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I took this a while ago, but never posted. Image is the top of an orange pepper and yellow pepper in the back. Top of an English cucumber, then tops of a yellow carrot, orange carrot and purple carrot Radish top, turnip and radish bottom. Visible: UVIVF (Using SD15 UV/IR block filter): UVIIRF (Using 720 LP filter): Reduced UVIIRF as the cucumber is bright as a Kiwi fruit. UVIVIRF (Using just a 2A filter to catch both Visible induced and IR induced) UV/Visible (Using just a 2mm S8612 filter with 365nm lights): UV (Baader Venus U with 365nm lights) UV-A (Baader Venus U with 2 UVB lights) UV-B (313bp25 stacked with U330WB80 improved filter):

Here I will talk about the differences between "normal", classic UV (<400 nm), and slightly deeper UV (<380-390 nm). My experience about this is the following: -With nornal UV, you have more colors and more sensitivity. -With deeper UV, you lose colors and sensitivity, but your images will be "more UV" than the normal UV ones (darker polycarbonate, darker sunscreen, etc.). The filter I have used to cut the upper portion of UV is a 3 mm thick ZWB1. For every image I used a full spectrum Panasonic DMC-F3. This is how 3 objects appear with a "light" filter (ZWB2 2 mm + chinese BG 39 2 mm). The ZWB1 in the first image appears yellow because it blocks longer waves and passes shorter ones. In the last image, polycarbonate appears blue for the opposite reason. With the "light" filter, I have enough sensitivity to shoot in the shade, on a sunny day. The 3 mm thick ZWB1 filter, with some glue on the sides because I attached it with tape. ZWB2x2 + Chinese BG39x2 f-stop: f/2.8, ISO 1600, 1/40 s exposure. Plastic lens. ZWB2x2 + Chinese BG39x2 f-stop: f/2.8, ISO 1600, 1/50 s exposure. Polycarbonate goggles. ZWB2x2 + Chinese BG39x2 f-stop: f/2.8, ISO 1600, 1/20 s exposure. When I use the "heavy" filter (3 mm ZWB1), the goggles are completely black, even if I can still see the sun through them. Polycarbonate goggles #1. f-stop: f/2.8, ISO 1600, 1/8 s exposure. ZWB2x2 + Chinese BG39x2 Polycarbonate goggles #2. ZWB2x2 + Chinese BG39x2 f-stop: f/2.8, ISO 1600, 1/8 s exposure. Polycarbonate goggles #3. ZWB2x2 + Chinese BG39x2 f-stop: f/2.8, ISO 1600, 1/8 s exposure. You can see that the goggles are slightly transparent. This doesn't occur when I use the ZWB1 (3 mm) filter. Now, unless otherwise specified, all the following images have been taken with a 10 W 365 nm LED. This LED is very powerful, it can burn paper and wood when very close. I should dedicate an entire topic to it. Visible reference, taken with my phone. Everything is transparent in visible light. The thing at the left is a piece from a broken polycarbonate goggle. UV with 10W 365nm UV-LED f-stop: f/2.8, ISO 800, 1/40 s exposure. UV with 10W 365nm UV-LED f-stop: f/2.8, ISO 200, 1/8 s exposure. UV with 10W 365nm UV-LED f-stop: f/2.8, ISO 400, 1/60 s exposure. UV with 10W 365nm UV-LED f-stop: f/2.8, ISO 800, 1/100 s exposure. Now, this is the difference a 3 mm ZWB1 makes. In the first photo, I didn't use it. In the second one, I put it over the LED to remove the upper 385-390 nm region. The difference is pretty visible. You can also notice that I lost more than 2/3 of sensitivity with the filter. UV with 10W 365nm UV-LED f-stop: f/2.8, ISO 200, 1/25 s exposure. UV with 10W 365nm UV-LED + ZWB1x3 f-stop: f/2.8, ISO 200, 1/8 s exposure. As last images, I imaged the polycarbonate goggles and the small plastic lens with a 405 nm LED, using the usual ZWB2 (2 mm) + BG39 (2 mm) stack, and keeping the usual UV WB. Everything appears blue because UV light in that region appears blue when white-balanced. Those should be 390-400 nm images. Completely transparent lens. ZWB2x2 + Chinese BG39x2 with 405nm LED. f-stop: f/2.8, ISO 800, 1/8 s exposure. The spots on the paper below are burns from the UV LED I talked about earlier. Semi-transparent polycarbonate goggles. ZWB2x2 + Chinese BG39x2 with 405nm LED. Same settings. I have other images, but I don't want to make this post too heavy. I think that this is more than enough for now.

I have thousands of photos, so I will have a lot to post for a lot of time. This time I will focus on some of the spectrums that I have been able to capture, in various ranges. For all shots the camera was a modified Panasonic DMC-F3, which doesn't have anything above the sensor except the lens (and filters). The focal length is always (apparently) 5 mm. I always WB in camera. The source of illumination for the first photographs was a 12 V, 5 W tungsten bulb (used for cars, the 5 W/21 W type), ran at 24 V. I usually intentionally overload incandescent sources, to make them emit light with a spectrum more similar to sunlight. Of course using it like this dramatically shorts its lifespan, and a few minutes were enough to deposit tungsten on the inner surface of the glass envelope. Full spectrum (no filters), f-stop: f/7.1, ISO 80, 1/1000 s exposure. "Sunny" WB. You can easily see the infrared region, but the ultraviolet one is just obscured. Tungsten lamps, although very inefficiently, do emit usable amounts of UV, I even used them for reflected ultraviolet photography. Then, infrared only. I still don't have a proper IR longpass filter, and I used one that I made with black pen ink (not the "liquid" one, made with a black marker, of my first IR photos). The quality is what it is, at the moment is the best filter I have. Infrared (black pen ink filter), f-stop: f/2.8, ISO 400, 1/500 s exposure, 5 mm focal length. Same WB as before. And now the infrared white balanced version, f/2.8, ISO 400, 1/800 s exposure. We can already note two things. First, when white balanced, the shorter IR wavelengths look yellow, and the longer ones look blue. By coincidence, it is the same in UV. And then there is a mysterious absorption line, roughly at something like 960 nm, and I cannot explain it. It is typical of gases an vapours to absorb at a specific, narrow line, but in this case the only gases are inside the bulb and in the air. Taking a photo at the spectrum from a 940 nm LED, we see the same thing. I estimated the wavelength knowing that, from a previous experimental measurement, this LED peaks at 946 nm. 940 nm LED spectrum, f-stop: f/2.8, ISO 80, 1/8 s exposure. This one, instead, is just very strange. Underexposing (in camera, not digitally) an image similar to the third one (white balanced infrared) I obtained a rainbow. f-stop: f/2.8, ISO 100, 1/640 s exposure. The next ones were shot with sunlight. Since I don't have a PTFE target, I used a paper tissue instead. It is one of the closest thing there is, together with snow (in my opinion) to a flat reflectance object. In the next image there are the two 1st order diffraction "rainbows" of the sun, in UV. This is a proof of how narrow and limited the spectrum visible with a UV camera is. f-stop: f/2.8, ISO 80, 1/30 s exposure. Filter: ZWB2 (2 mm) + chinese BG39 (2 mm). Here there is another mystery: beyond the yellow portion there is an orange one. It appears only in some photos and I think that light in that region should appear green, not orange. f-stop: f/6.2, ISO 1600, 1/8 s exposure. Filter: ZWB2 (2 mm) + chinese BG39 (2 mm). And, finally, my best image of the solar spectrum. It came out very well. I think it was a 3rd order diffracion. I left the "clean" version too, so if someone wants to write on it he/she can. f-stop: f/4.4, ISO 80, 1/8 s exposure. Filter: ZWB2 (2 mm) + chinese BG39 (2 mm). The same image, but with the Fraunhofer lines I could identify. from this I can estimate that my camera, with these filter stack, can roughly see from 365 to 400 nm. I know that this post came out pretty long, but I didn't even put everything I had. Anyway, this is the diffraction grating I used.

