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ReviewTheLight: Fenix TK32 (950 Lumens + 100mW RGB Emitters) —by Bigmac_7, CPF

Publish Time:2014-07-28

Fenix is one of the leading names in high-end flashlights, and the've recently released the new TK32, an 18650 class for balanced throw of 900+ lumens and individual red, green and blue emitters.

Thanks to Fenix for providing the TK32 for review.

I’ll be reviewing the TK32 in two sections: first, I’ll discuss the light objectively (the facts about the light itself), then I’ll discuss the light subjectively (my impressions about the light's performance when used for specific applications). If you have any other specific applications you'd like the light tested for, let me know and I'll see what I can do.

Video Review
Below is a video review of the TK32. Due to my old image hosting site closing down, I've got new restrictions on image uploads and have replaced the "Construction" section of my reviews with a more detailed video review.


This video is available in 1080p HD, but defaults to a lower quality. To select the playback quality click the settings button (looks like a gear) after you've started the video.


Manufacturer's Specifications

Price: 95 USD

Product Manual


Plus, here's a few shots with some good detail.
(click to enlarge)

User Interface

The TK32 is controlled by two rear switches, the power switch and the mode switch. The power switch is a mechanical forward-clicky, and the mode switch seems to be an electronic switch. The power switch is the larger of the two, is a circle, and is raised to protrude farther that the mode switch. The mode switch is smaller, sits lower, and has an almost crescent moon shape. The TK32 has four regular white brightness modes and three color modes.

To turn the light on/off, you press the power switch. Pressing it half way will activate the light momentarily until you release, and pressing it all the way with click it into position so that it remains on until you press it again. This will turn the light on in the last white brightness mode you used (the color modes are not memorized). From there, you can cycle through the four brightness modes in the sequence Low -> Medium -> High -> Turbo. 

To activate the color modes, you turn the light on then hold down the mode button for about a second, and it will come on in the last color mode you used. Then, clicking the mode switch again will cycle through the color modes in the sequence Green -> Blue -> Red (each side emitter is a single color). Holding the mode switch again will take you back to the last white brightness mode you used. Alternately, when the light is off, you can hold down on the mode button and it will act as a momentary switch for the Red mode, leaving the Red emitter on until you release the mode button.

Something I discovered by accident but don't remember being in the manual: If you are using the momentary Red function by holding the mode button when the light had been off, then click the power button without releasing the mode button (not hard to do due to the switch layout, hence my finding it by accident), it switches to a constant Red function. You can then release the mode button and the Red mode will stay on, and will not change for any clicks or holds of the mode button, but will only turn off when you click the power button again. I'm not sure if this was intended (I'll have to check the manual or possibly ask Fenix) but I find it to be useful.

Action Shots

You can click on any of these shots to see them full size.
Light in Hand



White Wall
ISO 100, f/3.5, 1/20" 

White wall w/ increased exposure:

Indoor Shots
ISO 100, f/3.5, 1"

Outdoor Shots
ISO 100, f/3.5, 2.5"

And a few with higher exposure:

Long-Range Shots
ISO 100, f/3.5, 5"


Submersion: I submersed the TK32 under a foot of water for about an hour, clicking both switches several times. I found no evidence of water entering or damaging the light.

Heat: The TK32 gets hot after about 10 minutes on Turbo, but not uncomfortably so, then cools down when it automatically steps down output at 15 minutes.

PWM: I was able to detect very rapid PWM on the low modes of the TK32 using my camera, but it was not visible to the naked eye.

Drop: I dropped the TK32 from about a meter onto various surfaces (including grass, carpet, dirt, and hard wood), and found no cosmetic or functional damage.

Reverse Polarity Protection: Fenix claims reverse polarity protection for the TK32, so I tried inserting the batter backwards and clicking the switches. When I corrected the battery, it resumed normal function with no apparent damage.

Over-Discharge Protection: Fenix claims over discharge protection for the TK32, and I did find my battery not completely drained when the run was done. However, there are a series of stepdowns in output that will occur before that, which are a better cue to re-charge your battery before it gets very low.

Spectral Analysis

All light that we see as white is actually made up of several different colors put together. The relative intensities of the different colors in the mix are what determine the tint of the white we see. For example, cool white LED's have a lot of blue, and warm white LED's have more red or yellow. This measurement was done on a home made spectrometer. The plot below the picture is corrected for the spectral sensitivity of the human eye. Note: the peak in the 900nm region doesn't really exist, it's a piece of the second-order spectrum that's showing up here because of the high intensity of the light source. 

Output and Runtime

ANSI FL-1 runtime ratings are the time it takes for a light to fall to 10% of it's original output (counting from 30 seconds after turning the light on). 

The vertical axis of the graphs below represents a relative brightness measurement using a home made light box. The horizontal axis is time in hours:minutes:seconds. Runtimes are stated in hours:minutes:seconds. These graphs may be truncated to show detail.

