Review: Fenix TK15C White/Red/Green (1x18650, 2x CR123)


Flashlight Enthusiast
May 5, 2010
Hove, UK
Author's Statement for Transparency and Disclosure
The test sample/s featured in this article have been provided for technical testing and review by the manufacturer. Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.

All output figures and test results published in this review are the sole work of the reviewer, and are carried out independently and without bias. Test results are reported as found, with no embellishments or alteration. Though best endeavours are made to maintain the accuracy of test equipment, the accuracy of these results is not guaranteed and is subject to the test equipment functioning correctly.

Many multi-colour lights add secondary colours as more of an after-thought and use token low output low power LEDs. Fenix have been looking at producing much stronger coloured output and the TK15C is one of these (LD75C is also on test at the moment).


Taking a more detailed look:

Fenix’s standard packaging.


Included with the TK15C are a holster, lanyard, spare switch boot, two O-rings and the instructions.


The TK15C fits into the holster bezel down.


On the holster are a fixed belt loop and small clip loop.


To get an idea of its size, the TK15C is next to a Fenix 18650, the ARB-L2S.


The switch is semi-protected, but also easily accessible, as the button does protrude but has some raised points round it to help prevent accidental activation.


The TK15C comes with a stainless steel clip fitted. The clip has been tumbled to remove any sharp edges.


There is a side mounted mode button.


A first view of the reflector assembly and three emitters.


The main white LED is an XP-G2 and the two coloured LEDs are Philips LUXEON Z LEDs.


The tail-cap has a spring for the negative terminal.


The tail-cap threads are fully anodised cleanly cut square threads.


It is possible to unscrew the head.


This gives a clear view of the positive contact spring and circular battery tube contact.


The head threads are different to the tail-cap threads, being more trapezoid. Again fully anodised and cleanly cut.


Just for reference here is the TK15C with the TK15 S2.


The beam

Please be careful not to judge tint based on images you see on a computer screen. Unless properly calibrated, the screen itself will change the perceived tint.
The indoor beamshot is intended to give an idea of the beam shape/quality rather than tint. All beamshots are taken using daylight white balance. The woodwork (stairs and skirting) are painted Farrow & Ball "Off-White", and the walls are a light sandy colour called 'String' again by Farrow & Ball. I don't actually have a 'white wall' in the house to use for this, and the wife won't have one!

To better show the appearance of the three beam colours, both the indoor and outdoor beam-shots are put into an animation with the same exposure and with the TK15C clamped into a fixed position.

As expected you will see the bias of the coloured beams to opposite sides of the white beam’s position. This is due to the LED’s position in the reflector.


Outdoors the coloured beam’s bias to each side is even more visible. As it the difference in brightness of the red and green LEDs.


Modes and User Interface:

The TK15C has five steady output modes, High, Medium, Low, Red, Green, and two flashing modes White Strobe and Red/Green strobe.

The tail-cap switch is a forward-clicky type giving momentary control.

With the TK15C ON, the mode is selected using the side button.

When ON, pressing the side button cycles through High -> Medium -> Low -> Red -> Green -> High…

To access flashing modes, with the TK15C ON press and hold the side button for 2s. This will change to White Strobe. Pressing the mode button changes to Red/Green Strobe. Pressing again give the White strobe.

To exit flashing modes either switch the TK15C OFF or press and hold the mode switch again for 2s.

In main mode, the last used steady output is remembered.

Batteries and output:

The TK15C runs on 1x18650 or 2x CR123 (RCR123 are not permitted).

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.

using I.S. measured ANSI output LumensPWM frequency or Strobe frequency (Hz)
White Strobe28915.6 and 6.7
Red/Green Strobe749.4

* Beacon and Strobe output measurements are only estimates as the brief flashes make it difficult to capture the actual output value.

Peak Beam intensity of the White beam measured 12000lx @1m giving a beam range of 219m.
Peak Beam intensity of the Red beam measured 200lx @1m giving a beam range of 28m.
Peak Beam intensity of the white beam measured 900lx @1m giving a beam range of 60m.

There is no parasitic drain.

Due to time constraints only the White runtime trace is shown.

After the normal sag during the first 20 minutes there is a steady decline in output until the TK15C drops to the Medium output level. This is then maintained for a further 4 hours.



This is a new section I am adding to mention any minor niggles I came across during testing, in case the information helps anyone else.

No issues were encountered during testing.

As per the description of this section, this information is provided in case anyone else finds a similar 'issue' that might be fixed in the same way.

The TK15C in use

The theory of the TK15C is to have access to strong coloured beams without using filters. Though this works well enough, with the coloured outputs being of respectable brightness, the issue with the coloured beams is that they are created by a compromised reflector. The resulting beams are full of artefacts and are not well focussed. At close ranges this is not really an issue, but starts to loose impact as the range extends.

The coloured beams do work well enough in a hunting environment over shorter ranges for lighting up the eyes of your quarry, however due to the artefacts in the beam it is not good for target identification, nor well suited to the view through a scope. For these you are better served with a dedicated coloured beam.

Instead the TK15C is more of a Swiss Army knife of a light as the white beam is perfectly good for gun mounting and illuminating the scope view, and you have the benefit of pretty reasonable coloured beams built in. This is where I see the TK15C’s strength. Don’t assume you are getting coloured beams anywhere near as good as a single colour light, but instead you are getting very capable secondary coloured beams, far better than other multi-colour lights.

I often move round my hunting land with a Red beam on as the quarry I hunt seem completely blind to Red. Once in position and ready for final shot preparations, I can switch to White, confirm the target and take the shot. No fiddling with filters or swapping lights.

As the red and green output are a fixed level, you can’t use these for preserving might vision as they are quite bright.

Just like the TK15, the TK15C is a relatively compact 1x18650 light so is easily accommodated onto any long gun.

Review Summary

Things I likeWhat doesn't work so well for me
Access to bright coloured beams with no filtersPoor beam quality of coloured beams
Strong main beamNeed to cycle through all levels to access colour
Relatively compact
Remote switch available
Separate mode switch




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lumen aeternum

Sep 29, 2012
The beam pattern of the red & green seems to be brighter in the corona than in the center. Is that what it really does, or is it a photographic artifact?

I have a red lens for my TK20 and its all central hotspot. Wish it was more uniformly floody.


Flashlight Enthusiast
May 5, 2010
Hove, UK
The beam pattern of the red & green seems to be brighter in the corona than in the center. Is that what it really does, or is it a photographic artifact?

I have a red lens for my TK20 and its all central hotspot. Wish it was more uniformly floody.

There is a hotspot, and this is the brightest part of the beam, but the artefacts do create bright areas in the spill. In the outdoor beam shots, the artefacts hitting the grass make it look like they are brighter than the hotspot, but of course, the hotspot is going further.

It is a bit of a mixed bag, as the white beam is great and the brightness of the red and green is very good (probably unmatched) for secondary LEDs.