Hello to Administrator, Thank you for signing me up to the forum promptly despite the fact that we are on opposite site of the earth. I have just started my journey to UV IR and multispectral photography. Converted a Canon 60D to wide spectrrum. Got myself a couple of UV bandpass filter and took some photos. Now am trying to figure out if what I have captured are correctly done. Hope to be able to use the technique for my work in heritage conservation, particularly building and artifacts related. Looking forward to share some photos and any advise related to the matter is welcome. Anyone know of any good training program for this technique? regards Chin Peng

What is the best program for processing Nikon raw files for UV shooting? I use Capturу One now, but i heard that PhotoNinja is better. I have installed PhotoNinja, but i don't know hot can i change white balance in this program. Where in interface PhotoNinja i can change white balance? Could you help me?

The Starlight express Lodestar X2 color is an unusual camera. Its designed to be a guide camera for telescopes. Its very small and just a sensor, guide port and USB port. So you need to have a computer to run it and the computer supplies the power. What makes it interesting though is the sensor in the color version. Its a Sony ICX 829 AKA sensor with a YCMG color filter grid. NOT the typcal RGGB, pattern. its also not a typical array with an odd pattern. The pixel size is huge at 8.4 um, with only 752 pixels by 580 pixels on the chip which is 1/2 size. So the crop factor is 5.4x. Its also a CCD, not CMOS sensor. No modification is needed, and this camera is a CS mount with back sensor distance of 12.5mm. So any lens will mount to it. Using the KSS 60mm F3.5 quartz C-mount lens I was able to test its UV sensitivity using StarLight live software. There is no gain or ISO adjustment for the CCD astro sensors. So you just get shutter speed and aperture on the lens. All were shot with KSS set to F4 (Which is really F8). All images are saved as PNG files in software, I then saved them as Jpeg 75% in Infranviewer to upload here. Flower in visible: Flower using 313bp25 with 330WB80 Improved filter, two UVB lights and shutter speed of 5 seconds: Flower using 303bp10 with 330WB80 imporve filter, single 8W 302nm light and shutter speed of 60 seconds: The software to run it is fun. Its designed for Astrophotography, but allows you to collect dark frames and stack with images. You can live stack images in Sum, mean or median to get better images. It also seems to be the best to interpret the YCMG color array, as the developer worked with the Starlight express to get the true pixel pattern. In it you can adjust the color anyway you want. It changes the way I look at UV false color and you can push almost anything you want. Its fun Flower in visible with Wollensak 25mm lens at F4:

After switching from a Hoya R72 to a Zomei 850nm, I've noticed that images have a blue-ish cast. That never happens when switching from the R72 to any of my B+W IR filters. Re-setting the CWB, gets rid of the blue cast, so I can't complain, considering the cost of these filters. Another interesting anomaly about the Zomei is when you set the CWB, then remove the filter, foliage turns vivid yellow, with a cyan-green sky. Test shot with Zomei 850 (CWB to Hoya R72) CWB set to Zomei 850 CWB set to Zomei 850 Same shot as above, with Zomei filter removed All shots: fs-Sony a7R + 75mm El Nikkor

So, I did a very light editing on this infrared test photo. It is obviously not a award winning composition and frame, but I am curious about the overall impression of everyone on colors and white balance. Thanks!

Came across this on one of my many internet searches. Canon Optron make a material called Fluobright - materials which fluoresce in a controlled way in different colours under UV light. https://optron.canon/en/fluorescent/single_color.html Not sure how one would go about getting a sample of this stuff - the only contact details are for Japan, and I'd be surprised if they are happy to send out small amounts to test. Sharing in case it is of interested for anyone doing fluorescence work.

Some time ago, I started wondering about whether it was practical to have a set of "standard", cheap and easily obtainable materials that reflect in the commonly seen UV false colors. This set of materials would be very useful as an easier-to-use alternative to bandpass filter strips like the "Sparticle" (these filters are expensive and made in small series, so future availability is questionable) and to specific flowers (available only in particular regions and seasons). This is only a starting attempts, and I am the first to object to my initial choice of test materials: plastics are very often mixed with additives, UV blockers, plasticizers and a host of other chemicals, usually undocumented. Many of the common "plastics" have specific names, but can actually be a mixture of different chemical species, once more, usually undocumented. Nylon is an example. Nonetheless, I/we have to start somewhere. In this test I left out PTFE, since we already know it is a good reflector of UV with a relatively flat spectral distribution, so not useful as a false-color target. Here is a set of five plastic sheets in VIS, all except the bottom one chosen because they are white/whitish and, according to the seller, natural (i.e. not colored): From top to bottom: "Nylon" Unplasticized polyvinyl chloride (uPVC) Polypropylene (PP) High-density polyethylene (HDPE) Light-grey colored plastic box, most likely polypropylene (PVC) with added colorants, plasticizers and possibly UV absorbers and the same in UV with Sony A7 II, Coastalopt 60 mm Apo, Baader U, Bowens 1500 Pro studio flash with non-coated Bowens tube, custom WB set with this equipment in sunlight. They all are fairly "white" in UVA, with the exception of uPVC and the (likely) PVC box, which have the same blue false color. Not much to show as a result, except that PVC and its uPVC variant seem to be a reasonable candidate for a false-blue target (the exact blue or violetish-blue shade depends in large part also on the CWB used). This could be a start.

