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UltravioletPhotography

I Gilded the Lily


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I brought home this bunch of flowers including this lovely smelling Oriental Lily.

I photographed it under a cool white LED & some different UVA LEDs., with my converted Sigma fp, with Canon 40mm pancake lens, with the Baader U filter.

 

Oriental Lily, under a Cool White LED light, CWB.

 

post-31-0-07044300-1622724300.jpg

 

 

Oriental Lily, under a 365nm LED torch, CWB.

 

post-31-0-86716600-1622724447.jpg

 

 

Oriental Lily, under Quad UVA LED lights, CWB

 

post-31-0-44100400-1622724529.jpg

 

 

Oriental Lily, under Quad UVA LED lights, CWB Plus an extra 365nm torch,

 

post-31-0-80321400-1622724632.jpg

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#3 for its information value.

 

Thanks Birna

This is my Quad UVA LEDs, 365, 375, 385 & 395nm, 90 Watts.

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I like the last one with the golden 365 nm shine.

 

Thanks Stefano

I was just going to photograph in the three lights, then decided to see what some extra 365nm would do, & I liked it as well, with the gilding ;-)

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Andy Perrin
The dark reproductive bits in visible light are light at 365nm apparently? But not in other UV wavelengths.
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The dark reproductive bits in visible light are light at 365nm apparently? But not in other UV wavelengths.

 

Good observation Andy, perhaps Birna & Andrea may make something of it ?

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If so they probably appear false yellow in UV. But maybe they are bright because the torch lit them pretty well.
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what is "CWB"?

 

 

Good observation Andy, perhaps Birna & Andrea may make something of it ?

 

Not sure I can explain the differences. It is certainly possible that lily anthers are UV-bright under one light but not another. But it seems odd.

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Yes this looks like an excellent subject to compare 365nm vs 395nm.

I think that might be the difference.

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Andy Perrin
I think a tricolor would be very interesting for this one. Do like 395, 365, and 320 or something.
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I have 340nm, 365nm & 395nm individual LED light sets I can use for this tri light.

I will set it up tonight, in 6 or 7 hours time. The 340nm is using 8-10 watts, but of course it is only putting out 3 watts if I am lucky, but I can expose for longer.

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Nice to know you have 340 nm LEDs. If they are using 8-10 W, they are putting out 0.24-0.3 W assuming a typical 3% efficiency. This shouldn't be a problem though.

 

Yes, a TriColour image should be interesting. If you can, put a PTFE reference in the images, being careful not to overexpose it. Color here is important.

 

The more I think about it, the more I am convinced the anthers are actually more reflective at 365 nm.

 

I am calling it "TriColour" to stick with the tag. Actually, there are many different ways this technique can be called.

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Thanks Stefano

I have a light with 4 of these 340nm LEDs.

I use the PTFE to get a CWB in camera.

Placing the PTFE in the picture has caused problems for me, as to get the flower properly exposed, it gets the PTFE over-exposed. If I expose for the PTFE the image is too dark. What do you suggest ?

I won't be merging the photos, I haven't done any of this before, I will prefer to send the three DNG files to who ever wants to play with then via DropBox.

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So you have four of these? Did you buy four star PCBs? This is kind of what I want to do one day.

 


The problem with PTFE and UV us exactly that. PTFE is very bright, and most things absorb UV. If I had to choose whether overexposing the PTFE or underexposing the flower, I would choose the latter. The problem is that you can't recover very dark images very much.

 

There are other solutions:

- finding a grey neutral target;

- finding the exact exposures needed to expose PTFE evenly and applying them to the flowers.

 

I think Bernard used both. Here, in "Exposure Factors" he talks about the second technique, and here you can see PTFE in the first images, including UV. I think he can help you more than I can. I never did TriColour in UV, only BiColour images where a paper tissue worked for me.

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Yes, four of those LEDs, I would have preferred nine of then, but I can't justify that.

 

I'll probably take two pictures under each light with a CWB, one with the PTFE not over-exposed & one with-out the PTFE but the flower exposed correctly.

 

The camera will not need to be touched or moved, only the lights will be changed.

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Love the colours Colin, especially the metallic look it has especially with the extra 365nm torch. Looks great :grin:
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I want to do these again as the 340nm seems to have reflected some light around from the Baader ? I will use the D G Industries 40mm enlarger lens & place the Baader in the extension tube

Most of the exposures with the PTFE showing are exposed correctly & the WB in PN is very close to what the camera recorder, only about 200 degrees Kelvin difference, but these shown are with PN WB.

As I said I'll do these again then you can request the DNG file if you want to do the tri-colour.

 

340nm LED.

 

post-31-0-53996400-1622801402.jpg

 

 

365nm LED.

 

post-31-0-15228200-1622801432.jpg

 

 

395nm LED.

 

post-31-0-51956100-1622801469.jpg

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Very interesting and good images Colin,

I like the soft illumination of the Quad UVA LED lights, hat definitely are dominated by the LEDs close to 400nm.

 

The added touch, gilding with the 365nm torch makes it even better.

If anybody is considering soldering LED om metal boards, a solder paste with low melting point makes it easier.

A few of these solder pastes makes it even possible to do on skillet at the stove:

https://www.banggood...e=CN&ID=6282872

One thing to avoid is to put too much paste on the pads.

 

During professional production with solder paste it is distributed on all pads via a metal mask only a few 1/10mm thick.

The paste is then applied in a similar way as screen printing, but it is also possible to manually dispense it into the pads.

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Thanks Ulf

It is funny watching the soldering process, the LED actually floats on top of the PCB & capillary forces make the LED keep in the centre.

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Colin, nice images. Your camera struggle to white balance the 340 nm LEDs, mine too. I too get the blue cast, it's normal.

 

The anthers are definitely brighter at 365 nm, now I have no doubt on that. I know you will make another set of images, but can I already download these and play a bit?

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