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@Stefano two years ago I published here, a basic table of the transmittance at 365 nm (similar to the Kolari test) I used a Nemo 365 nm light with ZWB2 filter, positioned behind a 150x150 x3mm thick tefloflon sheet I used the same setting for all photos, replacing the lenses I put before the Teflon the only decent autofocus lens I have is my old 50D f1.8 the micro nikkor 60 D and the new 60 G are terrible, the micro 105 D doesn't work either, the new 105S I haven't tried. Probably the ideal is to do a new test with light 340 - 350 - 365 and see where the "blockage" is -

I'm grounded these days because of harsh winter conditions outside. Lots and lots of snow and temperatures that on occasion drop well below -30C. Add strong polar winds and you have the perfect recipe for a fatal asthma attack if I would be foolish enough to venture outside. Instead I was browsing some UV captures and was reminded of a nice DIY project completed a few years ago. Time to share the details. The basic assumption is that you have a UV-capable lens and would like it to be "longer". The lens in question might be a UV-Nikkor 105mm f/4.5, or any old 105/135mm lens with decent UV transmission. To the latter end I purchased some dirt cheap Petri 135mm f/3.5 lenses and with these came a Petri 2X teleconverter. In a flash of insight I realised the TC 2X easily could be rebuilt so as to fit my UV-Nikkor to make it a 210mm UV lens. That is, if the TC transmitted any useful amount of UV. A quick test with a Nemo torch indicated tons of UV passed through the TC. Not surprisingly as the opticals apparently is a simple 4 element design with almost uncoated glass inside. Building the TC was very simple. I just removed the optics and put it into a suitable short extension ring with F mount either side, since I was going to use the contraption on various F cameras. For those interested, the Nikon E2 or FC rings are perfect, but doubtless more options exist. I kept the mounting barrel for the TC so as to be able to relocate the elements back and forth to get infinity focus -- at first try the master lens + TC was badly off infinity. So that is the story. I got a "new" UV lens for approx. $5. Here is the finished TC, to which I added a bespoke CPU chip while I was fiddling around with the parts anyway. It sits in an FC ring, however the E2 ring would do equally well and wouldn't require adding a male F bayonet at its rear end (the FC ends in a C-mount). Front view, Rear view, show the internal focusing unit from the original Petri TC, plus the CPU contacts. Finally, UV-Nikkors with and without TC !! All of this would be of no use if the combination didn't work well for UV. The adorable harbinger of spring, Tussialgo farfara, comes to assist in resolving the question. First, the "native" UV-Nikkor on my modified Nikon D3200 camera with internal Baader-U filter. Daylight, just standard UV processing through Photo Ninja. Then, with the TC-2X added, same processing, (photos not taken on the same day, but conditions otherwise as similar as it gets in a field test) So, the TC works. With the TC, the final exposure is reduced by just a little more than 2 stops, so adding the TC incur about 1/3 EV additional light loss apart from the 2EV by the TC principle on its own. Building the TC took me about 1 hour, including some Dremel work to get parts to fit on the inside.

