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Author's Statement for Transparency and Disclosure
The test sample/s featured in this article were provided for technical testing and review by "Fenixlight Limited". Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.
Supply and Delivery was fulfilled by "MyFenix.co.uk", the UK Distributor for Fenix lights
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Author's Statement for Transparency and Disclosure
The test sample/s featured in this article were provided for technical testing and review by "Fenixlight Limited". Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.
Supply and Delivery was fulfilled by "MyFenix.co.uk", the UK Distributor for Fenix lights
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Fenix have had great success in the compact 2x18650 category with the TK35 and TK35UE. Now, in the LD50, Fenix have created another winning formula, taking the class to another high and making the form factor even more compact.
Author's note: many of the images used in this review are animated to reduce excessive scrolling. You may need to wait for the images to load fully.
Taking a more detailed look:
The photos here show; the packaging, contents, top view, bottom view, side view (showing ultra slim profile), switch, looking through the LD50, lens and reflector, LEDs, one tail-cap removed, internal contact, both tail-caps removed with 2 x ARB-L2S 3400mAh 18650 cells, the LD50 with Fenix ARE-C2 smart charger, and a personalised NW20 whistle (laser engraved by MyFenix).
Moving onto the LD50's holster to show the fittings on the back as well as the front view:
And now for a quick spin around the LD50.
The beam
The LD50's beam is lovely and smooth, and the power belies its compact size.
On the edges of the indoor beamshot you can see the double shadows due to fact that the LD50 has two separate emitter/reflectors. You will notice this from time to time but in general use but it isn't a problem. The hotspot is wide and even, and for me, Fenix have hit the sweet spot here between throw and flood and created an excellent general purpose beam.
Outdoors the LD50's 1800lms wash away the darkness and the wide beam fills the area with light.
For such a simple head design, the LD50 achieves a wonderful beam, and its power gives it plenty of reach.
Modes and User Interface:
With a single electric click switch, Fenix have given the LD50 a reasonably simple interface.
From OFF, press and hold for the switch for 0.5s to turn on to the last used constant mode.
When ON press the switch briefly to cycle through ECO, LOW, MID, HIGH, TURBO back to ECO etc.
To switch OFF, while the LD50 is in a steady mode, press and hold the switch for 0.5s.
The LD50 has direct access to STROBE from either OFF or ON:
From ON, press and hold the switch for 1s to activate strobe. To return to the previous ON mode press the switch briefly. NOTE: When starting from ON, once STROBE is activated, the LD50 will not switch OFF without first being returned to a steady mode. Like this, with STROBE active, pressing and holding the switch does nothing.
From OFF, press and hold the switch for 1s (at 0.5s you will see the steady mode activate, but just keep holding it), and STROBE will activate. To switch the LD50 OFF, press the switch briefly. It is only when starting from OFF, that the LD50 can go from STROBE to OFF quickly in this way.
The test sample I have differs from the instruction manual in that the instructions state that when activating STROBE from OFF, that once you let go of the switch, it will turn OFF. For this sample, this was not the case, with the operation being as described above.
Batteries and output:
The LD50 has a trick up its dual battery tube sleeve. Unlike just about every other 2 x 18650 light, the LD50 can happily run on only one. Of course this translates to the CR123 use as well, as fully loaded the LD50 used 4 x CR123 (Not RCR123), and can also run on only 2x CR123.
It does this by virtue of the parallel configuration of the battery tubes, so that the LD50 is running on either 4.2V or 6V depending on the choice of Li-ion or Primary cells. This means that it can indeed run with only one battery tube filled.
The LD50 effectively operates as if it were two separate lights fused together and controlled with a single switch. This is even more evident, as if you do only load up one battery tube, only that LED in front of that tube will light up.
This feature makes the LD50 incredibly versatile, as if you only have one spare 18650, or set of two CR123s, no problem, just load that up and carry on. The only consequence of this is that the output is halved. A very sensible approach, as instead of driving both LEDs and making the cell/s struggle, the LD50 drives the single LED exactly as it would as if both battery tubes were filled, and both LEDs were running.
Keeping this test as 'FENIX' as possible, the LD50 was powered using ARB-L2S cells charged with the ARE-C2 multi-chemistry charger.
To measure actual output, I built an integrating sphere. See here for more detail. The sensor registers visible light only (so Infra-Red and Ultra-Violet will not be measured).
Please note, all quoted lumen figures are from a DIY integrating sphere, and according to ANSI standards. Although every effort is made to give as accurate a result as possible, they should be taken as an estimate only. The results can be used to compare outputs in this review and others I have published.
| LD50 using Fenix ARB-L2S 3400mAh cells | I.S. measured ANSI output Lumens | PWM frequency or Strobe frequency (Hz) |
|---|---|---|
| Turbo | 1868 | 0 |
| High | 790 | 0 |
| Medium | 344 | 0 |
| Low | 142 | 0 |
| Eco | 25 | 0 |
Strobe frequency rotates between 6.8Hz and 16.6Hz
As there is an electronic switch we need to consider the parasitic drain. The Fenix LD50 has the lowest drain I have yet measured, a really outstanding result for Fenix and the LD50.
There is an interesting feature of the drain, in that for a single 18650 cell, the drain is 1.7uA (which is outstanding as it is), but with two cells, the combined drain is lower still, at a total of 0.9uA! This is only 0.45uA per cell.
At these levels of drain, with only a single cell the LD50 would take 228 years to deplete the cell, but with two cells fitted, it would take 861 years to deplete the cells!
The LD50 runtime trace was carried out using 2x 3400mAh ARB-L2S 18650 cells, and the Turbo output was reset every 10 minutes when it dropped out of Turbo. During the runtime test, the head reached 56 Degrees Celsius with a cooling fan running.
Summing up
There are lights which come along and are striking in some way or other, standing out from the rest. For me the LD50 is definitely one of these.
It just looks different, from the flat slab like shape, to the holes milled through between the two battery tubes allowing you to see straight through it. This shape feels great in the hand, and your thumb falls comfortably onto the power switch. In this case the twin emitter design has a true purpose, in that you can run only one or the other based on which tube has a cell in it.
Despite housing two 18650s, the LD50 is very compact, and makes the TK35 (which is itself a compact design) feel large by comparison.
By using 2 x 18650 to power the LD50, you really do get nearly 2000lm of output. At this level of brightness you are not left wanting more.
With a very refined beam profile the LD50 will work just as well indoors, as it will outdoors. Of course it is outdoors that you can really let rip with this light and appreciate its power.
Indoors, the LD50 is super stable when placed flat on a surface, or standing on the twin tail-caps for room lighting ceiling bounce. This is one light that will NEVER roll away!
Although I would prefer the LD50 if it had a super low output, and perhaps a different interface with two buttons, there is nothing about it that I actually dislike, in fact I like just about everything about it.
With a distinctive shape and styling, flexible power options, very bright 1800lm output, compact design, ultra-low drain and comfortable shape to hold, the LD50 is a light I am finding very hard to put down. I just keep picking it up to handle it, put it down and then find myself reaching for it again.
The LD50 certainly ticks all the right boxes for me, and presses all my buttons. I can't leave it alone.
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