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My interest in light didn't end when I studied laser physics in Hungary and didn't start in the UK while developing high power lasers. I'm now in Switzerland focused on the infrared part of the spectrum, NIR, SWIR, hyperspectral, multispectral. Continously collecting light: line and area scan cameras, optical simulations, spectrometers, slit goggles.. I'm DIY-optics (dot com) himself. ;) You have a very nice community here, I appreciate being a new member. Hello Everyone

A day in Vienna yielded a couple of comparison shots in UV and IR (700nm). The first one is the Mumok (https://en.wikipedia.org/wiki/Mumok ), the others are from the Belvedere (https://en.wikipedia.org/wiki/Belvedere,_Vienna ). I admit that I didn't get all the subjects from the same angle and due to the focal lengths used the IR photos usually have a bit more surroundings, but the differences ought to be visible nontheless. I find it interesting that the materials used during Baroque are almost black in UV.

I've been to Würzburg before, but that was before my discovery of IR- and UV-photography, so when I had to chance to go there again, last year in summer and this year just a couple of weeks ago, I was eager to take some nice photos there. Looking at them, you might think that apart from the Residenz, the cathedral and Marienberg there's not much to see there, but I didn't have a lot of time, so had to stick to the main sights. I'd love to go back and see the rest. The first set of IR-photos (in 2021) was taken with the EOS 6D, converted to 700 nm, and Canon EF 16-35mm f/2.8. I know this lens shows an unmistakably hot-spot, but when travelling one needs to compromise on gear. The second set of IR-photos (in 2022) was taken with the same camera, and the Canon EF 50mm lens, which does not show a hot-sport, fortunately. All UV-photos were taken with the EOS 6D, converted to b/w UV, using the Soligor 21mm. Residenz (https://en.wikipedia.org/wiki/Würzburg_Residence): Cathedral (interior done as HDR from 3 frames, https://en.wikipedia.org/wiki/Würzburg_Cathedral ): Marienberg ( https://en.wikipedia.org/wiki/Marienberg_Fortress ): Neumünster (https://en.wikipedia.org/wiki/Neumünster,_Würzburg ) Neubaukirche (https://de.wikipedia.org/wiki/Neubaukirche): Marienkapelle ( https://en.wikipedia.org/wiki/Marienkapelle,_Würzburg ), quite big for a chapel, I'd say, dwarfing the maypole: I like this shot, because of the contrast with the newer buildings, and, of course, the usual group of tourists. In VIS, it would be more flashy, due to all the colours. Market hall at Unterer Markt:

Today I show you a few comparative shots of "Schloss Burg": https://en.wikipedia.org/wiki/Burg_Castle_(Solingen) I took the pictures without tripod, so the points of view are not identical. Canon 6D-FS - IR filter 850nm on 1:4 16-35 mm L IS USM at 28mm, 200ASA, f 5.6, 1/30 - 1/125 s. - UV filter stack "ZWB2 with 2 QB21" on Canon EF 1:2.8 28mm AF-lens, 3200 ASA, f 4.5-5.6, 1/30s. The two color images show the UV false colors of purple lilac and dandelion flowers. I hope you enjoy ;) The last two pictures are enlargement of sections

https://en.wikipedia.org/wiki/Fujifilm_GFX100#GFX100_IR Anybody knows about its spectral sensitivity, especially in UV? I'm considering this camera instead of modifying my 50R...

Just a couple of IR images I've taken over the past year or so. Both 720nm Kolari filter and Olympus em5i full spec converted/ First was with the Oly 12-40mm pro and the second with the Enna Munchen I use for UV.

I know this is primarily a UV forum, but having put together my ZBW2 UV filter stack with some cheaper 3rd party alternatives, I've come to realize that I am sorely lacking in overall knowledge regarding light modification techniques and filters. After seeing a post on here showing the Kolari IR Chrome filter I use could be recreated by stacking 3rd party filters together, I tried looking around the forum to see if there were any other interesting combinations or filters. I noticed there isn't a pinned thread or compendium dedicated to comparing various IR and other filters. A dedicated thread/page would be extremely useful for new members such as myself!