I have lately stared to try to measure reflectance with my spectrometer setup. As this kind of measurements are new for me it is likely that my methods and results are not optimal. I hope to lean more and look forward to comments to improve the method. Equipment: Ocean Optics Flame-S XR1 array spectrometer, range 200nm-1000nm Ocean Optics DH-2000-BAL, Balanced Deuterium Tungsten Source, 210-2500nm Ocean Optics Premium Grade Reflection Probe Custom distance/angle-piece, for the probe tip, for a 6.0mm probing distance during normal probing angle, (90°). Reference: Virgin PTFE sheet matted with 220 grit sand paper under flowing water. Test Objects: Top row: Reference PTFE, Two DIY references based on this thread: https://www.ultravio...__fromsearch__1 Bottom row: PTFE-based 1µm membrane filters, processed and fresh. (Sempe-BLACK 2.0 on the rear side of a filter, dito seen from the front-side, fresh filters in their container) Note that the membrane filter is very thin and translucent. Resulting spectrograms #1: Top line (black): the probe lifted and put down again directly after the calibration. Shows sensitivity to probe angle and target consistency. Second line (blue) DIY target (UW) medium. Third line (green) DIY target (UW) dark. Fourth line (grey) Seple-BLACK 2.0. This measured reflectance is higher than Jonthan found here: https://www.ultravio...dpost__p__16925 I think the reason is that I applied the paint differently. Resulting spectrograms #2: (Blue line) PTFE-Membrane filter measured from the front PTFE-side. (Red line) PTFE-Membrane filter measured from the rear substrate-side. The reflectance values >100% must be due to fluorescence. The optical power of the light source is significant for the shorter wavelengths The PTFE membrane is very thin and mounted on a different substrate material. It is difficult to explain the results here fully. This type of target might still be OK to use in daylight as there is no UV-C and very little UB-B to excite the fluorescence in the UV-A by the substrate material. It is also possible that substrates for different makes of membrane filters behaves differently. One thing is clear, the PTFE membrane is thin enough to be affected by the substrate and materials behind. Resulting spectrograms #3: Purple line: A PTFE-membrane filter doped from the rear with Semple BLACK 2.0 I wetted the membrane filter well with tap water, placed with the PTFE-side downwards. Then I applied slightly diluted Semple BLACK on the substrate side. When dried the PTFE side was slightly marble patterned grey in colour. It has a rather constant reflectivity with no signs of fluorescence.

Hello all! I'm still very new to this, but I've been working on UV induced fluorescence with a Convoy S2+ 365nm Nichia Led flashlight with a Hoya U-340 2mm filter, and a UVIVF photographer I follow mentioned all my shots were coming out with quite a blue/purple cast and I definitely agree with him. I'm curious to hear what other people think and what might be the solution for any visible leak. If it's a matter of getting a lens filter as well, as I know a lot of people use, could you please recommend a brand and model for the lens filter? Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm ISO 320 / f/11 / 4 s exposure. Temp 6500 / Tint 10 - Cloudy Setting Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm ISO 400 / f/16 / 2 s exposure. Temp 7500 / Tint 10 - Shade Setting Spoon Test Nikon D810 / Tokina 100 mm Macro f/2.8 / Convoy S2+ 365nm w/ Hoya U-340 2mm ISO 500 / f/16 / 4 s exposure. Temp 5500 / Tint 10 - Daylight Setting

Thanks to Bob Friedman, I learned something today that I have wanted to know how to do for many many years. I have a D90, D7000, D7200 that are converted to full spectrum, and I use any filter I want on the front of the lens with them. Bob told me that a full spectrum converted D200 (which had no live view) would white balance all sorts of filters. But I have never been able to white balance ANY filters in the camera models I have, until now! For those who have problems doing a Preset in Camera white balance with IR filters, using some Nikon camera models, here are the instructions, this worked for every filter I tried from 665nm to 1000nm: 1) First, switch your White Balance to Pre "d-0" (I am using a D7000, menus may vary?) 2) With your optical viewfinder COVERED (use the little plastic cover or tape), view a scene in Live View with the camera set to Aperture Priority Mode, note the exposure. 3) Turn off live view and switch the camera to Manual Exposure Mode, and dial in the noted exposure from step 1. 4) Point the camera at the scene you want to white balance, you can't see it because you have the optical viewfinder covered the Live View is turned off, that doesn't matter much, just point the camera, press and hold your WB button, when you see the "PrE" flashing on the top LCD take a photo. If it says "GOOD" on the top LCD, wait for that to stop flashing and return to Live View, and Aperture Priority mode. You will NOW SEE the new custom in camera white balance for the scene in Live View. (for those using a D90, you may want to set your exposure mode to spot when shooting in Live View) I have compared several photos white balanced in camera using Bob's method with the out-of-camera versions white balanced from RAW (NEF), the same shots white balanced with NX2 and NX-D, and you would be amazed how close they look to each other. The really nice thing about this for me is that I can now SEE the actual look of the finished photo in my live view, and even show other people what IR looks like in the field, instead of waiting till I get home to see how photos look. I have not *yet* been able to get this to work with UV only filters or even UG1, U-360, and other such filters. Thank you Bob, this is something I have been wanting to do for years!

