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UltravioletPhotography

UVIVF: Nichia 365nm UV LED vs. Nikon SB-140 + SW-5 UV


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Here is an experiment I did testing the SB-140 Flash and a 365nm Nichia LED. They seem to produce very different colors, probably because the SB140 has more light near the 400nm range than the Nichia LED, however I have not yet tested the SB140 against a 395 UV LED, so I don't know experimentally how they would compare.

 

Top row has consistant WB settings throughout all images (5000, 0) so you can see what everything looks like with the same WB settings.

 

Second row of images has the WB "optimized" for each individual image. To me, this means at least one of the following:

A) widest apparent color range

B ) looks as close to how it would look under visible light as possible

C) blue cast reduced by warming up the WB Temperture.

 

The WB/Temperture/Tint was adjusted on the RAW file in Adobe software.

 

Third row shows the spectrographs of the UV LED vs the Nikon flash light sources. I'm not 100% certain the first graph is the graph for my exact LED but if it isn't I think it should be close.

 

Images taken with an unmodded Nikon D800 DSLR.

 

I've done this test on other objects/subjects as well (what is the difference between an object/subject when a photographer is using those terms anyway? It seems photographers use both terms interchangably tongue.png )

 

 

 

Vis%20-%20UV%20LED%20-%20UV%20Flash.jpg

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Hi Evan

One clue is that you are using a stock standard Nikon camera.

Here are a few hints for UVIVF photography, with what you are using.

The Nichia 365 LED lamp will still reach into the visible a little (that's the bit of light that you can see) & needs to be blocked with a U340 filter.

It is also a good idea to block the UV entering the lens further with a L410 or a GG420 filter.

 

This camera will see the IR leak from the SB-140 Flash, very well, again a U340 filter, on the flash, will give less IR & it is usual to block this with an additional IR cut filter like a Schotts S8612, either on the flash or on the lens.

 

I find a Custom White Balance with a white Teflon / PTFE, very useful.

 

There is a guy on eBay, UVIROptics, that sells these specialist filters etc.

Cheers

Col

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Evan, I have noted your post here, and I will try to get back to it later with some more comments. :D

 

Your Photographs: Always mention camera, lens, filter and illumination so that people will know what kind of photo you have made. It is sometimes useful to mention aperture/speed/ISO. These values are meaningful for UV or UVIVF photography because they can indicate information about whether UV light levels were low/high, filters were thick/thin, etc.

 

They seem to produce very different colors...

As can be seen from the charts you have posted, the 365nm UV-LED has a much narrower UV output than does the SB-140. (Yikes, man! Where did you find one of those??) Range of output affects both UV-Induced Visible Fluorescence colours and reflected UV false colours.

 

WB "optimized" for each individual image....

You are shooting visible photographs under UV illumination? Is that correct? That is to say, UV-Induced Visible Fluorescence (UVIVF), yes?

Did you use a UV-blocking filter on the lens? If not, then you have some kind of mixed UV/Vis/IR photograph which would be difficult to standardize unless a white standard - invariant under all three types of light - is used. If a UV-blocking filter was used to prevent stray contamination, then we generally attempt to match the white balance to what our eyes are seeing. White balance in UVIVF is difficult. None of us have satisfactorily worked it out yet. [Note: we do have absolutely nailed reflected-UV white balance though!!]

 

More later about Visible or IR light leakage from UV-LEDs and filters. And about white standards. Meanwhile search on "Labsphere Spectralon PTFE Teflon" to learn more about that.

 

Col has mentioned some specific useful hints in his post above.

All of here are always happy to answer questions.

If we don't quite explain things the first time, keep asking. ;)

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Just a comment from the sideline, en route to Ireland: the SW5 UV filter with an SB-140 leaks *a lot* of IR. Not of any significance in the film age in which these products were designed, however a disaster in disguise for digital UV unless you take mitigative measures. I no longer use the SW5 UV with my SB-140s and rely on the UV bandpass filter over lens/inside camera instead to block the unwanted IR.
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"It is also a good idea to block the UV entering the lens further with a L410 or a GG420 filter." - but with an unmodded D810, don't these cameras have UV/IR cut filters in front of the sensor that would do the job just fine? After all, the sensor probably doesn't pick up UV light all that well compared to visible light (although I've been told every sensor is different), and if I am using a regular non-UV lens, then that would also minimize UV light coming through, and the amount of IR leakage coming from the LED probably isn't a lot, right?

