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UltravioletPhotography

UVF Dead Cicada Specimen


cdhgamer

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Hello all!

 

Thanks to all the help from members on my introduction post, I'm finally able to post my first test photos utilizing UV induced fluorescence.

 

If I'm using any terms incorrectly, please let me know! Also, I wasn't able to fully judge the false colors since I have the orange Ultra-Spec UV safety goggles, do the clear goggles protect your eyes sufficiently to be able to judge false colors? Secondly, do I need to white balance off a target for correct colors, or is that for other types of uv photography? Thanks all!

 

Camera Gear

Nikon D810 / Tokina 100 mm f/2.8 Macro

ISO 31 / f/8 / 1.5 s exposure

 

UV Gear

Convoy S2+ UV LED / Hoya U-340 x 2 mm UV-Pass Filter

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eye4invisible
Some interesting photos there. You might want to try white balancing off of a block of PTFE to see if the colouration changes.
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See, I never know what to do for a white balance in fluorescence. Like, everything in the photo is glowing of its own accord, so there is no light source with a color cast that you could take a white balance of, and have it be more valid. My best guess would be to white balance off PTFE in DAYLIGHT, and then shoot the fluorescence pic in dark as usual but apply that white balance. Then at least the colors would have the same weight that they would have under daylight. But why daylight? Arbitrary choice again!

--

 

These photos are fantastic!

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Some interesting photos there. You might want to try white balancing off of a block of PTFE to see if the colouration changes.

 

I'll have to try one of the targets Steve sells on Ebay.

 

See, I never know what to do for a white balance in fluorescence. Like, everything in the photo is glowing of its own accord, so there is no light source with a color cast that you could take a white balance of, and have it be more valid. My best guess would be to white balance off PTFE in DAYLIGHT, and then shoot the fluorescence pic in dark as usual but apply that white balance. Then at least the colors would have the same weight that they would have under daylight. But why daylight? Arbitrary choice again!

--

 

These photos are fantastic!

 

Thanks so much for the compliment! And so take the PTFE target outside and shoot it in daylight you're thinking for the custom balance? Otherwise it seems like in the sticky, nfoto says that daylight settings should work since it's the visible spectrum. These should have actually been more blue in temperature it seems.

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Yeah, if the camera is not converted then you could use the built in daylight setting, I think? For a converted camera it has to be done more carefully.
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You are sure it is dead?! Those things go through some pretty long dormant periods... ;-) Come on, I am kidding!

Andy, you need to get one of those $800.00 UVIVF white balance targets like Andrea has... maybe barrow her's to try it out.

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Cool cicada fluor! I was maybe a bit surprised that the fluorescence still occurs when the critter is not alive. But then I suppose not all the underlying chemistry has deteriorated.

 


 

Todd: Secondly, do I need to white balance off a target for correct colors, or is that for other types of uv photography?

 

Let's review what we know about white balance in UV-induced visible fluorescence photography. I just rewrote (slightly) the white balance discussion in Sticky :: UV Induced Visible Fluorescence . The discussion is short, so I'll just post it here. But there is other good info in that Sticky, so be sure to review it.

 

A Brief Review:

For our reflected UV or IR photography it seems reasonable to consider 'white' to be a reflection of all of UV, Visible and IR wavelengths. So we therefore use uniformly UV/Vis/IR-reflecting materials such as PTFE or Spectralon as white balance targets in reflected UV/IR photography. Given that both reflected UV or IR photography produces false colours, then, strictly speaking, white balance is not a necessity. But we do it anyway in documentary UV or IR photographs in order to standardize the false colour outcome over differing gear platforms.

 

Analogously, in order to perform white balance for the visible fluorescence induced by UV or IR light, we need some material or pigment which fluoresces white or grey under filtered UV or IR illumination (in the dark). Finding such a material or pigment has been a problem. Clean, uncontaminated Spectralon is
not
fluorescent (as per the manufacturer Labsphere) so we cannot use that. PTFE does often fluoresce but not in a neutral colour, so it too is unusable for white balancing UV- or IR-induced visible emissions.

 

However, recently
UV Innovations
has developed the UV-Grey
TM
fluorescent target for use in white balancing fluorescence photography where emissions are induced with UV illumination around 365nm. UV Innovations also offers the Target-UV
TM
with both fluorescent neutral and fluorescent RGB patches for use in determining the intensity of a subject's fluorescence or for white balance and color checking. The targets use a proprietary coating to produce the fluorescence and are calibrated to certain standard filtration.

 

 

To summarize: We currently have limited capability for white balancing all UV-induced visible fluorescence. But the results using the UV-GreyTM fluorescent target when illumination is provided by a 365nm UV-LED are better than using Daylight or Auto white balance settings. This is not to say that you cannot manage a UVIVF white balance by simply adjusting colours in the converter until they (mostly) look like what you saw while shooting. But anybody shooting technical, forensic or documentary visible fluorescence would probably want a standardized outcome for comparison purposes and would thus enjoy the benefits of the UV-Grey target.

 

 

Links to my experiments:

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