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Recently got a couple of 75mm filters from ebay that were advertised as BG25 2mm, and BG18 2mm. Longest delivery time ever - I think it was over 3 months from buying them to having them arrive. Given they were cheap, I thought I'd give them a go as they fit in 77mm filter rings. Here's the transmission of the one which was advertised as BG25 2mm. The spectra is sort of what I'd expect for 2mm BG25, although overall transmission is slightly lower than it should be for 2mm, especially in the IR region. Some photos from my garden using the BG25. Images taken on a multispectral EOS 5DSR, using a 17-40mm lens. White balanced in Darktable and reduced in size for sharing. No change in the hue of the image during processing, although contrast has been boosted slightly. The white flowers are Ox-eye daisies (white with yellow centers in the visible spectrum).

I was able to capture one of our magnolia flowers before they were all gone. They only last two days. Lighting was two 15W germacidal bulbs for all images as was little rushed as the flower significantly darkens over the exposure time. I used the KSS 60mm macro at its f4 setting, which is closer to F8 I think. I white balanced in photoninja and then was surprised that the smallest file size even when 1160x868 is still 1.57MB. So I saved them again in InfranViewer to get the jpegs down to a reasonable size. So you may be missing all the high resolution detail. I captured many of these in the high resolution mode on the EM5mK2 camera. UVA image of flower, I think I used by U330WB80 improved filter for this image: UVB image of flower using the 313bp25 stacked with U330WB80 improved filter: UVC image of flower using 254bp25 filter: I then ripped off the petals you see to open up the inside of the flower. IR using LP 720 filter: Visible UVA with Baader venus U filter: UVB with 313bp25 and U330WB80 improved filter UVB with 303bp filter stacked with U330WB80 and U340 2mm filters ( there is very little 302nm out of my germicial bulb, I am surprised I could boost this up in Photoninja) UVC with 254bp25 filter:

Wilhelmson, U. 2021. Verbascum speciosum Schrad. (Scrophulariaceae). Hungarian Mullein. Flowers photographed in visible, ultraviolet light and a combination of both. https://www.ultravio...garian-mullein/ Verbascum speciosum Schrad. NO: Praktkongslys SE: Praktkungsljus DK: Kandelaber-Kongelys DE: Pracht-Königskerze EN: Hungarian Mullein References: https://www.luontopo...t/showy-mullein http://alienplantsbe...ascum-speciosum https://commons.wiki...ascum_speciosum Comment: A plant native to eastern Europe and western Asia, Verbascum speciosum is known in many other regions as an introduced species and roadside weed. It is a biennial herb forming a rosette of large leaves and an erect stem well exceeding one meter in maximum height. The leaves are 30 to 40 centimeters long and have smooth edges and pointed tips. The plant blooms in a large panicle with many branches lined with flowers. Each flower has a corolla measuring 2 to 3 centimeters wide with five yellow petals. There are five stamens coated in long white hairs at the center. The fruit is a capsule up to 7 millimeters in length containing many seeds. The Hungarian Mullein is the most common Mullein species in Sweden with branched inflorescence. It is characterized by the fact that all stamens are symmetrically attached and that the two lower stamens also have hair on the stamens. Source: http://linnaeus.nrm....ba/verbspe.html Plants collected and photographed in the southern parts of Malmö, Sweden, October 2019, just before the first night frost destroyed the last flowers. All the pictures below show flowers from the same individual. Flower at the collection site: Images below by the same camera and light source: Camera: Canon EOS 60D, EL-Nikkor 80mm f/5.6 old metal type-lens Light source: two UV-converted Godox AD200 flashes with uncoated Quartz tubes Front of the flower, overviews Visible light Filter: Schott BG38, 2mm BUG3-stack image Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG5, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm Front, close-up BUG3-stack image, Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG3, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm Rear of the flower BUG3-stack image Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG3, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm [Published 3 July 2021].