ORIGINAL DATE: 2021 August 29 UPDATE 1 Aug 2023. Removed UVR Optics NIR-Block because not strong enough at OD2 in some regions. Replaced with reccie for BG39. UPDATE: 22 May 2023. Added suggestion for finding Schott/Hoya UV dual bandpass glass now that UVIR*Optics has gone out of business. UPDATE: 22 May 2023. Added AndreaU MK II and UVBplus to Name Brand Filter list.\ UPDATE: 9 April 2024: Added warning about Tangsinuo not providing the filter thickness requested by the customer. This is a "Best" list for some basic gear. Be sure to see the 2nd post for the UV-pass filters. UVP and its Owner/Admins have no monetary affiliation with any vendor. UVP and its Owner/Admins are "gear neutral". Use what you love using! All links are for your information only and do not constitute a vendor recommendation. Search around for the best prices. The recommendations here are for basic beginner gear. Your needs might be more specific or more advanced. If so, please consult the Stickies and check recent forum discussions. Note that there are NO camera or lens recommendations!! Everybody including their 3rd cousin's brother-in-law's mother's best friend has an opinion about UV-capable lenses and cameras and those opinions are all different. Try this search tag to find recent forum discussions: Camera Search Tag. In reflected UV photography, just as in Visible photography, we can say that better sensors do give better files. However, artistry in UV photography can be accomplished with any UV gear. SHOPPING WARNING: If you find some name-brand gear online at a price which seems too good to be true, then it is probably some imitation being passed off as authentic. Please shop only at a reputable online store. As one example, Alibaba was recently selling fake Zeiss T* UV-blocking filters. SAFETY Best UV Protection Glasses or Goggles: Yes, UV light is dangerous! Ever gotten a sunburn? Ever had snow-blindness? And UV damage to eyes & skin is cumulative. Look for at least 99% blockage and wrap-around protection in the safety glasses you choose. Here are two options. McMaster-Carr 99.9% UV Protection Rating The linked page shows wraparounds, panoramics which fit around the temple, and ventilated goggles. Prices range from $9 to $30. Here is a specific link for yellow or orange tinted goggles: https://www.mcmaster.com/eye-protectors/lens-color~yellow/lens-color~orange/uv-protection-rating~99-0-/ Here is a specific link for ventilated goggles: https://www.mcmaster.com/eye-protectors/lens-color~yellow/lens-color~orange/uv-protection-rating~99-0-/lens-style~panoramic/lens-properties~ventilated/ UVEX also makes very good protective glasses/goggles. The link is to the manufacturer's website which has scads of info about sports & safety glasses. To buy UVEX goggles it's probably best to google around for the best deal on Amazon or other websites. LIGHTING Best UV Illumination: SUNLIGHT !! "-) There's more UV in Sunlight at high altitudes. There's more UV in Sunlight in the middle of the day. There's more UV in Sunlight in summer. So, mountain top at high noon in July and you're good to go! However, if Sunlight is missing at sea level in the early morning in December, then see the next entry. Next Best UV Illumination: UV-Flash The Xenon flash tube must be uncoated. The Canon 199A is a current UVP favorite for modding into a UV-flash. But there are other possibilities. Use the next link. Lighting TAG Search Click that lighting tag search for further info about UV lighting. There will be info about UV-flashes in there somewhere. Ordinary Xenon flashes can be modified (DIY) with filters to pass only UV light. **WARNING** Please remember that flash units have murderous capacitors, so do not fry yourself dead by wonking around in the wrong part of the flash unit while changing the filtration. Mod a flash unit at your own risk!! Best Basic 365-nm UV-Led Torch: Convoy S2+ UV with Nichia Chip A NOTE: Recently the no-name "Nemo" torch has been more popular with the UVP Membership. Nemo search on UVP. Nemo search on Google. A UV-Led torch is used to supply light for focus illumination on the subject while focusing through Live View, or inducing Visible or IR fluorescence in a dark room, or light-painting a reflected UV subject during a long exposure. In the past Nichia was considered the best 365nm UV-Led Chip maker. But I don't think you should worry too much about either the brand or the grade of UV-Led chip because we are looking mostly for enough output (wattage). You might need two torches depending on how you make use of them. If you can find info about the UV-Led torch chip you are considering buying, look for an A grade UV-Led for best results. TORCH NOTE 1: The