AUTHOR'S NOTE I began a re-write of this topic on 29 August 2018. Last Update [30 Aug 2018] Adding more info about UniWB. WB = White Balance UV White Balance in Nikon Converted Cameras Is Impossible As we all know, converted Nikon DSLRs cannot measure an in-camera white balance through any UV-pass filter nor through most IR-pass filters. And, selecting a standard WB settings such as Auto or Daylight produces a raw file with screaming red channel overload. While shooting, all that red makes it very difficult to determine the optimal exposure for a reflected UV photograph because details are obscured and you cannot be sure how many stops to push beyond the already saturated right-hand wall in the red channel histogram. Red overload also makes Live View very difficult to use for focus. However, there are in-camera white balance presets we can make which reduce much of the red overload and make it easier to determine optimal UV exposure. One of those is the well-known Unitary White Balance (UniWB) and the other one I'm going to label Nikon Reduced-Red White Balance (RR-WB). Review of Unitary White Balance (UniWB) for Optimal Exposure Some years ago Iliah Borg of Raw Digger fame demonstrated the benefits of using unitary white balance (UniWB)(1) in visible photography. An in-camera UniWB preset is made using a certain algorithm to force R, G, G and B white balance multipliers as close to 1.000 as possible. This results in an in-camera JPG histogram that is much more accurate for determing optimal exposure and much more useful for enabling the technique of exposure to the right(2). UniWB also produces a very green raw visible file, but that is fixed by re-doing the white balance of the raw file during conversion. Using UniWB for UV photography under a UV-pass filter like the BaaderU results in a dark magenta photo, but does provide the more useful exposure histogram. How well this dark magenta works for focusing through a UV-pass filter using a UV-LED torch or strong sunlight may vary by camera. Setting the contrast and saturation to neutral values will help, so be sure to do that in your camera's JPG settings. Contrast and saturation can always be restored during conversion. The details about how to set UniWB are provided in reference (1), so I will not re-write those in this topic. Here is BaaderU UV photograph in UniWB. . Nikon Reduced-Red White Balance (RR-WB), not quite UniWB but useful. There is another way to change the R, G and B white balance multipliers and pull the overall colour cast back from the red/magenta bias. For lack of a better name, I'm just calling it Nikon Reduced-Red White Balance. [Author's Note: In a former version of this topic I labeled this Ner-UniWB, but that was not a good choice because the R and B multipliers were not close enough to 1.000.] The benefits of RR-WB: RR-WB is very easy to set. It provides an improved Live View. Used with a broadband filter like the BaaderU (peak 350nm), RR-WB gives a preview of some of the false-yellow and false-blue seen in white-balanced UV photo conversions. Other filters will vary on this point. The drawback of RR-WB is that its histogram is not as accurate as a UniWB histogram would be although I have been able to use it successfully to obtain better exposed UV photographs. After working with it for a while, I've gotten a feel for how the RR-WB histogram behaves relative to pushing D610 UV exposures for less noise. BaaderU UV photograph in Nikon RR-WB. . Quick Method for Obtaining Nikon RR-WB Briefly, make an overexposed photo, load it into a WB preset slot and adjust the WB color chart. Make a Very Overexposed Photograph Open the UNFILTERED lens up to maximum width aperture. Set exposure time to 30 seconds. Aim at a very bright, white light source, at a bright sunny sky or at very bright white clouds. Don't aim at the sun, please. Then make the 30" exposure. You should get a (raw) white, very blown-out photograph with a histogram showing only R, G and B spikes. The spikes should either hit the right-hand histogram wall or be very close to it. If a 30 second exposure does not produce this set of right-most RGB spikes, then raise your ISO. In my converted D610, it isn't possible to move the spikes completely to the right. Load the Overexposed Photo into a WB Preset Slot Here I'm arbitrarily using WB preset slot d-4. I usually leave slot d-1 open for any on-the-fly WB presets and make use of the other three slots for permanent WB presets Shooting Menu > White balance > PRE Preset manual > {d-4} > Select > Select image > {select overeexposed white photo} > OK Fine-tune the WB Preset Color Chart You will have to experiment with this a bit to decide in which direction to set the color bias because it will depend on the UV-pass filter you are using. I've used both {B6} and {G6} for the BaaderU. It is possible that you will want to leave the color chart cursor in its central, neutral position. The chart cursor is moved with the control pad on the back of the camera. Shooting Menu > White balance > PRE Preset manual > {d-4} > Select > Fine-tune > {B6} > OK Protect the WB Preset Slot It's a good idea to prevent accidental overwrites. Shooting Menu > White balance > PRE Preset manual > {d-4} > Select > Protect > ON > OK . Some Actual White Balance Multipliers I wanted to list some actual WB multipliers so you could get a better feel for this. You can check your own files using any EXIF reader or using a converter app like Dark Table. Remember, white balance is set relative to the green channel being held at 1.000. Nikon D610-full spectrum with camera's Sunlight WB setting. R = 1.906 G = 1.000 B = 1.391 Nikon D610-full spectrum with camera's Incandescent WB setting. R = 1.227 G = 1.000 B = 2.215 Nikon D610 BaaderU photograph white balanced in Dark Table. In an ideal world, we would be able to set these multipliers in-camera and have a much easier time of it when making UV photos with the BaaderU. :D R = 0.316 G = 1.000 B = 1.344 Nikon D610 Overexposed Photo with no WB fine-tuning. (As described above.) R = 0.602 G = 1.000 B = 0.813 Nikon D610 Overexposed Photo with {B6} green adjustment. (Shown above.) R = 0.547 G = 1.000 B = 0.648 Suggestions for Further Experiments Instead of leaving your lens filterless, create your overexposed photo using the BaaderU -- or any other filter -- to see if you get an improvement in the outcome. Write a program to re-set the R, G and B multipliers in a raw NEF to in such a way that the NEF may be reloaded into the camera and used as a WB preset photo. (One thousand years ago this was possible with the ancient Capture software which was written on papyrus in Fortran.) Experiment with altering RGB multipliers by attempting to measure WB against a monitor filled with a somewhat desaturated colour like (255, 190, 60). That gave me these multipliers: 0.711, 1.000, 2.820. While not useful for UV, it was rather interesting for unfiltered photos. [Note to self: re-check these numbers Look at the techniques in this linked topic to find other multiplier trickery. Given that UV is recorded mostly in the Red channel in Nikons under a broadband UV-pass filter, why not just shoot in the Red channel only? Shoot in Nikon Red using 7.996, 1.000, 0.648. . Examples Using StraightEdgeU-Gen2 This new UV-pass filter has a very blue bias when using converted Bayer-filtered cameras. I thought it would be interesting to see what a photo would look like in UniWB and in Nikon RR-WB. SEU-Gen2 UV photograph in UniWB. SEU-Gen2 UV photograph in RR-WB with {G3} adjustment. Some fine-tuning may be possible to further reduce the purple while shooting. Or use a Monochrome setting while shooting if color obscures fine details. SEU-Gen2 after WB in converter. No other edits. Footnotes (1) http://www.guillermo...wb/index_en.htm In 2008 Guillermo Luijk wrote the goto page for UniWB. If you scroll down to the last section, you'll see the quick white balance method I just described. Luijk observes that this method does not work perfectly for all cameras -- Nikons, for example. But it works well enough for our reflected UV needs. :D (2) Nikon DSLRs are known for having between 1-3 stops of highlight 'headroom'. This means that if you push the JPG histogram as far to the right as possible while shooting, then you can gather more light and make a raw file having much less noise. During conversion you pull the exposure back to normal. There is some trial and error involved in figuring out just how far you can expose to the right with a given camera and a given scene. Illustrations In the next three posts I've attempted to show how using a Nikon RR-WB can improve exposures in both Visible and UV photographs. And I have an experiment showing bad results when using a standard white balance setting for UV photography. Standard White Balance Settings Are Not Useful for UV Photographs Nikon Reduced-Red White Balance (RRWB) Helps Make Better UV Exposures for Nikon DSLRs As always, comments, corrections and links are welcomed. Let us know of your experiences using a Nikon RR-WB setting for UV photography. B)

I thought it would be interesting to see the difference between two old German lenses. Conditions were poor. It was sporadically windy with fast-moving clouds, hot and humid. However, the images below tell us a few things, imo. The exposure was one second at f5.6. In-camera WB on PTFE disc. The only PP was a one-click WB and reduction to 1000px width. GF1, ISO 400, 1s., f5.6, SEU Gen2 for both lenses. Steinheil Munchen Cassar S 50mm f/2.8-16 M42 mount. This is a triplet. http://uvroptics.com/images/SteinheilAWBgood1000px823.jpg The next lens is also an old German glass. A Meyer-Optik Gorlitz Primotar E 50mm f/3.5-16 in Exakta mount. This lens is 4 elements in 3 groups. http://uvroptics.com/images/MeyerAWBgood1000px814.jpg The Primotar has a greater DOF in f5.6 and is considerably sharper. Both lenses show some dark green in the Rudbeckia UV targets. I should have tried a CZJ Tessar 50mm f3.5 as well. Next time.