Today we went on lake Como and of course I took a lot of images, in visible and invisible light. I made some TriColours with infrared in the red channel, visible in the green channel and UV in the blue channel. I still have to improve the technique, but the results are not too bad in my opinion. Camera: full-spectrum Canon EOS M Lens: Soligor 35 mm f/3.5 Filters: UV: ZWB2 (2 mm) + Chinese BG39 (2 mm); VIS: Chinese BG39 (2 mm) (only); IR: Hoya R72; All images taken at f/8 and ISO 100. The channels were obtained by converting the whole images to B&W. Except for the second image, all images are the "raw" stacks, no WB applied. I did apply it in Photo Ninja in the second image by clicking the base of the column at the right. Normalizing the exposure times for the visible images, these are the exposures required for UV and IR: UV: ~200-250 VIS (+UV*): 1 IR: 2-2.6 *The BG39 filter used alone passes visible light as well as UV. The resulting image is almost completely VIS-only, but the sky does have a slight violet tint.

For the large format fans I ran across this company whch claims to have a couple of large format cameras in the works good for UV/vis/IR: http://www.largesense.com/

EDITs on 17 June 2021. If those of you who are interested would kindly contribute a working description of the terms multispectral image and tricolor image, I would greatly appreciate that. I want to get consensus descriptions nailed down so that we can refine tags, Stickies, tutorials and our general discussions such that everyone understands what we are talking about. Here is what I was thinking, but I am entirely open to changing my own thoughts about these descriptions. In my descriptions I am making the assumption that everyone knows what is an RGB channel stack !!! DESCRIPTION A Tricolor Image is an RGB channel stack of 3 images where each image is made from a different sub-region within one of the following broad intervals. Typically three narrowband filters are used to photograph the subject. Ideally, the narrowband filters do not overlap or overlap very little. Ultraviolet [10-400 nm] Visible [400-700 nm] Infrared [700-104 nm] The Tricolor goal is to assign visible colors to photos made with "invisible" wavelengths. The selection of sub-regions may of course be restricted to smaller intervals within these larger categories. Tricolor Example: Red [300-320 nm] + Green [330-350nm] + Blue [360-380 nm] where each filter is a narrow 20 nm UV-bandpass. DESCRIPTION A Multispectral Image is typically thought of as an RGB channel stack of 3 images - UV, Visible and IR -where each image is made within the following broad intervals using either a broadband or narrowband filter. Other combinations can also be considered multispectral such as the UV, Vis and Vis example below. Ultraviolet [10-400 nm] Visible [400-700 nm] Infrared [700-104 nm] The Multispectral goal is to produce an image which might represent the outcome of photographing a subject in mixed light or to make an image which emulates the way an animal or insect might see. Multispectral Examples: Red-UV + Green-Vis + Blue-IR where each image is made under a broadband filter such as the BaaderU or an RG780. Red (entire UV image) + Blue (Visible Green Channel) + Green (Visible Blue Channel) Mix it up and see what happens. The 7 Electromagnetic Wavebands: Nobody can quite agree on the endpoints, so please don't let this bother you. This is not Science Class. There won't be a pop quiz. For example, Wikipedia likes to start Infrared at 750 nm. But any UV/IR photographer would start it at 700 nm because wavelengths in 700-750 nm contaminate Visible (and UV) photos. Gamma Rays X-Rays Ultraviolet [10-400 nm] Visible [400-700 nm] Infrared [700-104 nm] Microwaves Radio Some Sub-Wavebands: Same warning - don't sweat the endpoints. This is just a bit of guidance for general discussion. Near UV.........[300-400 nm] Middle UV......[200-300 nm] Far UV............[122-200] Extreme UV....[10-121 nm] UV-A.....[315-400 nm] UV-B.....[280-315 nm] UV-C.....[100-280 nm] Near IR (NIR)...........................[700-1400 nm] For the typical reflected IR photographer I think we would use 800-1100 nm. Shortwave IR (SWIR)..............[1400-3000 nm] Mid-wavelength IR (MWIR).....[3000-8000 nm] Longwave IR (LWIR)................[8000-15000 nm] NOTES: 1) Neither Tricolor nor Multispectral imagery is new. It's been done since the film (both still and movie) days. It is definitely much easier to make such images these days using digital files. 2) Yes, certain single dual bandpass filters or really wide filters might produce results which could be considered either Tricolor or Multispectral. Some light from such a filter is likely going to "contaminate" some other light, so the result may vary from what can be obtained with an RGB stack. Besides which, where's the fun?