This is interesting: https://www.43rumors.com/panasonic-develops-low-cost-fir-lens/ Steve

I have found a local seller who is willing to sell me a used Viltrox 0,71x speedbooster for Sony E for around 100 euros. I would probably mainly use it for my Sony a6000 when shooting infrared. Does anyone have any idea how much does this speedbooster alter the image quality and if speedboosters cause hotspots in IR? Thanks.

Recently, I had the good fortune of photographing a dragon fruit flower (Selenicereus undatus). The flowers of this plant are nocturnal an last for only one night. A full spectrum modified Canon 6D with a Sigma 105mm f/2.8 EX DG Macro Lens was used. Light sources: 365nm Alonefire H42 + 365nm Topcom 18w UV torches with stock front filters 395nm Uranusfire T6 + 395nm Topcom 18w UV torches with ZB2 (similar to BG3) filters LetonPower BB27-1S 27 LED underwater torch with red and blue (450nm) led lights Visible light (with clip in Astronomik 'L' UV/IR cut filter) UV 365nm light with ZWB1 (2mm, similar to UG11) + QB21 (2mm, similar to BG38) filters stacked on lens UVIVF 365nm with Tiffen Haze 2E filter on lens + clip in Astronomik 'L' UV/IR cut filter UVIVF 395nm with Hoya X0 filter on lens + clip in Astronomik 'L' UV/IR cut filter Infrared under white light from LetonPower BB27-1S with Astronomik 642nm clip in IR filter Infrared under 450nm blue light from LetonPower BB27-1S with Astronomik 642nm clip in IR filter Infrared under 395nm UV light with Astronomik 642nm clip in IR filter Regards, Troy C

Don't get too excited. Despite the grand title, the results are a little disappointing. Part of this is the fault of my equipment being insufficient for the job, but a lot of it is apparently the moon's fault. It just doesn't vary that much with wavelength, seemingly! But a negative result is still a result as they say, so here you are... Equipment -TriWave camera (germanium-on-CMOS sensor), which has sensitivity from 350-1600nm -Thorlabs 1" 100mm mounted achromatic doublet lens, AR-coated for 1050-1700nm -Thorlabs SM1 Lever-actuated Iris Diaphragm (for controlling aperture) -Thorlabs Filter Mount with Sliding Modular Inserts (with a bunch of the inserts for holding my filters. These are very convenient. You slide the filters back and forth for quick swaps.) -Various Thorlabs SM1 tubes and C-mount adaptors for hooking things together and holding them at the correct distance. -The filters are a mix of Omega seconds from eBay for NIR, and high quality Thorlabs filters in the SWIR (1200nm+). -INOGENI USB 3.0 NTSC video capture card (because the TriWave is analog output) Software - Custom written MATLAB code for snapping bursts of images and saving them - Lynkeos astronomy software for aligning images and weeding out low quality ones - Photoshop Resolution was severely limited by the optics in this case, although the TriWave is only 640x480. I was using only about 128x128px of that, however, due to the 100mm lens. If I get a longer lens, I may try again with higher resolution. Each of these individual images is boiled down from a stack of 600 photos each, but the Lynkeos software throws out many of the bad frames before the rest are averaged together.

As those of you who have been reading my posts know, I have, excitingly enough, finally upgraded to Sony e mount, and with that comes a number of exciting perks, one of which is the access to a plethora of Chinese made manual lenses, with parameters optimized for the APS-C format. Seeing as I will be selling the kit lens due to its fisheye grade distortion at the widest angle, I am looking for some better general options. I have found a few of those budget lenses that I would be interested in. Please, if any of you know/own any of those, could you please tell me or do a quick test on whether they have IR hotspots? I'd prefer not to deal with that. Here are the lenses of interest. Meike 35mm F1.7 https://www.ebay.com/itm/173977209501 Pergear 35mm F1.6 https://www.ebay.com/itm/233579546640 TTArtisan 23mm F1.4 https://www.ebay.com/itm/144329219471?var=443643921758 TTArtisan 35mm F1.4 APS-C https://www.ebay.com/itm/194174863592?var=494266407073 TTArtisan 17mm F1.4 https://www.ebay.com/itm/144058720886 TTArtisan 50mm F1.2 https://www.ebay.com/itm/313352583838?hash=item48f544fa9e:g:eqsAAOSwXUdgWcY0 Thank you to anyone with input. Edit: After being told I will probably have to see myself since we don't have data on those lenses, I decided to bite the bullet again (god save my wallet) and I purchased a second hand Meike 25mm f/1.8, Kolari actually says this one has no hotspots, but I know the list is not entirely reliable, it said the Canon kit lens had no issue but it actually has a hotspot at 950nm. Regardless. I got it for only 41€, so if it isn't fitting, I can just sell it for the same price. I'll report my findings when I get the converted a6000 back from Germany.