I assume a little bit of IR leak in the UV photos is responsible for the skin tone, but not sure. Model: Sophia. WB: PTFE. Location: Sydney (Paddington Reservoir, Queen Victoria Building, The Rocks). Editing: Minor edits in Lightroom CC. UV: EL-Nikkor 80mm f/5.6 (metal) /w Φ52mm UG11+BG40. INFRARED (>720nm): 35/1.4 and 85/1.2 with Φ77mm r72 INFRARED (>850nm): 85/1.2 with Φ77mm 850nm IR filter VISIBLE: 35/1.4 and 85/1.2 with Φ77mm BG39

I first mentioned this possible alternative to adjusting white balance for UVIVF at the end of the "frozen outdoor" thread, https://www.ultraviol...frozen-outdoor/ with an example inspired by color processing in astrophotography that compensates for light pollution by subtraction. I hope it can inject some fresh thoughts into the discussion - I am not trying to provide any final answers here. While putting together the examples in this write up I realized that it was more complicated than I initially thought. First let us consider the hypothetical situation where we have a light source that is perfectly filtered to only provide UV and no visible light. Also assume that the camera is perfectly filtered to only be sensitive to light in the visible part of the spectrum. The room where we perform our captures is perfectly dark and the only object that shows any fluorescence is the one we want to photograph. How should the camera be color corrected? I would suggest that since we are working with visible emitted light the camera/lens/filter system should be color corrected for a daylight light source. This is ideally done by color profiling with a standard target and a daylight light source. If we have an unmodified camera and we are able to filter out UV without applying a too yellowish filter an in-camera daylight white balance setting might be a reasonable approximation to what colors a daylight adapted eye will see. (Camera manufacturers are pretty good at factory profiling for daylight light sources these days). In astrophotography, daylight WB is typically used as starting point with a non-modified camera when one care about obtaining correct colors. In our ideal UVIVF capture we are now recording only the emitted light from our object of interest. The parallel to this hyppothetical scenario is similar to recording emitted light from stars and other deep space objects in astrophotography with a camera located in space well out of our atmosphere. However in a practical situation we might have several issues: 1) The UV source was not as perfectly filtered as we wanted and emitted a small amount of visible light that is reflected off the object (typically in the blue-violet part of the spectrum). 2) Our filtration on sensor/lens did not filter out UV perfectly and there is some reflected UV contamination. 3) Nearby objects also emitted visual fluorescence that in turn hit our object of interest similar to a visual light source and was reflected back. 4) Our room or outdoor scene was not as perfectly dark as desired but has some background light that was reflected from our object of interest. All of this is contamination of our signal by addition of reflected light. They could for instance cause the image to take on a cold character, but #4 could cause other effects depending on the nearby object. The parallel in astrophotography is the realistic situation that we are located within the earth's atmosphere with light pollution from a nearby city contaminating our signal. The previous discussion here on color correcting UVIVF has seemed to be about white balancing against (very expensive!) UVIVF standards: https://www.ultraviol...e-fluorescence/ However white balancing applies multiplication factors to all signals recorded, both our signal of interest and the added contamination of the signal under 1-4. In astrophotography it is known that this will cause star colors to become incorrect. It causes color shifts with different signal intensities in the objects of interest. If light contamination has been added to the signal, it should be subtracted to get back to correct colors. https://clarkvision.c...ge.processing2/ Perhaps a similar approach can be taken here with emitted fluorescence. The reflected contamination that was added to the signal under 1-4 can be subtracted instead of trying to adjust with the WB coefficients. In astrophotography this is in practice done by a level adjustment, shifting the bottom of the histogram until the left edge of the histogram peak for the different color channels align so that the darkest tones become close to zero. (Refer to fig 1d in the above link for explanation of how different histogram related levels adjustments work.) This gets a bit more tricky in UVIVF. What could be used is to include a standard that will record reflected light and is not emitting any light. The standard would need to be recorded on site near the object of interest to account for all contamination under 1-4. The light on this standard can then be subtracted from the total signal with a levels subtraction on individual channels as above. Just out of curiosity I brought out my Colorchecker Passport and set it up with some other targets to see what it would look like in UVIVF. I am first showing the visible version lighted by my Niterider Lumina 900 boost LED light at the lowest (200 lumen) setting, My non-modified D7100 was set to daylight WB on all of the following captures: #1 Non-modified Nikon D7100, 55mm f/3.5 micro @ f/8, 0.6s, ISO 100, Nikon L39 filter on lens, Niterider Lumina 900 visual LED source at low setting. Here is the unedited UVIVF version. It was recorded with the D7100 and 55mm f/3.5 micro @ f/8, 30s ISO 100 and UV- painted with a Tank007 TK-566 UV-LED light with a ZWB1 2mm thick filter on the front and an L39 filter on the lens. Interestingly the brightest small white patch near the bottom of the frame is really dark: #2 Non-modified Nikon D7100, 55mm f/3.5 micro @ f/8, 8 sec. ISO 100, Nikon L39 filter on lens, Tank007 TK-566 365nm UV-LED light with a ZWB1 2mm thick filter on the front . For this exercise let us just assume that the small bright white patch at the bottom it is not emitting anything and any color on that patch is reflected visible light contamination. A crop is selected on the patch so that the levels adjustment will only show the histogram from this area: #3 Before and after subtraction of signals in the blue and green channels on the patch: #4 - #5 This is what the uncropped scene looks like after subtracting what is assumed to be light pollution: #6 Same capture as above edited. To compare, here is instead a correction by increasing color temperature in the white balance settings. I had to pull the slider all the way up to 10000K. Note that while subtraction above had a pronounced effect on the darker tones, the increase in color temperature here has more effect at warming up the brighter part of the image: #7 Same capture as above edited. As a side issue it can be noticed that the reflection of the UV LED light in the shiny spoon to the lower right is visible as a violet spot in the above UVIVF capture. I confirmed that in a corresponding UVIIF capture (with my D40x IR-720nm) the spot on the shiny spoon is hardly visible, just included here for the record, Also note that our white patch is now quite visible in UVIIF: #8 IR-modified Nikon D40x (Lifepixel standard ca. 720nm), 55mm f/3.5 micro @ f/8, 30 sec. ISO 100, Nikon L39 filter on lens, Tank007 TK-566 365nm UV-LED light with a ZWB1 2mm thick filter on the front . Below is a detail from another UVIVF capture of the shiny spoon with the UV LED light very close. There is a blue ring caused by lint sticking at the edge and then the violet center. It is reassuring that when viewed through my non-tinted 3M UV- safety glasses only the blue lint is visible, not the the violet center which is only is visible to the eye if I take a quick half-second peek without the safety glasses. As it is unlikely that my eyes or the camera is sensitive deeper into the UV range, this is probably light in the transition between UV and visible light. I feel uncertain how much effect it would have on actual captures. It is not too intense compared to the lint at the edge (The UV light's front glass is also a dark filter that supplements the ZWB1 2mm thick filter that I added on the front): #9 Non-modified Nikon D7100, 105mm f/4 micro @ f/8, 2 sec. ISO 100, Nikon L39 filter on lens, Tank007 TK-566 365nm UV-LED light with a ZWB1 2mm thick filter on the front kept very close to shiny spoon, moderate crop. The white patch on the Colorchecker that we used for the adjustments appeared slightly blue rather than violet. It could also have been due to possible blue light emitted from other objects out of the frame and reflected off the white target. Whatever source, this is what we tried to compensate for by subtraction on the normally white patch. In the second exercise we move back to my scene with the tree stub from the "frozen outdoor" thread. Here is the visible light version again lighted by the NiteRider LED light : #10 Non-modified Nikon D7100, 105mm f/4 micro @ f/8, 0.5s, ISO 100, Nikon L39 filter on lens, Niterider Lumina 900 visual LED source at low setting. As it is not completely dark outside here at this time of the year, let us look at a frame without artificial lighting. Notice that our reference white patch is now much brighter than any part of the tree stub: #11 Non-modified Nikon D7100, 105mm f/4 micro @ f/8, 30s, ISO 100, Nikon L39 filter on lens, only background light. If we want to subtract light so that the tree stub is dark without contamination of light from the night sky but not clipped, we must leave some of the reflected light on the patch. In other words we have a problem compared to the astrophotography situation as reflectance of our reference patch might not be the same as that of the object of interest: #12 Same capture as above edited. (The remaining dark orange on the tree stub is back light from the window of my cabin - I forgot to turn the lights off.) Here is the UVIVF version before any correction: #13 on-modified Nikon D7100, 105mm f/4 micro @ f/8, 30s, ISO 100, Nikon L39 filter on lens, Tank007 TK-566 365nm UV-LED light with a ZWB1 2mm thick filter on the front. To do the subtraction on the UVIVF capture we have to go "by feeling", due to the higher reflectance of the patch, we cannot make the patch dark which would result in severe clipping of light from the tree stub: #14 Same capture as above edited. Applying the adjustment I made on the dark frame without artificial light on the treestub above to the UVIVF capture happened to give almost identical result: #15 Same capture as above edited. (But this adjustments only compensates for light from the night sky, not possible light leakage or UV leakage in filters on UV LED source and lens respectively). Finally here is the correction of the original capture by increasing color temperature to about 8000 K. Again brighter tones get much warmer, compared to the effect on the darker tones: #16 Same capture as above edited. Some thoughts: The corrections by subtractions are tricky due to the possibility of variable reflectance of the object of interest (or even different parts of it) compared to the reference patch. However if adjustments are small may be this can be acceptable (the situation of the outdoor test is not typical but rather extreme). The ideal calibration target should likely be gray rather than bright white while still not showing any fluorescence. Unfortunately the UVIVF signature of the gray patches on the Colorchecker shows brighter UVIVF emittance than the small white patches. There is also the possibility to do the correction "by feeling" but then standardized results cannot be obtained. So we are looking for a suitable (preferably cheap!) grey non-emitting standard. The expensive commercial fluorescence WB targets tested here by Andrea, https://www.ultraviol...iltered-uv-led/ seem to result in the "grey" color on the cold side in UVIVF when recorded with daylight white balance compared to a daylight lit grey object. This confuses me as a color should be the same for the sensor whether it is emitted in the dark with proper filtering or reflected off a gray object in daylight. Is there some inherent coldness in fluorescence that has caused the invention of the fluorescent WB standard targets that are doing an ad hoc. compensation for this? If so we are not seeing the "correct" daylight referred colors but UVIVF colors standardized so that they look good to the eye when using preset white balance on the targets. May be even mild initial correction by light subtraction could be combined with WB/color temperature correction? It would be nice to see experiments from others here with other targets and better scenes closer to a practical UVIVF capture situation and help with searching for grey non-fluorescent targets. Sometimes one can be surprised: when I tested the plastic tray that came with some frozen food and that I used for background in the indoor scene above I was sure it was going to be very bright in UVIVF, but it is one of the darkest backgrounds I have encountered so far. Personally I should look for a better UV cut filter for my lens than the L39. (It seems that the material of my polycarbonate UV safety glasses would have been perfect if the durability and optical properties had been better...) Edit: Numbered images for easier referencing. Edit2: Included more detailed technical info below each capture.