Finally, after years of having my filters attached to a cardboard/tape roll, I mounted them in appropriate filter rings. This improves versatility a lot. I took a UV, VIS and IR image of a plant to test multispectral stacks. The filter rings allow me to change my filters without moving my camera (at least, reducing the forces on the lens). I didn't refocus, and I didn't align the images, so enjoy some chromatic aberration. The paper tissue was used as a white balance target. UV, VIS and IR images white balanced in-camera, stacks white balanced in Photo Ninja (it provides better results than IrfanView). This time I worked with .tif files, so the quality should be better. Camera: full-spectrum Canon EOS M; Lens: Soligor 35 mm f/3.5. Filters: UV: ZWB2 (2 mm) + Chinese BG39 (2 mm); VIS: Chinese BG39 (2 mm); IR: Hoya R72. UV (f/8, ISO 100, 8 s exposure): VIS (f/8, ISO 100, 1/125 s exposure): IR (f/8, ISO 100, 1/60 s exposure): TriColour (IR = red, VIS = green, UV = blue): IRG: GBU: Notes: - My Chinese BG39 is not the best filter to cut UV/IR, because it doesn't cut UV at all (at least, most UV) and it suppresses the reds too much. But this is what I have at the moment. - IRG and GBU should be quite known abbreviations here, but to recap: An IRG image has infrared in the red channel, red in the green channel and green in the blue channel; A GBU image has green in the red channel, blue in the green channel and UV in the blue channel.

We had a rainbow today, and I had to try some invisible light photography on it. My camera caught some drops of water, but nothing to worry about. Cameras: Samsung Galaxy A40, front camera (visible); Full-spectrum Canon EOS M (UV, IR, full-spectrum); Lens: Soligor 35 mm f/3.5. Filters: UV: ZWB2 (2 mm) + Chinese BG39 (2 mm); IR: Hoya R72; No filters for the full-spectrum image. Visible light (f/1.7, ISO 40, 1/2370 s exposure). Image cropped to approximately match the others: Infrared (f/8, ISO 100, 1/250 s exposure): Ultraviolet (f/8, ISO 100, 1 s exposure): I have an image with more exposure, but the rainbow is less visible. Full-spectrum (f/8, ISO 100, 1/1000 s exposure): The camera is very sensitive in full-spectrum. If I had the lens wide open, I would have overexposed at ISO 100. Also, the lens has quite a bit of chromatic aberration with a band this wide.