I've been told by some friends fromt the USA that outside of Austria everybody knows "The Sound of Music", of which there is a musical and a movie; both of which most Austrians know nothing about, and the ones that do, know that are one or two slight () factual errors in it, and that it brings busloads of tourists to Salzburg and Mondsee. Salzburg, apart from being famous for the romantic story of Julie Andrews and Christopher Plummer, also prides itself for being the birthplace of one Wolfgang Amadeus Mozart, but probaly fewer people know about him than do about the Trapp family (if you ask Austrians about the Trapps, they'll think you're talking about them: https://en.wikipedia.org/wiki/Trappists.) The main attractions of the town, in terms of photo-spots, are the fortress Hohensalzburg, the Festungsberg with the fortress Hohensalzburg on top of it, the cathedral (very beautiful inside), the Mirabell-gardens (in spring and summer), oh, and did I mention the fortress Hohensalzburg? Since I went in winter and the interior of the cathedral is too dark for UV-photos, you won't be surprised that quite a few of my shots are of ... the fortress If you want to know how the sights look like in VIS, this might be a good starting-point: https://www.salzburg.info/en/sights/top10. I went on a cold day, so didn't feel like carrying a third camera or whipping out my mobile every few minutes. Equipment: UV: Canon EOS 6D, b/w, UV-conversion, Steinheil Cassar-S 50mm f/2.8 IR: Canon EOS 5DSR, full-spectrum, with 850nm filter, Canon EF 24-70 f/2.8 The UV-photos are ISO 1600, the very first one even 3200, f-stop is 8 for all photos, also the IR, and the IR-photos are ISO 400-800, as the day started out overcast, with the sun coming out only later, around noon. With a 670nm, for example, I could have gotten the ISO down pretty far, I reckon. I'm sure I missed some spots from the sensor-dust, especially in the UV-pano, apologies for that. Since the Steinheil is a manual lens, and the 850-filter virtually blackens out the viewfinder, I took a couple of shots with the hyperfocal thingie, but mostly used LiveView to focus, which turned out quite ok. I chose 850nm, because I thought the photos would be extra crisp and clear, but I'll go back in the next weeks and try out 670 or 700nm, in order to get some more colour. Also, I didn't have time to walk up Kalvarienberg, which is the mountain/hill on the other bank of the river, to get some shots of the fortress and the city from there. I also hope to find some of the lesser-known spots, like the place where this Mozart guy was born. Here we go, to start off with two examples of modern art, first something in front of Trinity church (called Caldera), and then the Sphaera, a man on a golden sphere, which of course, unofficially goes by the name of "Mozartkugel" (https://en.wikipedia.org/wiki/Mozartkugel):, both in UV: Next, the cathedral and Franziskanerkirche, as seen from the Festungsberg (first IR, then UV): A few shots of the fortress Hohensalzburg from different angles (judging the distance shots, I prefer UV, because of the clearer separation from the background): A few impressions of bridges and buildings along the bank of the river Salzach (first one IR, the others UV): And finally, two panos, taken from the Mönchsberg, overlooking the fortress and the old town (again, first IR, then UV):