In a dark room I sequentially mounted 7 lenses on a tripod-mounted camera and photographed a ≈365nm UV light source, focusing on the LED. I started with the longest (200mm) lens, and moved the camera closer to the subject so that the LED was of framed to approximately equal size between photos. All photos taken in the center of the frame @ f/5.6, 1/8000, ISO1600 on a Canon 5D mark II + UG11 + BG40, and displayed at color temperature = 2000K and tint = 0. In Photoshop I resized the resulting photos to compensate for any minor differences. I reduced each 45px photo (row 1) to 1px to get an average of the photo, then resized back to 45px (row 2) to sample the resulting color. I normalized the RGB values to those of the 80/5.6 (chosen as this is a well-characterized lens) to obtain % transmittance relative to the 80/5.6 (graph 1, table 1). I also added the estimated brightness of each lens at their maximum apertures. Perhaps the Blue/Green ratio can give us some insight into the depth of the UV spectrum transmitted by each lens. The technique is imperfect for several reasons, but perhaps effective enough for a simple comparison. Specific lens versions: Takumar 28mm/3.5: Super Takumar 49mm filter version Takumar 35mm/3.5: Auto Takumar version EL-Nikkor 80mm/5.6: metal version Takumar 105mm/2.8 original Takumar version (model 1) Takumar 135mm/3.5: original Takumar version (early) EL-Nikkor 135mm/5.6: metal version Takumar 200mm/5.6: Tele-Takumar version I had high hopes for the beat-up old 1958 105/2.8, but alas, the RGB results seem to suggest that it's rather strongly anti-UV coated. While it's not much use to me in its current shape, perhaps the simple 4-group/4-element design might make it amenable to uncoating if I buffed each element with a fine abrasive.

