they both fluoresce orange. Probably the fluorescence keeps going into IR, and in tri-color IR (with filters) it may be blue, since far red appears blue with this technique.
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Ok, I have other 6 images. Now I really ran out of ideas, probably I will be set for a while. All tri-color IR images have been white balanced except for the heatsink one.

 

Orange, take 2

 

Visible reference:

post-284-0-94730500-1606755986.jpg

 

Tri-color IR:

post-284-0-95132900-1606755998.jpg

 

It seems my LEDs weren't perfectly aligned... but this is good enough for me.

 

Bananas

 

Visible reference:

post-284-0-42486900-1606756084.jpg

 

Tri-color IR:

post-284-0-51905100-1606756209.jpg

 

10 € banknotes, front and rear. What surprises me aren't the disappearing regions, this is a well-known trick in IR, but the colors I got. I have yellow, red and even blue, which isn't common in tri-color IR (except for water, sky and some filters).

 

Visible reference:

post-284-0-89054700-1606756400.jpg

 

Tri-color IR:

post-284-0-99882300-1606756417.jpg

 

Below is the heatsink I use with my LEDs. I don't have just one, this is one I didn't use yet. The black paint/coating becomes transparent in IR, and from the golden color it is clear that the absorption decreases as the wavelength increases.

 

Visible reference:

post-284-0-61370600-1606756618.jpg

 

Tri-color IR:

post-284-0-38938200-1606756633.jpg

 

Solar panel. I was expecting something interesting, but I was disappointed. Black in visible and IR, and probably also in UV.

 

Visible reference:

post-284-0-54071900-1606756821.jpg

 

Tri-color IR:

post-284-0-33921100-1606756832.jpg

 

Piggy bank, even though pigs are a bit different...

 

Visible reference:

post-284-0-26831600-1606756977.jpg

 

Tri-color IR:

post-284-0-98066400-1606756993.jpg

 

I really like this technique. Time-consuming and suitable only for static subjects (movement is your biggest enemy here), but in my opinion it is worth it.

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Stefano, you might want to retry the solar cell but very close up or macro even. Also the results will be very angle-dependent for the solar cell due to the thin layers involved.

 

The bank notes were interesting. I tried doing one of ours in SWIR (1500nm-1600nm) once:

post-94-0-35945300-1606780453.jpg

post-94-0-55618500-1606780467.jpg

 

post-94-0-13200100-1606780475.jpg

post-94-0-97849700-1606780488.jpg

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Thanks Andy, I will try the solar panel again. I don't think I can do macro, but I will try to be as close as possible.

 

It seems all banknotes or at least most of them have disappearing portions in IR. Usually NIR is deep enough, but SWIR of course works well.

 

US dollars have a disappearing rectangle (as you showed), and a green line in UVIVF. Euro banknotes are beautiful under UV. They are pretty much full of patterns, and have yellow and orange rings. I think the older ones were better, they had nicer patterns. If I find an old and a new one, I will try to post some UVIVF images (my first)!

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