Convoy S2+ Nichia A torches are well-made, well regarded and meet stated specifications. If you want something less expensive, then you can take your chances with the unbranded UV torches sold on Ebay. Many of these do not meet their stated specifications. Please check the recent forum discussions for advice on unbranded torches! TORCH NOTE 2: That third use of a UV torch there in the bullet list? Let me point out the following: it's not easy to make a reflected UV photograph using only a UV torch. Exposures are long and results are noisy. The best reflected UV photos are made in strong sunlight or using a Xenon flash with a UV-pass filter. Sunlight and UV-flash produce more false color due to the wider range of UV. Best UV Light for Beginners, Intermediates and Advanced: UVA and UVB ONLY!! As for UVC, we say NO, just NO. UVC is too dangerous. And it is very difficult to find the filters, lenses and cameras which can record below 300 nm. There's scarcely any UVC light in sunlight anyway. So where would you find illumination? You don't want to even go near those 254 nm sanitizing bulbs which will break your DNA. Frankly, IMHO, what I've seen so far in UVC photography is not particularly impressive anyway. UVC is not where the beauty of reflected UV photography lies. It just isn't. If you must play with UVC, please remember that you have been warned by UltravioletPhotography.com NOT to do this. UltravioletPhotography.com cannot and will not accept any liability for damages you may incur from UVC light. Best Filter for Basic 365-nm UV-Led Torch: Hoya U-340 x 2.0 mm LINK to Transmission Chart LEDs have a fairly narrow output, but using this filter on your torch will ensure there is no violet/blue visible contamination when the torch is being used for inducing visible fluorescence. You do not need to filter your torch for non-fluorescent work. FILTERS Best UV/IR-Blocker for making Visible Light photos with Full-Spectrum Camera There will be opportunities to use your full-spectrum conversion in visible light. So replacing the removed internal UV/IR blocking will be necessary. Kolari Hot Mirror Pro 2 Best, IMHO. Link to UV/IR-Blocker tests Kolari's newest UV/IR-Blocker has a transmission curve which matches the transmission curves of most cameras internal filtration. White balance in-camera should give you good color. Any small deviations are easily tweaked in an app or by using a color correction profile. OR Schott BG38 x 2.0mm OR B+W 038 + [Longpass UV-Blocker] Filter stacks like this are somewhat more prone to flare & ghosting in backlit scenarios. Your choices for the longpass UV-Blocking component are: Schott GG400 or Schott GG420 Most camera makers' internal UV-cut filtration begins somewhere between 400-420 nm. Filter stacks work better if one of the components has AR-coating. That costs more though. Zeiss T* UV Filter This filter is regarded by many as the best UV blocker. It is AR-coated and cuts UV very well starting between 400-410 nm. Best IR-Blocker for making Reflected-UV photos with Full-Spectrum Camera Stack one of these over your UV-pass filter for extra protection against IR contamination. Schott S8612 x 2.0 mm LINK to IR-Blocker Transmission Charts for 2.0 mm Depending on the thickness of your dual bandpass filter, you might find that a thinner S8612 will suffice. But a 2.0 is almost universally useful and is the best thickness for your first purchase. Try to get one with AR coating. Recently S8612 has been difficult to find. OR Schott BG39 x 2.0 mm OR B+W 039 S8612 has become difficult to find, so look for this next best IR-blocker for working in UV with a full-spectrum camera. Best Chinese ZWB and Other Filters: Tangsinuo Technology This currently reputable vendor recommendation is subject to change. UPDATE 9 April 2024: Recently a UVP member has reported that the thicknesses of filters received from Tangsinuo have not matched the requested thicknesses in the order. For example, one filter was .5 mm thinner than requested. Please INSIST when ordering that your requested thickness is supplied or else you will give Tangsinuo a bad review and file a complaint with Ebay. LINK to Review by JMC Please remember that Chinese manufacturing is not currently subject to the same standards which apply elsewhere. Striations, pits and visible leakage have been seen with some of the Ebay Chinese filter purchases. And some of the filters don't quite match the expected transmission in either peaks or rate. But these equivalents of UV dual bandpass filters and BG filters are very much less expensive than the high quality Schott or Hoya glass, so most beginners use Chinese filters to get started. FILTERS is continued in the next post.