 

Can you post an example image of what something looks like with and without one of those filters, taken with a camera that has a UV/IR cut filter in front of the sensor, so we can see how significant the difference is?

 

I just ordered a glass-only filter for my UV LED and may post example images showing what it looks like with the filter on vs off once I get it. I tried it with the Baader-U a while ago and it makes a big difference on certain material (removes the purple), but on other material there doesn't appear to be any significant difference.

 

So white Teflon tape is a very good material to use as a white balance target for UVIVF photography when using a 365nm UV LED?

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You can get UV light through an unmodded D810 (not easily) and non-UV lens. More importantly you can easily get IR light through which may very well contaminate any Visible photo or Ultraviolet photo.

 

Summary of filtration when shooting fluorescence: http://www.ultraviol...who-needs-them/

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  • 3 months later...

Comparison test of SB-140 UV filter, comparing what the image looks like with and without UV/IR cut filter on lens

 

unmodded Nikon D810 with 18-55 lens, f3.5, ISO12800, 1/250th

SB-140 Flash with SW-5 UV filter (see above post for spectrograph)

WB set to maximum warmth in camera (10,000 Kelvin)

 

Left to right:

  1. I believe this was using UV/IR cut on lens. Seems to create more dynamic differences in colors.
  2. using no filter on lens
  3. using on-camera flash for visible light comparison (no sb-140)

 

post-79-0-35686500-1446227409.jpg

 

When doing the same test with a filtered MTE-301 UV LED, I am finding that I am getting no difference in colors when comparing images using the Baader UV/IR cut and without using the Baader UV/IR cut

 

 

Here are some leafs on grass taken with the SB-140 with SW5UV filter, the special/unique property of the SB-140'S SW5UV filter is that it apparently emits some red, so what you are seeing is UVIVF + red + violet, which is actually kinda cool in my opinion, although excluding the violet could make it even better, depending on what you are trying to do

post-79-0-76475400-1446229246.jpg

 

and here is the top left picture with white balance custom set and vibrancy cranked up, this maximizes the color dynamics on the leafs to make them pseudo-rainbow-like. If only there was a brighter light source, I could make some very colorful scenes using this technique

post-79-0-08729300-1446229620.jpg

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That red & blue shot is indeed really cool.

And also the rainbow leaves.

You made some art, man !!

 

Thanks for getting out there with those autumn leaves and giving us some timely seasonal shots.

I need to try some of that too before the lawn crew arrives with the leaf blowers.

 

How about one of those Blak-Ray B-100 lamps like Damon uses? Would that work for you?

Here is a link about the lamp: Blak-Ray® B-100 AP Lamp for UV & UVIVF Photography

There are links with some cool fluorescent stuff:

Mushrooms and friends

Everyday things that Fluoresce under UV

Taking a closer look

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I was asking about that just recently over on this thread: http://www.ultraviol..._7091#entry7091

I am wondering how a Blak-Ray compares to the MTE-301 UV LED, as I already have an MTE-301. Based on the words Damon was using, it sounds like the Blak-Ray isn't brighter than the MTE-301. I'm looking for something suuuper bright and powerful, enough to light objects 2 meters away at F8/ISO100, and enough to overpower the visible moonlight during long exposures. With so much power I am wondering if it would be dangerous to use a light like that, considering all the radiation that would be pumping out of it.

 

Also I did some more tests, expanding on this idea of mixing UVIVF with visible red (this isn't the best object to photograph but it gets the job done for the comparison test and is the only place where I can go to eliminate ambient light during the day lol):

post-79-0-45850900-1446255154.jpg

post-79-0-68525700-1446252898.jpg

 

Adding just a bit of red to the mix can make the images more interesting, depending on what you are trying to do. Sometimes in a UVIVF photograph, everything pretty much looks blue. Adding in different visible colors could potentially make the image look more dynamic.