I have read this paper on making & using grey scale patches for UV photogtaphy http://www.researchg...let_photography TABLE 1—Materials used to make a gray scale that can be used for reflected UVA photography. Patch 1 is the lightest patch shown in Fig. 2. The gray scale reflects similar levels of UVA and visible light, see Fig. 1A. Patch MgO (%) Plaster (%) Carbon (%) __1___70______26________4 __2___60______33________7 __3___60______31________9 __4___40______30_______30 __5___20______30_______50 I now have the ingredients for the grey scale patches. I am not sure how these are combined ?? Are these mixing ratios by weight or volume ? Are these mixed wet & left to set OR are they just mixed dry & compressed into a holder please ? Cheers Col PS sorry the table got squashed by the text program :(

With our friend Klaus' kind permission, here is a link to a nice reflectivity comparison of Spectralon, sintered porous PTFE (spPTFE) and virgin white PTFE (vwPTFE). The link points to an article in Dr. Schmitt's ever interesting blog. I don't have any specific experimental results about how much colour cast one might induce using the vwPTFE with its small reflectivity drift between approximately 68-75% in the 300-400nm band. But in my and others' experiences with a typical wideband UV-pass filter, vwPTFE will work just fine. http://photographyof...ectralon-r.html Thanks, Klaus!! :D

I am writing a review on RAW converters for UV photography for the UV4Plants Bulletin. I have used my own images, so all of them from an Olympus E-M1. Some of the test results were as expected, but I got some surprises: i) Photo Ninja could handle the very extreme white balancing needed, while Lightroom 6.9 and DXO OpticsPro 11 could not and images retained a very strong colour cast (nothing new here). ii) Photo Ninja introduced a small scale but very strong mosaic pattern in the white balanced images (at normal magnification shows up as lack of resolution of fine detail). The different "Demosaic" settings had a small effect, but the problem persisted. This could because the E-M1 camera has no antialising filter on the sensor. (The two examples are out of registration, but they partly overlap). Top image processed in Capture One Pro, lower one in Photo Ninja. Question 1: Has anybody seen this with other cameras? Is this a common problem or just specific to the ORF images from the E-M1? iii) When using the eye dropper tool on a target on an image to find the "white" balance of high ISO (noisy) images, each click gives a drastically different white balance in Photo Ninja (I guess the target area is too small). Question 2: Have you experienced this problem? Is there a solution to it? iv) For ORF raw files the free Olympus Viewer 3 does and excellent job at colour balancing UV images. A lot more consistent than Photo Ninja... This was a nice surprise, although the program mostly provides the same controls as for in-camera conversion. v) Phase One's Capture One Pro does an excellent job at both white balancing, and demosaic of ORF images. The only problem I found is that the extreme white balance correction for UV images cannot be copy and pasted between photographs. Question 3: Is anybody in this group using Capture One Pro for UV images? Question 4: Has anybody tried other camera makers' free RAW converters with UV images? Many thanks for any answers to these questions... I do not want to get things wrong in the article. Thanks in advance!

Sharing this in case it is of interest. I found myself wanting a substrate I could use for a white balance with the UV camera, while I have access to a Spectralon disk I wanted something I could keep with the camera and use as and when needed. I did not however want to buy another Spectralon sample. So I got to wondering whether a simple PTFE plate would do the job. A few minutes on eBay and I found someone who could sell a 100mm x 100mm PTFE plate described as being "PTFE Teflon Plate, high temperature, low friction engineering plastics". I bought 2 samples of this material. One I just cleaned with soap and water as there was a small amount of surface contamination. The cleaning worked ok but did not remove everything (I'd say about 90% on visual inspection). On the second one, I gently rubbed the surface with 12 micron lapping film to remove surface debris, which did remove all visible contamination but left small scratches all over the surface. Once this was done I ran both of them on a Perkin Elmer Lambda 650S UV-Vis spectrometer (150mm integrating sphere) to measure surface reflection between 250nm and 800nm (1s collection time per nm). The graphs are shown below, both the full range and the 300nm to 400nm portion. Both the samples showed similar behaviour at the longer wavelengths, but started to deviate slightly below 400nm. However interestingly the the 'cleaned' sample looks to be flat reflectance between 300nm and 400nm, at about 90%. Now this isn't as high as some of the Spectralon samples, but being optically neutral, I'm presuming this should be good as a white balance material for use in that range. Overall cost £3.65 per piece, with larger pieces available if needed. I understand PTFE is used for this purpose, but I'm not sure if the reflectance of a sample like this has been directly measured before. I'd be interested to hear peoples comments or thoughts.

As I started my journey into UV photography I wanted to find a way to calibrate my images for amount of UV being absorbed. Given I had an Xrite Colour Checker chart (one of the cardboard ones about A4 size) I thought that I would try the grey scale part of that and see what it would look like. Yes, I know these have been reported as not being good for UV, but I wanted to see just how bad they are and whether it would be any use. Obviously I know now of other approaches and proper UV calibration standards, but heh, I'm a scientist I like to experiment. To understand how it was behaving in UV I cut up the chart and measured the 6 relevant tiles (white through to black) for reflection on a Perkin Elmer Lambda 650S UV-Vis spectrometer (150mm integrating sphere) between 250nm and 800nm (1s collection time per nm). The graphs are shown below, both the full range and the 300nm to 400nm portion and 400nm to 700nm portions. The 6 lines are the 6 tiles along the bottom of the card, from 1 (white) through to 6 (black). This to me demonstrated just how bad these are for UV. Interestingly though they weren't completely neutral in the visible spectra either, especially at shorter wavelengths and for the lighter tiles.