This is a UV fluorescence image of Celeriac - Apium graveolens var. rapaceum (not my favourite vegetable!) just for fun really. Nice colours and pattern in the cut flesh! Technical details: Both images Nikon Z7 with 105mm micro Nikkor lens. UVF image light painted with NEMO torch (365nm) for 10 seconds at f/22

I have found a worthy challenger to the Convoy S2+ based on a 15W 4-chip LED. https://www.ebay.co....ch/233620900023 The torch is wisely powered with a thicker 26650 cell instead of the 18650-cell used in the Convoy. That makes it easier to get a battery with high capacity and a low internal serial resistance. That is important as the torch use more current. I will buy more quality batteries for these torches as the included ones had a rather high internal serial resistance. Here is a link to the test of how different battery voltage affect the input power: https://www.ultravio...dpost__p__38385 It is important to realize that after the current curve becomes flat above 3.8V input voltage there is no increase in optical power. Above 3.8V the additional power is only heating the drivers. The torch's mechanical design and build is good. It has ring-shaped cooling finns around the front part to improve the cooling of the LED. There is a 2mm thick Ø40.9mm UV-pass filter that likely is a ZWB2 glass. In front of the filter there is a fluorescing rubber ring that helps to show when the torch is on. For UVIF photography that can be placed behind the filter glass, to not be visible. replaced with an o-ring of suitable dimensions. The connecting parts in the front and rear modules appear to be well designed and assembled. The front part has a metallic reflector that easily can be removed. The entire set of parts in front of the LED can be accessed and rearranged by unscrewing the front ring by hand. The LED chip is mounted on a 20mm star-shaped copper based PCB that is thermally coupled to glued with thermal glue the anodised aluminium-structure with thermal paste of some kind. The PCB is pushed against the aluminium structure and kept in place by the reflector, green rubber ring and front ring. Be careful, if the reflector is removed, to not lose the thermal connection between LED and aluminium body. Surface tension and capillary forces will normally keep the LED in place, but it can be pushed sideways and eventually get some air in between. The LED seams to be of good quality with nice wavelength distribution. The wavelength-peak (blue) is more narrow than the one in the comparison Convoy (red) and with the peak almost 1nm closer to the nominal 365nm. Without the filters the remaining light at 400nm is ca 1/1000 of the peak at 365nm. I made an intensity comparison with both flashes on side by side at ca 45cm from a sheet of paper containing fluorescent whitener. This image shows the two different hotspots created by the reflectors and it is quite clear that the Convoy is less powerful: With the reflector removed a very nice and even illumination can be obtained spreading cone-like as it is shielded by the front walls of the torch. When I tested the torch for adjusting the focus with a U-360 stack, illuminating the motif was much easier than with the small spot of the Convoy, No careful aiming was needed.

cucumber section of approximately 1 mm Sony A7 standard with Nikon L39 UV filter on the left with side light on the right with light from under the glass . Sony A7 full spectrum with Nikon L39 UV filter . Sony A7 full spectrum with yellow filter . Sony A7 full spectrum with green filter . Sony A7 full spectrum with Hoya R72 filter .

Makes sense...thanks for the explanation. Wouldn't this conversion be fairly inefficient? Seems like this wouldn't put out near the light of a Nemo. Still, interesting technology and it would be useful, for previewing a subject, to decide which dedicated light source to use. Thanks, Doug A