Sulley (James Patrick Sullivan) is the blue monster in Monsters & Co. I had a peluche of him when I was a child, which then became one of Sugar's many toys (our dog). It was very well-made, and resisted for months, until one week ago Sugar was able to tear his head open. He managed to tear apart one of his eyes clean, and I kept it. I imaged it in visible light, IR TriColour and UV BiColour. Gear: Camera: Full-spectrum Canon EOS M Lens: Soligor 35 mm f/3.5 Filters: IR: Hoya R72 UV: ZWB2 (2 mm) + Chinese BG39 (2 mm) No filters in the visible light image Channels: IR: Red: 940 nm Green: 850 nm Blue: 730 nm UV: Red: 365 nm Cyan: 340 nm The light sources were all LEDs. Visible light. f/8, ISO 100, 1/2 s exposure IR TriColour: UV BiColour: Notes: - All images taken at f/8 and ISO 100, with varying exposures; - I set the camera to auto exposure, as it is easier and faster to work this way. If I understand correctly, IrfanView white balances images by re-weighting the channels, and this is why it can't set a UV WB. It doesn't create non-existing channels (this reminds me of this conversation). This "feature" is actually very useful when doing TriColour images, as it compensates for the different exposures of the channels, without altering the colors; - The UV BiColour image doesn't look very good for two reasons: the first one is that running my 340 nm LED at 100 mA produces very little light, and considering I used ISO 100 and f/8, that meant 20 minutes of exposure, and they weren't even enough. This resulted in a very dark image that needed to be lifted up by several stops. The second reason is that, for reasons unknown to me, the program I use to stack the images (ImageStacker) doesn't work properly if one of the images has been processed in Photo Ninja. I had to process the dark 340 nm .CR2 image using Windows Photo editor (it handles raws, surprisingly), and this may have impacted the quality a bit. Also, the LEDs weren't in the exact same spot, and the shadows on the paper tissue below show this. - The three images (not the single channels, but the finished images) were not taken exactly in the same spot, and cannot be stacked. By changing the filters I couldn't keep the camera still, and it moved a bit. I will try to improve my technique. I have to make the tripod sturdier, and when I will have better filters (that actually screw on the lens) and a nice collection of light sources as well as filters, I will be able to do more. For now, not too bad.

(scroll down for a multispectral stack) The flower is on a prickly-pear type cactus (Opuntia sp.) near my house. Nikon D610-conversion + UV-Nikkor 105/4.5 Visible: Baader UV-Cut Filter f/16 for 1/160" @ ISO-400 Click for 1500 px width. This bee was finding life good. Ultraviolet: Baader UV-Pass Filter f/8 for 1/60" @ ISO-1600 Click for 1500 px width. Sometimes the UV gods smile upon us and the bee stays relatively still. I hardly ever crank it up to 1600, but I'm happy I did that for this one.

Just two quick photos, me in IR and UV a few hours before turning 20. Camera: Full-spectrum Canon EOS M Lens: Soligor 35 mm f/3.5 Filters IR: Hoya R72 UV: ZWB2 (2 mm) + Chinese BG39 (2 mm) f/8, ISO 100, 1/200 s exposure f/8, ISO 6400, 1/30 s exposure I look so much different in the two images...

In sunshine with EL-nikkor 80mm and 1.5mm ZB2 and 2mm S8612 stacked filters. Nikon D800 full spectrum. The Marsh Marigold , Caltha palustris was shot against water which here has a magenta cast on the water, the other shots are common daisies, Bellis perennis with a dandelion, Taraxacum officinale, then a white dead-nettle, Lamium album. Not sure if the backgrounds are too blue, or what one would expect with this combination. First time I’ve experimented with this. Tried initially doing a white balance as per a UV only image- looked wrong, so then white balanced off a grey scale instead as if in normal light. The ZB2 is meant to be something similar to a BG3? Its almost an Yves Klein blue. Caltha palustris Bellis perennis with Taraxacum officinale Lamium album.

Stefano (2021) Canis familiaris Linnaeus, 1758[2] (Canidae) Domestic Dog. Dog photographed in ultraviolet and infrared light. LINK Camera: Full-spectrum Canon EOS M Lens: Soligor 35 mm f/3.5 Filters: UV: ZWB2 (2 mm) + Chinese BG39 (2 mm) IR: Hoya R72 The first images are UV: f/4(?), ISO 6400, 1/30 s exposure (repost from here): f/4(?), ISO 6400, 1/30 s exposure f/(?), ISO 25600, 1/15 s exposure f/(?), ISO 3200, 1/30 s exposure. A bit out of focus, but I like it: These last two are IR: f/(?), ISO 100, 1/60 s exposure f/(?), ISO 400, 1/500 s exposure. Starting with the raw image, I increased the saturation to the max in Photo Ninja. Then saved it as a .jpg, opened it in IrfanView, increased the saturation to the max again, and swapped the red and blue channels (BGR).