 

Another test I'd like to try sometime is basically have a mix of 80% UVIVF and 20% of full visible spectrum. I am not aware of any filters that do this, but maybe overlaying 2 separate photos in Photoshop could get the job done and could potentially make an image with lots of interesting colors all over the place, but still natural-looking and pleasing-looking, depending on what was photographed, who knows

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How are you handling the white balance on these photos? I've never been able to settle on what WB to use. I think Damon mentioned that Daylight seemed to work well enough for his fluor shots. I think mine mostly look like what I'm seeing when I shoot.

 

Probably the upper left gives a good mix. There's maybe too much IR contamination in the upper right shot?

The upper left has that same interesting red/blue effect you got in your shot of leaves on lawn.

 

Only problem is when your UV lamp induces red fluorescence in the first place. Shoot the leaves of a nice green houseplant to see chlorophyll fluoresce red. It's cool. But I'm thinking that if you added any more red to that it wouldn't work? Maybe try it and see sometime.

 

Scary isn't it when you photograph something like your sink or stove for fluorescence or in UV. :lol:

 

I mentioned in that other thread that I went to the MTE website, and they do not mention a thing about the strength of their UV flashlights. You might have to set up your own test of Blak-Ray vs MTE !!

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why didn't I think of that? Of course that must be IR contamination, I donno why that swept past me so easily, it must have been because I was thinking IR = white in picture with custom WB, but in reality IR = RED in picture because the white balance is at 10,000k. So you are right, the red seen in the picture probably originates from IR being emitted from the flash, not visible red being emitted from the flash. Either that or it is a mixture of both

 

proper white balance for UVIVF depends on the picture and material i would think, but for me, the default standard I have been using currently is this: I set the white balance to the warmest possible setting in camera, which, on my D810, is 10,000 Kelvin, then if I need to adjust it later I do that in Adobe Camera RAW or in Lightroom. You can adjust the WB further to more extreme values (meaning even warmer than 10,000k) in Adobe Camera RAW or in Lightroom

 

Daylight white balance when shooting UVIVF seems to have a blue over-cast to everything (similar to how shooting in IR in Daylight WB would have a red over-cast over everything) and because I want maximum apparent color diversity, I have been warming it up to balance it out. This is not always the case though and I'm thinking 5,000K-5,500K (Daylight) is the other standard to use, in addition to the other 3 standards i wrote about in the very first post of this thread

 

Here is an example of a green plant that turns red when UV light is shined on it:

first picture is with U-340 Filter + IR Blocker on modded flash, second image is U-340 only. WB set to 10,000K

post-79-0-55898000-1446348507.jpg

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Don't know for a fact that it is IR in that foto, but likely there is some with the U-340. Or as you note, a mix of red & IR.

 

Good experiment with the plant's red fluorescence.

 

So is your goal with the Kelvin settings at 10000K to have the photo look like the reality? I must try that setting. I've never quite gotten my fluorescent photos to have accurate colour! Fluorescent experiments are good for slow dark winter days which will be coming up fairly soon. :lol:

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well usually when I significantly warm up an image for UVIVF, I am doing that because it seems to increase the color diversity in the image which I think is interesting, and also yes it looks more like real life usually. The same principal can be applied to regular non-fluorescent color images as well.

 

Take this image for example:

https://dl.dropboxus...47/_DSC6457.jpg

 

1st image is custom WB (warmer than daylight), notice how the leafs are mainly green, how they would look in real life

2nd image is Daylight setting

 

I may have done a few other things to the image than just the WB and hue/sat. to get it to look like that, I would need to go back and look though

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By the way - the upper images of the sink show classic signs of red (and possibly a little blue) light leakage from your "UV" flash source. Check out the chrome ring around the plug hole. Since chrome does not fluoresce and a UVIR filter is in place, it is reflecting "red" light (probably right around 680nm) from the source. The S8612 has done a nice job of removing that from the excitation source.
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