Some time ago I bought an Alonefire H45 UV torch that turned out to be defect. I filed a Dispute at Aliexpress and got a rather substantial refund while allowed to keep the torch. I wanted to open it up to learn more how it was designed and why it failed and had a small hope of a possible repair. This is topic is about the trouble it have and what I found out taking it appart. The problem: My H45 overheats and fades very quickly when turned on. A proper intensity fading comparison between the H45, the Nemo and the Convoy S2+ give this result: All three torches had fully charged batteries and a measurement from the integrating sphere was taken every 3s. during 3min. After ca 1 1/2 min the H45 stabilises at the low intensity level without fading anymore. As the light pattern of the H45 is much wider than the pattern from Nemo the actual intensity appears much weaker from the H45 after a while. The rate of the fading is also slow enough to make the eyes adapt to the fluorescence light making a visual judgement very difficult. I measured the chip temperature at the end and it was over 160°C. This has led to a partial fail of one of the LEDs and a slight beginning of failing of another. The light from the three LEDs now differ with the failing one emitting less UV and a bit longer wavelengths. Overheating a LED way beyond its Maximum Rated Temperature is not a good idea. The problem with my H45 is not due to a lower selection grade of LEDs, but due to bad thermal design and assembly. Exactly as aphalo wrote "I think it is impossible that a torch this size can dissipate even 15W without quickly getting hot." The dissection: The Lamp head is opened by unscrewing the ring, holding the main PCB: It has oddly placed tool holes, but was not very tightly locked. The PCB can then be wiggled out by angling it to get the USB-C connector free from it's opening. After removing the front ring, UV-Pass filter and a silicone O-ring the LED cooling block can be unscrewed forward. Observe the threads on the block and inside the housing. Here was the main problem with my torch. The block was not tightened at all. Due to a very loose fit there was almost no direct thermal connection to the outer housing. Even when tightened the thermal contact area in such a thread is rather small. This is a design flaw. The thickness of the block together with the LED's copper based PCB are reasonably thick, more than 6mm and reasonably OK. There were sufficiently with thermal paste between the PCB and the Aluminum block. The PCB was secured against the block by the reflector that was held in place with the central screw. The three LEDs are connected in parallell and also have their four chips in parallell. They should be driven with constant current getting a forward voltage around 3.7V The Electronics: The main PCB have three functional blocks beside the switch and indicating LEDs. I have not seen any sign of a constant current control for the LEDs. The only thing that limits the current is the row of resistors by the red cable where two has been removed. The current is defined by the voltage of the batteries and the voltage over the LEDs and serial resistances in resistors, cables and contact points to the batteries. This is extremely primitive! The function of the board is controlled by a small 8-pin processor at bottom right, above the six resistor positions in a row. The battery charging is reasonably advanced with a switch mode charger circuit. The processor controls two 13A Mos-FETs to turn the UV on and off and likely by pulsing for the lower light position. Interestingly there is plenty of room between the cooling block and the main PCB. There would be enough room for a constant current controlled driver,. Then ideally the UV-LEDs should be connecter in series to get a bigger difference between the LED driving voltage and the battery voltage. Such a design would be more costly.

1.) I had mixed up rows and columns, is correct now 2.) @photoni: the exposures given in the first post are readings from PS, I Assume RawDigger has rounded the 0.8 s to 1/1 3.) no dandelions around yet (still hibernating) The plant shown is a dried one from 2 years ago, which usually shows the bull's eye pattern, it was a test whether the pattern would show up still when dried, obviously the pattern is gone (though it still looks bright yellow, last year, the pattern was still visible) 4.) @dabateman: just did a very quick test with a Nemo with coverglass (blocking visible and IR) and still the Baader U seems faster than the SLOAN 5.) @photoni: yes, teflon might be better for WB, but for the comparison here that does not matter. Now (with the correct rows and columns) you can see from the first and second row e.g. that the Baader U , looked at with the WB form the SLOAN, is more blue-ish, what corresponds with the results from RawDigger.

I recently had to put an order in with Thorlabs and while I was there, I thought I'd try out another one of their lenses for UV photography - a 79mm UV fused silica aspheric (https://www.thorlabs.com/thorproduct.cfm?partnumber=ASL10142M). In the past I've played around with some of their 40mm lenses in a setup built from their parts, but I got a lot of distortion at the image edge with that (not a big surprise). See here for the thread on that - https://www.ultravioletphotography.com/content/index.php/topic/3754-back-to-basics-40mm-singlet-lens-from-thorlabs/page__view__findpost__p__33674 Moving to a longer focal length and an aspheric lens design, I hoped would help get some of the distortions under control and make the lens more usable. Here's the lens. And mounted on the camera using a range of parts. The weather here is dull and rainy today, but I went out and tried to get a photo anyway, taking a Nemo UV torch with me to boost the 365nm UV a bit. Baader U filter used and whitebalanced in Darktable. This the full frame image from the A7III, just with some denoising and contrast boosting done, with the lens stopped down about half way (I guess about f8). Resized for sharing obviously. And a crop from the original, kept at the original image resolution. The Buttercup photo was done at ISO6400 and 1/15s with a mix of daylight (no sun) and Nemo 365nm UV torch. Overall, I'm quite impressed with this little singlet. I'll hopefully do more with it when the sun comes out, but I also want to try it for UVB (or even UVC) imaging.