I just received 2 of theses camera I am about to test awaiting adopters to mount a a F mount lens and able to mount to telescope too. I have costal 105mm uv lenses a uka UV 25mm cmount lens and a keyoei and clones and also microscope objectives and so on.... they are going to be fun to play with full monochrome full frame cameras..... Apogee Alta U9000X link to camera specs: http://www.telescope.../pdf/U9000X.pdf c&p The Alta U9000X uses a very large format 9-megapixel full frame sensor with anti-blooming gates, ideal for applications requiring large field of view, such as astrophotography, sky surveys, and radiology. The X version has a 16-bit digitization rate of 1.8 megapixels/second, compared to the 1 MHz for the U9000. • 3056 x 3056 array, 12 x12 micron pixels • 5 MHz 12-bit and 1.8 MHz 16-bit digitization • 32Mbyte camera memory • USB 2.0 interface: no plug in cards or external controllers • Programmable, intelligent cooling to 40°C below ambient • Binning up to 8 Horizontal x 3056 Vertical • Subarray readout and fast sequencing modes • Precision time delayed integration (TDI) and kinetics mode readout • Programmable fan speed for low / zero vibration • Two serial port outputs for control of peripheral devices • General purpose programmable I/O port • External triggering and strobe controls • ActiveX drivers included with every system • Field upgradeable firmware • Fused silica windows • Runs from single 12V supply with input voltage monitor • Compact enclosure • Programmable status indicators CCDSPECIFICATIONS • Astronomy • Radiology • Optical testing • Non-destructive testing HighPerformanceCooledCCDCameraSystem ALTA U9000Xblob:https://www.ultravioletphotography.com/be38c4f3-bb0f-4723-ab1a-9b4477bf188d Imaging Area of CCDblob:https://www.ultravioletphotography.com/55730472-6855-43c1-b57d-0ea464509927 blob:https://www.ultravioletphotography.com/4677f478-a692-4a96-8e6f-41aba68d54f1 blob:https://www.ultravioletphotography.com/30a1ea90-ade4-4225-a1b8-48c4c4ebff81 blob:https://www.ultravioletphotography.com/f6ac8431-f1f9-4c1c-9c69-f24ea3ad8dea CCD Array Size (pixels) Pixel Size Imaging Area Imaging Diagonal Video Imager Size Linear Full Well (typical) Dynamic Range QE at 400 nm Peak QE (550 nm) Anti-blooming Kodak KAF-09000 3056 x 3056 12 x 12 microns 36.7 x 36.7 mm (1345 mm2) 51.9 mm 3.24” 110K electrons 84 dB 37% 64% For complete CCD specifications, including cosmetic grading, see data sheet from manufacturer. PC Interface Max. Cable Length Digital Resolution System Noise (typical) Pixel Binning Exposure Time Image Sequencing Frame Sizes Cooling (typical) Dark Current (typical) Temperature Stability Camera Head Size Mounting Back Focal Distance Operating Environment Cable Length Power Shutter Remote Triggering USB 2.0 5 meters between hubs; 5 hubs maximum (max. total of 30m) 16 bits at 1.8 MHz and 12 bits at 5 MHz 10 e- RMS at 1.8 MHz and 2 counts at 5 MHz 1x1 to 8x3058 on-chip 30 milliseconds to 183 minutes (2.56 microsecond increments) 1 to 65535 image sequences under software control Full frame, subframe, focus mode Thermoelectric cooler with forced air. Maximum cooling 40°C below ambient temperature 0.3 e-/pixel/sec (-20°C) ± 0.1°C D7. Aluminum, hard blue anodized. 7” x 7” x 2.55” (17.8 x 17.8 x 6.48 cm) Weight: 4.2 lb. (1.9 kg) 5,125” bolt circle. Optional Nikon F-mount or Canon FD mount. 1.008” (25.60 mm) [optical] -22° to 27°C. Relative humidity: 10 to 90% non-condensing. Standard: 15 ft (4.5m) 40W maximum power with shutter open and cooling maximum. AC/DC “brick” supply with int’l AC input plug (100-240V, 50-60 Hz). Alternate 12V input from user’s source. Melles Griot 63mm. LVTTL input allows exposure to start within 25 microseconds of rising edge of trigger

