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I Gilded the Lily

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#1 colinbm

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Posted 03 June 2021 - 12:51

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.

Attached Image: 2021 06 03 Oriental Lily 40mm pancake lens cool white light.jpg


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

Attached Image: 2021 06 03 Oriental Lily 40mm pancake lens 365nm LED light CWB.jpg


Oriental Lily, under Quad UVA LED lights, CWB

Attached Image: 2021 06 03 Oriental Lily 40mm pancake lens Quad UVA LED light CWB.jpg


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

Attached Image: 2021 06 03 Oriental Lily 40mm pancake lens Quad UVA LED light + 365nm LED torch CWB.jpg

#2 nfoto

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Posted 03 June 2021 - 12:54

#3 for its information value.

#3 colinbm

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Posted 03 June 2021 - 12:59

View Postnfoto, on 03 June 2021 - 12:54, said:

#3 for its information value.

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

#4 Stefano

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Posted 03 June 2021 - 13:11

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

#5 colinbm

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Posted 03 June 2021 - 13:19

View PostStefano, on 03 June 2021 - 13:11, said:

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 ;-)

#6 Andy Perrin

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Posted 03 June 2021 - 14:54

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

#7 colinbm

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Posted 03 June 2021 - 14:57

View PostAndy Perrin, on 03 June 2021 - 14:54, said:

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 ?

#8 Stefano

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Posted 03 June 2021 - 15:13

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

#9 Andrea B.

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Posted 03 June 2021 - 20:21

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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#10 Stefano

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Posted 03 June 2021 - 20:27

Probably "custom white balance".

#11 colinbm

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Posted 03 June 2021 - 22:10

Yes CWB is Custom White Balance, I used a block of PTFE

#12 dabateman

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Posted 03 June 2021 - 22:45

Yes this looks like an excellent subject to compare 365nm vs 395nm.
I think that might be the difference.

#13 Andy Perrin

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Posted 03 June 2021 - 23:22

I think a tricolor would be very interesting for this one. Do like 395, 365, and 320 or something.

Edited by Andy Perrin, 03 June 2021 - 23:23.


#14 colinbm

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Posted 04 June 2021 - 00:07

Thanks Dave & Andy
I'll see what I can do....

#15 colinbm

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Posted 04 June 2021 - 03:11

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.

#16 Stefano

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Posted 04 June 2021 - 06:37

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.

#17 colinbm

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Posted 04 June 2021 - 06:53

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.

#18 Stefano

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Posted 04 June 2021 - 07:33

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.

#19 colinbm

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Posted 04 June 2021 - 07:51

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.

#20 JMC

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Posted 04 June 2021 - 08:32

Love the colours Colin, especially the metallic look it has especially with the extra 365nm torch. Looks great :grin:
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