• Ultraviolet Photography
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Amethyst UV

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#1 Craigk79

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Posted 16 June 2021 - 00:11

Am I seeing this red in my shots because I am not filtering the lens?

Attached Image: Amythist.jpg

#2 Stefano

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Posted 16 June 2021 - 00:49

Especially if you are using a converted camera, probably the purple on the surface/table you see is UV. Do you have anything that blocks UV (like polycarbonate goggles) to test this? Or you can do the opposite, if you have a UV-pass filter that blocks visible (and preferably infrared) light, and you still see this glow when you put it on the lens with the same camera settings, then it’s UV.

#3 Craigk79

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Posted 16 June 2021 - 00:51

I am looking into getting a uv ir cut filter

#4 Craigk79

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Posted 16 June 2021 - 00:57

You can see more clearly in this image. What is the red sneaking into my images.


Attached Image: _OEC8149.jpg

#5 Stefano

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Posted 16 June 2021 - 01:06

It could be two things: fluorescence or UV.

Since you see red reflections on the stove, I'm guessing it's UV, and I think I can even say it's 365 nm UV. That wavelength appears reddish when a "normal" visible light white balance is set (that's my personal experience and I have seen this 365 nm color on UVP too). A pure fluorescence image should not contain direct mirror-like reflections.

#6 Craigk79

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Posted 16 June 2021 - 01:11

View PostStefano, on 16 June 2021 - 01:06, said:

It could be two things: fluorescence or UV.

Since you see red reflections on the stove, I'm guessing it's UV, and I think I can even say it's 365 nm UV. That wavelength appears reddish when a "normal" visible light white balance is set (that's my personal experience and I have seen this 365 nm color on UVP too). A pure fluorescence image should not contain direct mirror-like reflections.
That is why I am not sure about a uvir cut filter? Any advice on this would be appreciated.....

#7 Stefano

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Posted 16 June 2021 - 01:18

There are a lot of filters that can be used. Some fluoresce a lot, some fluoresce less. If you haven't read it, I suggest reading the UVIVF sticky to find more information.

Since I never actually tried UVIVF myself (except with my phone), my experience is very little compared to other members here who did it much more. They can probably help you more than I can.

#8 colinbm

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Posted 16 June 2021 - 01:36

What is the light source ?

#9 Craigk79

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Posted 16 June 2021 - 01:53

Yongnuo yn 560iii Hoya U-340 and Schott S8612

Edited by Craigk79, 16 June 2021 - 01:56.


#10 Craigk79

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Posted 16 June 2021 - 01:58

I think I need a cut filter for my lens.. not currently using one.

#11 colinbm

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Posted 16 June 2021 - 02:59

Yes you need a visible light camera for UVIVF or a 'Hot Mirror' on the lens.

#12 Andrea B.

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Posted 17 June 2021 - 21:42

I'm going to use the word "proper" informally. There is no requirement from UVP that you use double filtration for fluorescence photography. Of course we would urge you to do so. :lol:

Proper UV-induced Visible photography requires:
  • a filter on the illumination source to ensure that only UV light reaches the subject.
  • a filter on the taking lens to ensure that only Visible light reaches the sensor.
  • photography in the dark to avoid ambient light contamination.
  • placing the subject on a non-fluorescent background.
.
And please remember that even if a non-converted stock camera/lens is used to record the Visible fluorescence,
such gear can still sometimes pass a bit of either UV or IR. So stock gear must filtered too.

I'm curious about how well you can filter a flash like the Youngnuo? They are so strong that unwanted light could possibly get through the filtration?

Usually when we see that violet/purple color we say it is due to leakage from the illumination source.

All this is written up here: <> Sticky :: UV Induced Visible Fluorescence <>
In particular scroll down in the Sticky to read about the Shiny Metal Test which shows the violet/purple color.
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#13 Craigk79

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Posted 17 June 2021 - 22:31

I think as another member kindly pm'd me to say that my 3d printed part is leaking ir. I am now conjuring up an idea to coat it in something to block it.

#14 Andrea B.

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Posted 17 June 2021 - 22:36

Let us know if you were able to block it. :smile:
Andrea G. Blum
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#15 Andy Perrin

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Posted 17 June 2021 - 22:43

If it's the material itself leaking IR, maybe you could paint it with some of that Semple Black 3.0?

#16 Craigk79

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Posted 17 June 2021 - 22:59

Thanks guys sure will let you know. I did consider paint also considering rubber. Or maybe even just foil tape for now. I am guessing the light leaks through the layers as I have seen 3d printed boats that need to be sealed before use. I am new to this world of UV and am learning as I go along. Thinking about this stuff

Edited by Craigk79, 17 June 2021 - 23:02.


#17 Andy Perrin

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Posted 17 June 2021 - 23:40

Don't use any paint or sealant until you test that it's opaque to UV and IR as well as visible. Plenty of things are "black" in visible light but white or transparent in IR.

#18 Craigk79

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Posted 17 June 2021 - 23:52

I will get some gaffers tape and seal it up with that for now. Thanks for the tips I appreciate it

#19 Craigk79

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Posted 18 June 2021 - 01:16

foil and gaffers tape should seal it right?

#20 Andy Perrin

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Posted 18 June 2021 - 01:52

Yes, nothing will go through foil. It's just not the most elegant method.