You don't like my punny nickname for it? Nemo is just Latin for "no name" (which was the situation when we first found it). It does look to me like the Nemo (or whatever it's real name was) spreads the light a bunch more. Keep in mind that if you double the spot diameter with all else the same, the irradiance will go down by a factor of 4 (since it depends on the area). So it's rather sensitive to the diameter. This is why we really need one of those integrating spheres to collect all the light.

Does anybody know where I can get one of these Nemo lights in Dec 2023? I mean the one Ulf describes with constant current ICs to help keep output levels steady. I was leaning toward getting a Convoy S2+ or S21- model, as I don't have any 26650 batteries, but do have 18650s and 21700s. But the higher output of the Nemo has me reconsidering.

Castellani A. (2024) Lilium sp. L. (Liliaceae) Asiatic Hybrid Lily. Flowers photographed in ultraviolet and visible light. LINK Italia 30 Jan 2024 Commercial Cultivar Comment: I bought this potted flower at the supermarket instead of a classic tulip bouquet. I was hoping to see a double yellow-blue signature like in Birna's photos LINK. Reference: 1. Wikipedia (acc 30 Jan 2024) Lilium I did some tests with the SoligorKA 35 f:3.5 - @f/11 and Sony A7 full spectrum. These were taken on a hazy day, with the sun barely visible... I imagine there is little UVA . Visible with QB39 1.5mm t filter. . Ultraviolet with TSN575+ZWB2. . Visible made in the studio with artificial light with QB39 1.5mm t filter. . Visible made with flash light (clear Pyrex tube). . UV made with TSN575+ZWB2. . UV made with Nemo 365 nm UV-led light. .

Been absent for a while (holiday and away from the microscope as a result) but here's a new image from the microscope taken using 365nm light. A Navicula of some type. Olympus BHB microscope using 365nm LED light (Nemo torch). 63x Leitz Pl Apo NA 1.40 objective with oil immersion. Olympus Abbe condenser, oil immersion. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Single image, no stacking. The slide is a diatom strew by John Dale, where a thin layer of aluminium has been deposited over the diatoms to help with contrast, hence the image looking like a dark field one. The image has been reduced is size for sharing. Going in tighter and cropping the image, shows the areolae with a spacing of 261nm as measured with ImageJ. A hint of the pores in the areolae is also there, but not well resolved. I also did an image of the same diatom with 450nm light (below). Shows the improvement in resolution when using 365nm light.

this is with "Nemo" 365 nm light + QB39 + Nikon L39 antiUV . .

Unfortunately the new 6-LED version is not an improvement over the Alonfire H42. The optical output from the "120W" torch starts at a slightly higher level ca 10-15% above the "H42" torch, so what we see is just an even more inflated false marketing specification. Both torches drop in intensity and reach a rather low steady state after ca 4 minutes. The "120W" six LED version drops faster and level out at a lower level rather much lower than a Nemo-Torch. The faster drop rate indicates a less efficient thermal transfer of the losses. The "120W" LEDs also have a peak closer to 370nm so more UV will be blocked by the ZWB2-filter that will be more heated.

I think I used the Nemo torch, or some other filtered 365nm LED lightsource. The photos differ quite a lot from what the things looked like in real life. I enhanced the colors to highlight subtle color differences. Both images are high res so feel free to enlarge them.

The Nemo flashlights arrived. Their special filters look similar to a ZWB1. What camera filters are they comparable to? When using the torches with supplied filter, is an UV filter still required on the camera lens? If so, can the UV filter be added to the flashlight? I walked around outside in the dark with a torch and found some nice subjects. So glad there aren't neighbors to explain the goggles and weird light to. Thanks, Doug A

Firstly, Merry Christmas everyone. A single image from an 'Amician test slide' by Watson and Sons (no stacking with this one). Navicula rhomboides, used for testing resolution. Done on my modified Olympus BHB microscope, using 365nm light (Nemo torch). 100x Leitz Pl Apo NA 1.32-0.60 objective, oil immersion. Reichert Neo 1.42/1.18 dark ground condenser, oil immersion. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Reduced in resolution for sharing here (original image size 6136x5540). Dots are about 360nm apart.