Update: 14 June 2017 Added links to other experiments Exp 1: First Look at Target-UV & UV-Grey for UVIVF [see Post 7] Exp 2: Target-UV with Stock Cam, Unfiltered Lens & Unfiltered UV-LED Exp 3: Target-UV with Stock Cam, Filtered Lens & Filtered UV-LED Exp 4: UVIVF White Balance with the UV-Grey Target, Stock Cam/Lens Target-UVTM with Stock Cam, Unfiltered Lens & Unfiltered UV-LED Experiment: Shoot the Target-UVTM under unfiltered 365nm Nichia UV-Led illumination using an unconverted stock camera and unfiltered lens. [Added-->] No later in-converter white balance adjustments will be made in this first post. Conclusion: The shot made with the Preset white balance (made against the UV-GreyTM target) was the most accurate in colour in this unfiltered test. The other five WB choices showed color casts. [Added-->] Note that color casts are because no in-converter WB adjustments were made. However, please seePost #7 and Post #10 for alternately processed versions of this composite chart. Equipment: Camera: Nikon D810, stock Lens: Micro-Nikkor 60/2.8G Lens Filter: NONE Lighting: 365nm Nichia UV-Led Flashlight Lighting Filter: NONE Settings: Neutral [0] Picture Control, no sharpening Nikon ADL = off f/2.8 @ ISO-400, various speeds White Balance Series: In Nikon cameras, a white balance may be fine-tuned on a 2-dimensional blue-red/green-magenta grid. The bracketed [0,0] indicates no fine-tuning was applied. In-camera Preset White Balance made against the UV-GreyTM Target under 365 UV-Led light in darkness. 10000K[0,0] -- the hottest K. Direct Sunlight[0,0] -- that is, "daylight" or "sunny" white balance. Incandescent[0,0] -- aka "tungsten". 2500[0,0] -- the coolest K. Auto1[0,0] -- the "normal" auto wb. Description: The experiment was conducted in darkness in my hallway coat closet. The unfiltered UV-Led flashlight was aimed onto the Target-UV from the top of the camera and maintained at the same distance from the Target-UV for all shots. LiveView was used to set an exposure time. Photos were made of the Target-UV under 6 different white balance settings. Photo Preparation: The raw files were converted to TIFs in Photo Mechanic. In Capture NX2, minor LCH curve edits were applied on the Luminosity layer to adjust the same neutral patches to approximately the same brightness on each strip. This was needed because of slight differences in exposure and minor variations in flashlight illumination. (I was hand-holding the torch.) The composite was constructed in PSE 11. WB labels were added in PSE 11. The labeled composite was resized to a high-quality JPG in Photo Mechanic. Observations: Preset White Balance - the Winner: The white balance made against the UV-Grey target under the 365nm UV-Led was the clear winner. Its neutral patches are the most neutral of the series. The worst WB setting: Auto white balance got confused. No wonder when it was trying to see Visible emissions through UV light. Exposure Times: I didn't agonize over the "proper" exposure this time. I just used the LiveView matrix-metered exposure. The Usual Caveat: Converting the raw file and stuffing it into a resized JPG/sRGB box to be posted on a website may alter the colors. This is a known factor. Wobbly Torchlight: Tonight the Nichia 355nm UV-Led Flashlight was bright when I first turned it on but then faded a bit. Is that normal? Well, it certainly is annoying. Therefore I was careful to turn the flashlight off after each shot so that I could shoot the next shot when the flashlight was at its greatest brightness just after turning it on. I wonder if I was entirely successful in this effort? All the clicking and clacking was detrimental to the uniform application of torchlight to the same area of the subject each time. Geez, it's always something. Next Up: Repeat experiment with filtration on the flashlight to cut visible leaks, if any. See Also: Post #7 and Post #10 for alternately processed versions of this composite chart. D810 (stock), unfiltered Micro-Nikkor 60/2.8G (stock), unfiltered 365nm UV-Led flashlight

Update: 14 June 2017 Added links to other experiments. ****************************** Exp 1: First Look at Target-UV & UV-Grey for UVIVF [see Post 7] Exp 2: Target-UV with Stock Cam, Unfiltered Lens & Unfiltered UV-LED Exp 3: Target-UV with Stock Cam, Filtered Lens & Filtered UV-LED Exp 4: UVIVF White Balance with the UV-Grey Target, Stock Cam/Lens First Look at Target-UVTM & UV-GreyTM for UVIVF Yesterday afternoon, I received my two targets from UV Innovations: the UV-GreyTM rectangle, version 1.1 and the Target-UVTMstrip, version 1.1. The purpose of these two targets is to standardize workflow in UV-induced visible fluorescence (UVIVF) photography so that results are repeatable. The intensity of fluorescence can also be determined. This thread will host my initial experiments as I learn how to use the two targets. Here is the link to the UV Innovations home page: http://www.uvinnovations.com/ The targets arrived with a nice foam padded plastic case and with each target also in a protective envelope. You can see everything on the website, but I'll post photos anyway. It's always good to illustrate that the website displayed items were the ones actually received. [Disclaimer: UltravioletPhotography.com, an independent website, has no affiliation with any business. I have purchased the two targets from UV Innovations for the advertised price.] Added: 03 June 2017 UV Innovations provides very good workflow suggestions for using the UV-GreyTM and Target-UVTM. LINK to Workflow: http://www.uvinnovat...getting-started While I like to fumble around reinventing the wheel when learning about new products, please don't think you must follow my twisty path. :D Visible Light: Front of Case Visible Light: Back of Case Or, it could be the other way around. :) The UV-GreyTM rectangle, which is indeed a grey colour in ordinary visible light, is used to set in-camera white balance under UVA illumination. The UV-Grey target in visible colour is inbetween to my Labsphere targets having 20% and 50% reflectivity. However under the Nichia 365nm UV-Led, the UV-Grey target becomes a brighter fluorescent grey while the non-fluorescent Labsphere targets remain dark. One small nit I have about the UV-Grey target is its lack of wider borders for easier handling. I'm a bit worried about fingerprints from skin oils getting onto the target area. (I will ask about whether that is a legitimate worry.) Visible Light: UV-Grey Target with Labsphere Standards The white Labsphere area in the photo was set to 98% brightness. I tried to adjust the tones of the other Labspheres so that brightness was well distributed. Brightness and the conversion curve in a photo converter do not necessarily nor easily equate to Labsphere reflectivity. The Target-UVTM, which has 4 rows of 6 patches each, is used for measuring the intensity of UV-induced visible fluorescence. In each row, three of the patches are grey. The other three are red, green and blue. All patches fluoresce under UVA illumination. The four rows increase in fluorescent intensity from low and medium on one side to high and ultra on the other. Visible Light: Low-Medium Side of Target-UVTM Visible Light: High-Ultra Side of Target-UVTM Yes, the logo is also brighter on this side. The recommended UV/IR blocking filters to place on the taking lens are the Wratten 2E and the Peca 918. The Wratten 2 is a pale yellow, 415nm longpass filter which blocks UV (and some visible violet, it would seem). Do remember, these pale yellow longpass filters like the Wratten 2E fluoresce yellow under UVA, so the Wratten 2E or any equivalent filter must be fitted to the rear of the lens or fitted under the Peca 918. The Peca 918 is a UV/IR blocking filter used here for its IR-blocking properties. However the Peca 918 has about a 2% leak around 700nm. So I'm not sure this would be my ideal choice for IR-blocking. We can do better with our S8612 filters, yes? If I am shooting in an entirely dark closet, the IR-blocking is not a particular worry, but I block it anyway for UVIVF work. I was going to replicate the recommended filtration, but I have decided against that because I can do better on the IR end. And I see no need to wrestle with unmounted Wratten gel filters when I have a nice selection of mounted glass longpass filters. The important step will be to verify that my choice of filtration does block UV and IR as much as possible. http://www.ultraviol...dpost__p__16338