Greetings, all. I'm told I should introduce myself in this forum, so I shall. I'm an amateur photographer just getting into IR work (for myself) and UV work (for work). I work at a major university here, and I'm interested applications of nontraditional photography in health & safety. My first project started a few weeks ago, when it occurred to me that many chemicals either fluoresce or absorb strongly in the UV region. Gee, I wonder if we can use UV photography to identify contamination in laboratories? Even well-kept labs are subject to spills, splatters, and other messes that don't get cleaned up effectively. If we can see the location of the contamination, we can work on removing it (or at least immobilizing it so it doesn't get tracked everywhere). I've had luck finding spills of DNA stains using a simple 395nm UV inspection flashlight, so I'm wondering what results I might get from a more professional approach. So I'm looking at uses of ultraviolet photography that are quite different from much of the work people do here; probably closer to forensic work and photodocumentation. (Not that I won't take a few outings to do some landscape and botanical work for practice with the equipment!) I hope that with a little work, I'll be able to contribute to the knowledge base here. I've sourced a Nikon Z6 modified for full-spectrum operation and an older Nikon 50mm lens that's known to pass UV well (checked that with a UV laser). I'm now trying to select filters for UV reflectance and induced fluorescence, both for the camera and for my UV light sources (xenon flash and a couple UV flashlights of differing wavelengths). Any suggestions the community could offer would be welcome. Anyway, that's the long version of an introduction. Regards, Dan Kuespert

This paper is really interesting: https://www.sciencedirect.com/science/article/pii/S2589004221002364 He was able to 3D print and show basically double the color response. Also the current structure allows for UV. But I see others optimizing this to have less overlap and tighter visible detection. This could be a great way to increase response of small cell phone sensors. Update, Just read to the end. Major caveat! All this work was computationally calculated and not yet actually printed on to a sensor. So real life will no doubt be different. I was hoping and thought the color images were real but only simulated. So still remains to be seen what this structure when actually 3D printed on a naked CMOS will do. Hopefully, I will be proven wrong and the models will fit the reality. But as Andy knows I don't believe many of the models as they usually are completely wrong. Only NMR models nearly perfectly, as all the math is known with very few assumptions. So microlenses might be needed or transparency wasn't correctly modeled and may not work at all. Size at this scale matters significantly.

Any suggestions on tags? Today I photographed some bees busy pollinating some dandelions (I think they are dandelions, but there are so many species all very similar...). I had to use high ISOs to keep the shutter speed fast, as bees move around quite a bit as they do their job. The camera was my Canon EOS M, the lens was the Soligor and the filter was my usual one, ZWB2 (2 mm) + Chinese BG39 (2 mm). Most photos were taken wide opoen at f/3.5, some were taken at f/5.6 but I don't know which they are as the camera doesn't know the lens aperture and writes f/0 as a "null" value. ISO 25600, 1/100 s exposure. ISO 25600, 1/40 s exposure. ISO 25600, 1/40 s exposure. ISO 25600, 1/100 s exposure. ISO 25600, 1/100 s exposure.

Greetings !! My name is Ny Ando and I am a PhD students in Electronic and Systems at the Institut Pascal in Clermont-Ferrand, France. My PhD is about creating a semantic multispectral based embedded smartcamera, including multiple sensors : SWIR, Visible, Thermal and Ultraviolet. With the lockdown in France and the lack of hardware, I retargetted my work on making some modification to a physically based renderer called Mitsuba2 in order to introduce the notion of multispectral imagery and to create a dataset with it. As I needed some insight from knowledgeable folks on UV light and matter interraction, I searched and found this forum. My work has yet to produce tangible images as I am now blocked on multiple ideas. For now in the mituba's work and mine, there are the following notions : - light ray interraction with the surface, ie. ray direction, scattering, diffusion, or absorption; - objects' spectral power diffusion and albedo; - sensor quantum efficiency; - camera filter; - and lastly easy sensor quantum efficiency specification, and generally scence description. And so now I am searching for the best way to represent UV light, and Infrared if possible, into the renderer. Hopefully I will get back some feedback and I promise to show you the results once the whole thing works