My whiz-bang Kolari Vision flash set arrived today and although my UV filter hasn’t arrived yet, I couldn’t wait, so shot an IR “test “- sort of, considering this non-vis rookie has never shot any IR before….sooo, see below why is my IR as-shot pink? First impression of the flash - the dang thang is almost bigger than my camera. Not what you’d call “handy”, but it has a lot of bells and whistles. I like the idea of having a multispectrum flash in the field, plus the two little focus assist flashlights (UV and IR) are going to be handy. The flash power is pretty stout - light power adjustments and EV adjustments both take some experimentation. I shot consistently one stop over exposed in TTL. Just a start though. I’m used to itty bitty Olympus macro flashes, so this bad boy is a new thing for me. There is a general description of the flash here https://kolarivision.com/kv-fl1-flash-light-the-invisible/. Camera: Olympus EM-1mk2, Kolari full spectrum conversion. Lens: Sigma 30mm DN (60mm full-frame equivalent) Filter: Hoya R72 for IR, Kolari Vision hotcut pro 2 for Vis. Flash: Kolari Vision KV-FL1, with IR cup (850nm) Subject: random sunflowers and daisies from grocery store, probably this time of year in Texas sourced from Columbia #1 Visible, no flash (all these shots are F11.. auto ISO chose 6400 for all of these shots - normally I wouldn't go that high, but the visible didn't look too bad I think. Now I switched to the R72 IR filter and used the Kolari Vision flash with the IR cap. Soooo, why is it pink? I am probably making a baaad rookie mistake(s)? This is as-shot. Details a bit blown out. I wasn't wild about the pink.. expected white... so in Lightroom I threw this pink mess into Nik's Silver Efex.. much better. As-shot, using Silver's neutral preset. Now I'm taking the flash outside to find a cooperative cow to shoot in IR :-)... pink cows maybe? Lots to learn.....

We have the well designed Convoy and Nemo UV torches. Any infrared stand outs? Thanks, Doug A

As the title says, some photos taken at a nearby lake (Weikerlsee) and the river Traun, a tributary of the Danube. This night is going to be pretty noisy, so some relaxation time before Camera: Canon EOS 5DSR, converted to full spectrum (first time I've really used this one) Lens: Canon EF-24-70 Filter: 850 nm IR-filter, plus 9-stop ND-filter I had covered the eyepiece with that thingy that comes with the camera, and the lens hood was on, but I did manage to get some flares where the sun was on the right side and I didn't notice that it did shine on the front filter, oh well. Also, in case you're wondering about the high ISO, I stupidly brought only one ND-filter, so with the f-stop I had to go higher. Still, with the camera it's not really a problem. First a tree by the lakeside, f/16, 60s, ISO 800 Next, a view of the lake itself, f/16, 60s, ISO 800 (with the long-time exposure, the tree in front really gets more attention) I moved over to the river Traun, where a long time ago there had been plans to build a bridge, but because the adjoining area is a nature reserve, the project was abandoned. However, the stubs of the pylons and end-piece were never removed. f/16, 60s, ISO 800 (the left pylon is not very prominent, but I didn't want to wade into the stream, even if air-temp was around 15 °C, this would have been a chilly adventure. The view is towards the confluence of Traun and Danube, so the wood and hills behind the water are already on the other bank of the Danube) Ramp-ruin, of course with graffiti on it. It was quite windy, so actually I'm surprised that the one tree just behind the ramp is pretty sharp, while the ones behind are smeared out, f/16, 180s, ISO 400 The next two are the same motiv, with different exposure times. In a way I like both, with a small tendency to favour the second, f/16, ISO 800, the first 30s, the second 180s And a detail of the ramp-bit, this time shorter exposure time as not to completely wash out the clouds, and with the f-stop setting the cloud is not in focus anyway: f/2.8, 8s, ISO 800

