I have happily been using and recommending the Convoy S2+ 365 nm UV flashlight since early 2017 when Mark Cole first posted about it. It is a fantastic product, small and powerful and cheap. However, it is a little too small and I found myself putting it down and forgetting to pick it back up enough times that I decided to buy more lights. Since I was at it, I figured I would buy some of the new lights from other manufacturers as well to see how they compared to the original gold standard.
I hoped to test the lights objectively and post something in time for Christmas. Unfortunately, I haven't had time to put together an article until now, and I haven't done as much testing as I would have liked. After the new year, I will do some more testing and add it to this post.
To test the lights, I searched for an appropriate target that would give a sense of the width and intensity of the beam. I thought I would need to design something new, but I found a roll up magnetic dart board that worked well. I also searched for a way to hold the lights so that they did not move and were all a uniform distance from the target. For this purpose, I found an old stand that was designed to hold a reflector umbrella for photography. The testing setup looks like this:
The front of the light was placed about 8.5 inches from the target - the exact distance needed for the Convoy S2+ to completely light up the circles on the target. The camera was placed to the side and put in manual mode with ISO 200 and 3 second exposures and the lens was set to f/22. The target works well, as you will see, but it doesn't truly represent how rocks respond to the different levels of UV light. All lights are filtered unless I say otherwise. Despite all this testing and attempt at rigor, my conclusions are still subjective based on observations of a single light and a single photo.
The Convoy S2+ is the first affordable 365 nm UV flashlight. It uses a Nichia 365 nm LED and is powered by an 18650 rechargeable battery. Before it there were plenty of junky UV LEDs that might charitably have been called 395 nm. You can find lots of these on the internet. They generally have many LEDs, they are cheap and they don't work very well. There also were some very good, very expensive flashlights produced by Raymond Wu and Michael Isaacson. The Convoy S2+ was simply much cheaper than the existing good lights and much better than the existing cheap lights. For everything you can possibly want to know about the Convoy S2+ and more, check out Mark Cole's review.
Here are pictures of the S2+ with and without a filter. The pictures are a bit deceiving. The exposure was chosen to not overexpose the central dot for the filtered Convoy S2+. This causes the outer ring to look darker than it really appears in person. Suffice to say, if something is visible in the image, UV is there. The unfiltered light shows a bit more UV response, plus the color shift that you would expect from an unfiltered light.
The Convoy S2+ can be found cheaply, and probably without a filter, from various Chinese sites. It has also been rebranded as the Way Too Cool Torcia which is sold by various American dealers. If you pay more than $30 for the light or $60 for a kit with a light, filter, battery and charger, you are paying too much.
In 2018 the maker of the Convoy S2+ came out with a UV version of the Convoy S2. This is a slightly longer light that uses an LG LED and is typically shipped with a filter and a smooth reflector. Theoretically, this is a slightly more powerful light than the S2+, but there is no practical advantage that I can see. The smooth reflector causes the center of the beam to be slightly darker than the brightest part of the beam and, overall, the beam is narrower than the S2+. It is fine for finding fluorescent minerals. It is not as good for taking pictures of them. These pictures show the beams with the stock smooth reflector and with a separately installed orange peel reflector that blurs the beam and eliminated the dark spot in the middle. The dark spot is not evident in these pictures... but even without it, I prefer the OP reflector image.
The Convoy S2 can be found on various Chinese websites. It is priced similarly to the Convoy S2+, though it is often found on sale for a cheaper price.
LightFE is a flashlight company that seems to be getting into the UV light category in a big way. They currently have 4 different 365 nm LED lights available, plus a couple more 395 nm lights. The biggest difference between LightFE and most of the other lights (that I have tested) is that you can buy them using Amazon Prime and get them in a couple of days as opposed to getting them on the slow boat from China. The other big difference is that 3 of their UV lights do not use the 18650 battery. That battery is a beast - it can hold a large charge and lasts a long time. However, it can also be expensive and requires you to have a charger. LightFE has lights that run on AA or AAA batteries.
LightFE UV302 365nm
This is the big daddy of LightFEs offerings. It is a larger filtered light that has three different power levels. It is more expensive than the various Convoys from China, because it ships with a charger, carrying case, battery, charger and safety glasses. The battery is even a high quality Samsung battery. This light seems slightly brighter than the Convoy, but it is also larger, heavier and more annoying. I say annoying because of the three power levels. As far as I can tell, it just cycles through the power levels. You cannot get it to always turn on on the high level, so you have to cycle through the levels to find the level you want.