Greetings from Mount Vernon, Washington, USA! I am grateful to have been introduced and accepted into your community! I am interested in all things light and its use in application. My education is BSEET/ABET from DeVry Institute of Technology, Phoenix 1999. I have eighteen years of engineering and technician experience in the following industries: Industrial Nd:YAG lamp and diode pumped laser markers from 3-100 W at IR/Green wavelengths of 1064nm and 532nm (rofin) Semiconductor stepper & scanner photolithography at UV/DUV wavelengths of 365nm, 248nm, 193nm, and 157nm (ASML USA/Veldhoven at Motorola, TSMC, Texas Instruments, Micron, and IBM) Aerospace metrology laser and radar trackers (Janicki Industries) Commercial HVACR R&D full life cycle product development testing for manufacturing (Legend Brands/Dri-Eaz Products) I look forward to working with you to progress the art and science of Ultraviolet Photography! Create a Great Day! Aaron

Wilhelmson, U. (2021) More Examples of Tussilago farfara L. (Asteraceae) Colt's Foot. Flowers photographed in ultraviolet light. https://www.ultravio...-more-examples/ Locations: 2017, By Arriesjön, Skåne, Sweden https://www.google.se/maps/place/55%C2%B031'04.4%22N+13%C2%B006'09.4%22E/@55.517889,13.1004153,532m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0x0!7e2!8m2!3d55.5178856!4d13.10260382017, 2020, Studio shoots. Collection place: outskirts of southern Mamö https://www.google.se/maps/dir/55.5674758,12.9720855/55.5674758,12.9720855/@55.5673798,12.9721563,79m/data=!3m1!1e3!4m2!4m1!3e1 Wildflower Synonyms: Cineraria farfara (L.) Bernh. Farfara radiata Gilib. Tussilago alpestris Hegetschw. Tussilago umbertina Borbás Other Common Names: Swedish: Hästhov (engl: horse hoof). Also, the plain "Tussilago" is used in Swedish. Comment: My very first botanical multispectral species, showing the very colourful world of multispectral flower images. The photos were originally posted here: The Tussilago is special to me Reference: 1. Rørslett, B. (2013) Tussilago farfara L. (Asteraceae) Colt's Foot. Flowers photographed in visible and ultraviolet light, with fluorescence. 2. Wikipedia (10 Feb 2021) Tussilago. Wikimedia Foundation, San Francisco, CA. Gear for first BUG-3 Photo 2017 Canon EOS 60D-conversion + EL Nikkor Nippon Kogaku 80/5.6 UV/Blue/Green Filter Stack [bG3 (2mm) + S8612 (2mm)] aka "BUG-3" Resized crop. Gear, images 2020: Sony A7III-conversion + Novoflex Staeble Katagon 60/4.5 Godox AD200 Flash Filter: UV-Pass Filter Stack [u-360 (2mm) + S8612 (2mm)] UV/Blue/Green Filter Stack [bG3 (2mm) + S8612 (2mm)] aka "BUG-3" Four Images stacked with Zerene Stacker. UV. Full image, imaging scale ca 1.5:1 UV. 100% detail crop: UV/Blue/Green. Full image, imaging scale ca 1.5:1 UV/Blue/Green. 100% detail crop: More different BUG-5 single images Gear: As above Filters: UV/Blue/Green Filter Stack [uG5 (1.5mm) + S8612 (2mm)] aka "BUG-5" UV/Blue/Green Filter Stack [uG5 (1.0mm) + S8612 (2mm)] aka "BUG-5 - 1mm" Bug-5 and Bug-5 - 1mm, Single downscaled images:

Here's a tricolor of snow on a window. The filters are: 780BP30 - red channel 1064BP25 - green channel 1500 long pass (but probably 1500-1550 effectively because of the camera gain fall off) - blue channel The color channels are BGR essentially because it made the snow stand out better. Alternative is to have magenta cyan snow in RGB. visible: Individual frames: 780nm ("red") 1064nm ("green") 1500nm ("blue")

Today is one year of membership for me. I only uploaded a fraction of the photos I have, and there are some old photos (I already wrote 2 topics about them) which I never uploaded. Back in September 2019, I tried to take UV+IR photos using only 2 mm thick ZWB2, no BG glass. I was really happy on how they came out, nice blue skies and white foliage. Camera was my DMC-F3. I initially white balanced on a paper tissue, and this gave me greenish-yellow foliage and pale blue skies. White balancing on foliage instead produced the results shown below. Some photos are a bit overexposed, but I like them the way they are. Also, I used ISO 1600 for all of them, but I wrote that anyway. I also hope I will be able to write "f/" instead of "F-stop" in the future, as I am not sure if that f-number was the lens only or if there was something else involved. F-stop: f/2.8, ISO 1600, 1/1000 s exposure. F-stop: f/6.2, ISO 1600, 1/250 s exposure. F-stop: f/2.8, ISO 1600, 1/640 s exposure. Polycarbonate blocks UV. This is to show UV was mapped as blue. F-stop: f/7.1, ISO 1600, 1/160 s exposure. F-stop: f/2.8, ISO 1600, 1/1000 s exposure. F-stop: f/6.2, ISO 1600, 1/200 s exposure. F-stop: f/2.8, ISO 1600, 1/500 s exposure. F-stop: f/4.4, ISO 1600, 1/200 s exposure. F-stop: f/2.8, ISO 1600, 1/320 s exposure.

I think this might be the first time I have seen full spectrum captures (IR + visible bands, no mention of UV) of auroras: https://kolarivision...tian-obermeier/

Today I received BG3 (2mm) and decided to test what happens if I use it with unconverted Nikon D600. The result is not quite UV photography so I decided to post it in UV/IR experiences, maybe someone will be interesting how such combination would look like (everything is blue) and what it is possible to do with it. I found such combination can be used in art by applying some base tone curve adjustments in DNG profile editor and then adjusting exposure/temp/tint/blue colour in Lightroom. This inspired me to dismantle my camera today and hopefully it will be ok after removing UV/IR cut filter. Here is original file. Here is how the base tone curve looks like in DNG profile editor. Here are some tweaking results in Lightroom + white balancing in Photo Ninja

Yesterday Stephan suggested me IrfanView as a software to edit images: https://www.ultravio...post__p__39238. I noticed it has a channel-swapping feature, and I really liked it. Below you see some images I have already posted in the forum in the past, but converted in BGR. Image: https://www.ultravio...-1576877461.png Post: https://www.ultravio...dpost__p__31485 Image: https://www.ultravio...-1581372961.jpg Post: https://www.ultravio...dpost__p__33080 Image: https://www.ultravio...-1586374208.jpg Post: https://www.ultravio...dpost__p__34983 Image: https://www.ultravio...-1585946815.jpg Post: https://www.ultravio...dpost__p__34909 Image: https://www.ultravio...-1591277922.jpg Post: https://www.ultravio...dpost__p__36235 Image: https://www.ultravio...-1602537628.jpg Post: https://www.ultravio...dpost__p__39198 I remember this comment by Andy: https://www.ultravio...dpost__p__36801 My answer: BGR (both in IR and UV) can sort-of mimic true tri-color images, but the colors are not "exact" (reds are not exactly red, etc. You can see this in the first image in this post), but this can be fixed in post-processing. The biggest issue is that, in both IR and UV, you lack green. You have the extremes, red and blue, but not the middle green band. This technique reminds me of IRG done like Andy did here: https://www.ultravio...chrome-rainbow. Yes, it works and it is quite accurate, but it is an approximation, that (in my opinion) can not replace true tri-color images.