Same settings and equipment as the other flowers in this series, with exceptions noted below. UV 2mm UG11 + 1.75mm S8612 (Convoy S2+) Saturation strongly increased Visible BG38 2mm and DB850 filter (645-405nm) NIR-Red-Green (550-645nm + 835-875nm) Tiffen#12 + DB850 filter, and my usual algorithm for making the IRG, described in the DB850 filter thread NIR Hoya R72 + DB850 filter (835-875nm) SWIR (1500-1600nm, made by the panorama method and reduced for higher resolution) UVIVF under Convoy S2+ and using BG38 2mm and DB850 filters --- Comments: The SWIR looks a lot like the visible but with a lighter disk in this one, enough that I got scared and decided to check if my filter was leaking. However when I stacked it with my hard-coated premium Thorlabs 1200nm long pass (guaranteed >OD5), it looked the same, so I guess it just looks similar by coincidence. If you look at the bottom left of the flower, there is a tiny splash of water on a petal, so you can see that the water, although dark, isn't inky when it's just a thin layer like that. This morning the disk florets had started to open up, and they are white in the SWIR 1500-1600nm band:

I was some days from town for a training with some colleague. So I took the opportunity to take some lovely IR pictures! Enjoy! notice the white stripes. Those are the IR exhaust of the jet stream engines. Nikon D70s, Nikkor 50mm f/1.8D, ISO 400, f/7.1, 5min 30 sec, HWB850

3 photo stitched pano. Infrared 850nm (Schott RG850). Finley Wildlife Refuge. Interesting clouds.

This is from a couple of years ago. Taken with a Nikon D7100 converted by MaxMax, and is a stacking of a few different images using HDRSoft, which complicates the note about what the exposures were.

So I was playing around with a 760, 720nm stack and a 940nm torch. Decided to look at my eye, IR is safe right? Well my eye notices the light, but can't see any illumination. Brings up questions I hope someone knows. MVI_3944_VP8.webm

A photo with 25A red filter (~ 580nm red + IR) a photo with blue filter BG25 (Jena glass 2mm)+ BG39 (Chinese Glass 1mm) the warm and contrasting light of the sunset disappears with the cold-toned filters Toni .

Yesterday I took the opportunity try my first IR's (and some full spectrum). And boy.... this is awesome. I'm quite satisfied. in particular the last IR from the firework. so crisp, so overwhelming. Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/8, 8", fullspectrum; Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/8, 30", fullspectrum; Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/8, 8", fullspectrum; Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/11, 2", ZWB3 (UG5) Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/22, 2", 850nm Nikon D70s, Prinz Galaxy 35mm 3.5, 200 iso, f/22, 2", 850nm

Did some more mountain landscapes! The snow made it all awesome. Hope you enjoy! These are taken in the Sierra Nevada in California at about 10000ft / 3000m These are all done with my nikon coolpix and cheapo chinese filters. The IR is 720nm from amazon, channels swapped and fake colour edited to my fancy. The UV this time are done with a ZWB2 (thanks Fandiyus!) and a BG39 from tangsinuo. The ZWB2 did help a lot with transmition compared to ZWB1, i can get something half decent using rocks instead of tripod. Set 1. Set 2. Set 3. Set 4. Set 5.

On the NIST website you can find a contribution to the reflection spectrum of skin: https://www.nist.gov/programs-projects/reflectance-measurements-human-skin The illustration reminds in part of the absorption curve of water that Andy (Perrin) showed in 2019: https://www.ultravioletphotography.com/content/index.php?/topic/3505-dark-water-and-the-nir-absorption-peak/ To see whether skin actually appears darker in longer-wave NIR, I made the following experiment: I took three photos showing my hand on PTFE. Illumination with a 150W tungsten red light lamp. Canon EOS 6D-FS, EF 1.8 50mm STM As filter I used a ZWB2 (720-820 nm), an IR 950 (890-1040 nm on the sensor) and an IR 950 combined with a UV-IR cut filter (app. 1120-1180 nm on the sensor). The image in the longest wave area is very foggy. I only adjusted the brightness of the RAW images on the Teflon. No further image processing. Observation At 950 nm, there is practically no darkening of the skin compared to the range around 770 nm. Around 1160 nm the skin actually appears a little darker. The piece of black carpeting in the background on the right-hand side appears lighter with increasing wavelength. Complement With a glass of water, the effect is much stronger - as others showed here a few years ago. Even with me (sunlight, same equipment): The "long wave pictures" show an artifact ("butterfly"), which is also created without a lens!