This post was made over four years ago. Since that time it has become outdated. There is a new light - the Convoy FyrFly which is significantly brighter and a major next-generation of an already excellent light. Technology moves on; I hope to do a review on it at some point. (Mini review done: FyRFly - The Convoy Reimagined.
Until recently, the only LW lights collectors had to use (effectively) in the field were complicated and expensive battery powered fluorescent UV lights. Folks tried using the myriad array of cheap 390nm/395nm LED flashlights (often falsely advertised as 365nm), or similarly poor 4W/6W fluorescent blacklight toys, but were quickly disappointed by the low power (in spite of claims to the contrary) and overwhelming blue/purple light from these low-end products. This light is different.
Convoy S2+ 365nm Longwave Mineral Light
Links for the various components, the flashlight, etc. will be provided at the end of this blog article - Techy details, instructions to clean/replace the UV filter - scroll down.
Prices when this review was written were originally around $22 to $25 for the Convoy s2+. At that price it is an amazing performer. But the price has recently (2018) been artificially driven higher by domestic (USA) pressures; one China distributor has stopped shipping to the US altogether. But there are still several companies in China (Fasttech, Aliexpress, Banggood) offering filtered lights in the $20 to $30 price range. It uses a Nichia NCSU276A 365nm LED - one of the best, high-power UV LEDs on the market (2015). The LED is driven hard at 700ma for 3 watts of total power (500ma is the recommended drive current). It has a radiant UV output of around 1000mw (more/less depending on tolerances- driven @700ma, 25% overdriven), all emanating from a pinpoint light source. (A datasheet on this LED can be found here: https://www.nichia.co.jp/specification/products/led/NCSU276A-E.pdf).
Update: Three years after I made this blog post there have been dozens of copycat flashlights introduced to the market. Many claim "new and improved, higher power, 5 watts, etc.". Caveat emptor - this little flashlight and all like it are around 3 watts no matter what others claim - read all about it in this latest GlowNotes post.
Note: a few years after this writing (now 2018) new versions/competitors of the Convoy have been released with even higher power LEDs - some advertising up to 5/6 watts. This little flashlight is already on the edge when it comes to heat; consideration must be given to heat (see section below). A couple of new entrants from Jaxman include the following:
JAXMAN U1c focus spot 6W Nichia UV LED LAMPS 365nm - $63.00 for a kit including battery and charger, filter
JAXMAN U1 365nm 3W UV LED flashlight - $26, filtered (Convoy copycat)
NOTE: PRICE GOUGING! Price on these lights have been raised to over $100 in many cases - simply not worth the price, no better than the half-dozen or so other Convoy knock-offs. (as of mid-April, 2019)
Update #2: A new, significantly more powerful light has been introduced. Worth every penny if you're looking for a powerful, superb design with accurate power specifications: https://www.engeniousdesigns.com/product-page/fyrfly Simply the most powerful light in its category money can buy.
Using a single 18650 battery they provide hours of use on a single charge. The reflector focuses the UV output to an intense, but smooth "spot" and has a range of 10 meters or more, lighting specimens handily quite far away. The intensity of the beam even lights up rocks in daylight or under dealer lighting at shows. The dimensions are 118mm x 24.1mm, and it weighs 90 grams w/o the battery.
The Convoy S2 is available with and without a UV bandpass filter. All UV LEDs emit visible light, some more than others. The Nichia LED is known for being among the lowest offenders, having very little visible light output - but it's still quite noticeable. It is this visible light leakage that causes pictures of minerals to all have that terrible blue cast overwhelming most of the fluorescence when a cheapie light is used (or even a fluorescent BLB (blacklight). For use with fluorescent minerals a filter is an absolute must (this author's opinion).
Viewing minerals with this flashlight is a treat - it activates fluorescence in minerals not thought to be LW fluorescent. But without a filter the colors can appear washed out, or worse, a dimmer fluorescence might not even be noticed. A ZWB2 filter is an inexpensive piece of colored glass which performs as a longwave bandpass filter and is perfect for our application. Transmission specs for the ZWB filter line can be found on our Technical Specs page. As of 2018 several folks, both USA and China, sell assembled lights with filters, some even offer batteries and chargers in a kit. But eventually your filter might break/get scratched or simply need replacement. Luckily the replacement filters [visible blocking, UV passing - ZWB2 20mm round] sell for a very reasonable price ($1.50 to $10 - all the same, just different pricing).
The Convoy is the only light you will ever need to prospect for minerals in the field or at shows. The intense spot reveals fluorescence even in daytime light. But at home it's really not suitable for large home display cabinets - the small "spot" works against us, illuminating only a small area. For home displays an LED light configured as a floodlight is best. Check out this blog post for a neat 365nm LW display system perfect for small to extra large displays.
Batteries - the lights do not ship with a battery. It uses a standard 18650 lithium battery available almost anywhere fine batteries are sold. I use batteryspace.com almost exclusively as my battery supplier. I would choose a "protected" battery (prevents you from over-discharging the battery). Of course you will also need a charger. These batteries are used in almost all the major white-light LED flashlights now on the market - nothing terribly special. (links below)
A couple of large "mega-threads" developed in the FMS Fluorescent Mineral Discussion Group, with contributions by many folks. You can view them here: https://www.facebook.com/groups/fluorescentminerals/permalink/10154991367833571/ and https://www.facebook.com/groups/fluorescentminerals/permalink/10154964299628571/
A Brief Review of this Light's Performance and Technical Details
So why am I so excited about this light? This is a picture of a piece of Greenland sodalite taken with the room lights on (quite bright). The pen shows how far away the flashlight was from the specimen. Even at this distance the fluorescence was so bright that I had to cut back the exposure time on the camera. Light up your rocks in the daytime!