Mode Comparison



Throwing Distance

ANSI FL-1 standard for stating a light's throwing distance is the distance at which the peak beam intensity (usually at the center of the beam) is 0.25 lux. I calculate throwing distance and candela (lux at 1 meter) by measuring peak beam intensity at five different distances and using the formula lux*distance^2=constant.

Subjective Review

Quick break down:

+ Higher brightness than claimed, very rare 
+ RGB output, also rare 
+ Excellent regulation
+ Good beam pattern at long distance
+ Good throw
+ Two-button user interface
+ No flashy modes
+ Momentary Red
+ Decent Low mode
+ Separate color mode memory

- Ringy beam pattern up close and for RGB emitters
- Each emitter only one color
- Rolls

So, the TK32 is a pretty unique light. There are very few high-end lights that utilize colored emitters, and even fewer that have max brightnesses higher than their claims . The TK32 uses three emitters on inner sides of the reflector, each with a different color, red, green, or blue. I've seen other lights with colored emitters where a single emitter can do multiple colors, and I presume each one is dimmer than it's single color emitter counterpart, but if I were picky, I'd say I preferred having three tri-colored emitters over three brighter single-colored emitters for the sake of the beam. However, I won't be that picky 

The beam pattern on the TK32 definitely shows the effects of having emitters on the side. Up close, the white beam shows visible beam artifacts, though they do fade out of noticeability as the distance increases. The colored beams are of course very weird shaped, as you can see in the pictures above. I suppose Fenix could have set these down a bit closer to the center of the reflector to make the color beams a bit more round, but this undoubtably would have been at the cost of the shape and even the throw of the main white beam, so overall I think it's a good compromise. If you're looking for a perfect beam that's maximally reflected and you don't care about having colored beams, the TK32 isn't right for you, but if you want the color beams, then be assured that the TK32 does them very well and their affect on the main beam is minimal. 

The regulation of the TK32 is very good - in fact, it's pretty much exactly what I like to see. The Turbo mode throws out the max brightness your battery can handle for about 15 minutes, then drops approximately the level of the High mode, and in my mind that's just what "Turbo" should mean--pushing as hard as it can for a short time only. You can turn it off and back on to get back to Turbo if you desire, but it's wise to let some heat dissipate first. The High mode is very flatly regulated for the majority of it's run time, then when the batteries get low it drops to a still usable level that is also regulated. This is a sort of warning, because after that will come another drop to a very low output, which is just about enough light to find your backup batteries in the dark (which I find is infinitely better than lights that are fully regulated until the battery dies, then just shut off and leave you in the dark). The Low mode I measured to be about 7 lumens, pretty close to the 10 they claim, which I appreciate as a good light level for close-up work. I generally like a bit of a lower minimum output, but the TK32 is pretty much a throw-oriented light, and a beam that tightly focused isn't extremely useful up close at any light output, so I'll be carrying something dimmer and floodier for prolonged close use anyway. 

I appreciate the user interface on the TK32, using separate buttons for power and mode control, but keeping the buttons close together so that you don't have to switch you grip to use either one. I especially like the momentary red function available by holding the mode button when the light is off--this pretty much makes up for the lack of a white super-low mode, because I can use it to preserve my night vision or avoid attracting attention. Additionally, as I mentioned in the UI section above, I found by accident that you can make the momentary red mode become constant red by pressing the power button while already using the momentary red. I don't remember this being in the manual (I'll be checking later) so I don't know if it's intentional, but I really appreciate it.

There were just a few negatives I found with the TK32. I already mentioned the rings in the beam when up close or using the color modes, and the fact that I know tri-color emitters exist . In addition, I saw that Fenix claims the TK32 has "anti-roll" design, which is just plain silly, because it definitely rolls when placed on a flat surface. Last, the knurling is just a bit rougher that I generally like, but I'm sure there are situations where I will appreciate it. I just generally prefer grip to come from the shape of the light instead of the knurling.

Overall, the TK32 is an excellent light by Fenix, and I've really enjoyed using it. As I said, very few high-end lights implement colored emitters, and the TK32 does this very well with minimal sacrifice of the main beam. It's still on the high end of brightness for single-cell lights, and has good throw for it's class as well. If you're looking for a general thrower with the addition of a multiple beam colors, the TK32 should definitely be on your list to consider!

Long Term Impressions
I'll fill this part in after carrying the light for a while. If nothing get's added here, either I find nothing else worth noting about the light, or I end up not using it often.

7.28.14 A feature has been pointed out to me that I neglected in the original review. In order to have both the mode and power switches in the tail, Fenix has designed the TK32 with a "dual layer battery tube" so that power can flow through the power switch independently of the signals that must flow through the mode switch. I've included a picture below that shows the two separate conductive layers in the body of the light, one inner and one outer.

Original text link:

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