After some searching I found the exact model as a branded Alonfire SV13. https://vi.aliexpress.com/item/4001165789043 Before there were several sellers of the Nwemo type. I am quite confident that this is the same model as the tested Nemo. It is a bit more expensive than a S2+, but the SV13 includes the needed VIS-blocking filter. All S2+ I can find are lacking that filter, that you have to source separately. There are some 365nm S2 with filters. You can normally run a torch for 26650 with a 18650 if you get a cheap plastic adapter tube that gives the 26mm diameter outside the 18650. I think the kit with the 26650 battery is a god alternative if you want to get a battery too. If you do not already have a universal battery charger I can tell you that I am very happy with my Miboxer chargers. The most advanced is the C4-12 that I have https://vi.aliexpress.com/w/wholesale-miboxer-charger-c4%25252d12.html There have been several other models of the C4 and I also have a C4+. Cannot find that model anymore, only the C4. https://vi.aliexpress.com/item/32843228093.html It is more compact as the AC PSU is built in, while the powerful C4-12 needs an external power supply brick. I have had several models of MiBoxer chargers and always been happy with their performance. The older ones have been given away or on loan to friends, when I upgraded to later models. Yes, I have more chargers than I need! ;-)

The spot is not much smaller then the supposed named Nemo which is has 4 emitters & a softer circle.

@moondigger There is a new light on the market, it is by an Australian seller & has an Irradiance output of 36mW/cm2. The so called Nemo has 12mW/cm2. https://fluoromins.com.au/opal-hunters-365nm-torch/fluoromins-f8-365nm-torch/ Here are my tests..... 36mW/cm2 at 380mm distance, which is the industry standard distance for UV LEDs. The bright spot is 63mm at a distance of 380mm.

The latest development for UV-torches with this mechanical housing style is by adding 3 more quad LED arrays to a total of 6. They have gone from a marketing power of "45W" to "120W". https://vi.aliexpress.com/item/1005006137265886.html As there is no added externa cooling surfaces or fans so here cannot be an input power anywhere near 120W. It might have different internal drive electronics for the LEDs. Beside the one defect torch I analysed above I got a second one that is working well. It too is fading when heating up. Still it is my most powerful UV-torch and I like it even if it is fading. When I use it for shorter periods, less than 3 minutes and then it is more powerful than the stable "Nemo" style torch. I fell for the temptation and ordered one "120W torch, to measure and compare the emitted intensity with my "45W" With some luck distributing the generated heat over six LED arrays the losses might be transferred more efficiently to the case making it a bit brighter for a longer operation period.

I've finally got around to testing the new (Nemo ?) torch against my Convoy. In the examples shown, the Nemo is in the centre, and Convoy on the right. All UVF exposures 10 seconds @ f/16, light painted. Because the subject is relatively small in relation to the torch I suspect the narrower beam of the Convoy compensates for the lower power. I will try to do some more using a more scientific approach! Subjects are Rudbeckia "Marmalade" and Gazania (unknown variety) Camera: Nikon D850 with 105mm micro Nikkor. 200 ISO

The new 'no name', AKA 'Nemo' torch, introduced here first by Ulf: https://www.ultravio...dpost__p__37933 Does anyone know the actual LED used in the 'Nemo' torch? Here are some comparisons I did between the Nemo and Convoy S2+ Nichia torches. All things being equal, with fully charged batteries. Beam comparison. Distance is 3.75" (95mm). Reflectors in place. BLAK-RAY UV Meter test, distance is 3" (76mm), no filter. Reflectors in place. BLAK-RAY UV Meter test, distance is 3" (76mm), with Hoya U-340 2mm filter. Reflectors in place.