Reviewer's Note: The LF3XT was purchased from CPF dealer LED Cool - see his Dealer's thread in CPFM.
UPDATE AUGUST 10, 2009: My review of the replacement tailcap with clip and 2xAA battery tube is now up.
UPDATE: After completing the review, my purchased LF3XT developed a fault on primary CR123A. LED Cool not only sent me a replacement unit, but one extra light to review as well. Summary results for all 3 units have been added to the review. To see detailed runtime comparisons, scroll down to post #2.
Warning: Pic heavy!
Manufacturer's claimed specifications
- LED : CREE XR-E Q5 bin
- Approximate LED current at 100% output level : 700ma when using CR123
- Input voltage : 2.0V - 4.5V (CR123/16340)
- Battery chemistry allowed : Primary Lithium CR123(3.0V), rechargeable Li-Ion 16340(4.2V) & rechargeable LiFePO4.
- PWM Frequency 7800Hz.
- Material = 6061 T6 Aluminium Alloy.
- Tail press button machined from 6061 T6 Aluminium Alloy with shinny finish.
- AR Coated glass lens.
- Finishing : available in 1 colour - BLACK HA III.
- O ring seal at lens, battery tube and tack switch.
- Split ring hole at tail end. Stable tail stand.
- All parts can be disassembled for cleaning and maintenance.
- Water resistant for daily normal use. NOT suitable for diving or swimming.
- Size: 80mm length. 23mm diameter.
- Standard Accessories: Lanyard, 2pcs spare O rings, A small container of silicon lubricant for the o-rings, Instruction manual
The LF3XT is the latest offering from LiteFlux, building on the circuit and design of their sophisticated 1AA model, the LF5XT. This version actually features two separate user interfaces that you can switch between - a compact one that is very similar to the Nitecore EX10, and complex one that is closer to the Novatac 120P (but with more features and control).
The LiteFlux packaging is similar to older LF series, and comes with a nice wooden presentation box. Package contains a manual, wrist strap, spare o-rings, and lube. The wrist strap seems to be of fairly high quality, and is a nice addition.
(sorry for the dusty pics coming up, I was in a hurry )
The two-stage body design is fairly compact for a 1xCR123A/RCR light, and features a deep reflector and programmable clicky (scroll down for detailed pics).
Length x Width: 80.7mm x 23.0mm
Fit and finish is excellent on my sample - lettering is very clear and sharp, and the black type-III hard anodizing is flawless. Labels are kept to a minimum (although I’ve personally not crazy about Liteflux’s stylized italics font).
The knurling is improved over early LiteFlux lights, where it was more for decoration - although still not overly aggressive here, it does help with grip. I do find the four protruding corners of the base a little sharp, and could stand to be rounded further.
The light uses the common Cree Q5 emitter, since R2s remain frustratingly hard to get in volume. All lights use premium cool white emitters, but LiteFlux dealer LED Cool may be able to select relatively warm/cool tints for those who are interested.
Reflector is deeper than most 1xCR123A/RCR lights, and is very finely textured - to the point where it appears like a fine haze over the reflector surface. Fairly unique to LiteFlux, this appearance actually reminds me a bit of my DIY sputtering jobs (although far more consistently applied here, of course). Scroll down for beamshots.
Build of this light is different from most. Since it uses a MCU in the head, a separate current path needs to be provided for the modes to work reliably. Like the LF5XT, there is a brass sleeve that the battery sits inside, which connects the tailcap switch to the retaining ring in the head. A good comparable would be the Novatac lights, where this is done with a spring that runs around the battery.
Although it may look similar to the NiteCore "Piston Drive", the LF3XT still uses an actual tailcap switch underneath the battery sleeve. But the switch is not your typical clicky - it is more like those found on modern electronic devices. A good way to describe it is like the on/off button on your LCD monitor, as compared to the traditional clicky switches found on old CRTs. The feel is actually more similar to the Novatac series lights, but with less tactile feedback on my LF3XT sample.
The screw threads are anodized on the body tube, so lock-out is possible.
Note that unlike the LF5XT, the battery sleeve doesn't appear to be user-removable - it doesn't seem to want to come out on mine at any rate, and I don't plan to force it.
UPDATE JANUARY 13, 2009: Seems like the battery sleeve can come out - you need to unscrew the tail retaining plate (using a small screwdriver in the lanyard hole, and turning counter-clockwise from the body tube). The battery sleeve then falls out of the back-end of the body tube.
The switch can also be disassembled from the tail retaining plate, using a pair of fine tweezers or snap-ring pliers. Here's what you'll find inside:
The LF3XT is a remarkably versatile light, with a dual user-selectable interface that should please KISS-fans as well those wanting a fully user-customizable light.
But first a warning: there is a lag before a button press is registered by the MCU and the light responds. This means a noticeable lag in operation - but it also means you can't rapidly double-click within 0.3 secs, or the light won't register the two separate actions (i.e. you have to allow 0.3 secs between each click). This takes some getting used to - but once you master taking it a bit slower, you should have no problems controlling the light.
In Compact User Interface (CUI), the light is remarkably similar to the Nitecore EX10 - but with a few improvements. The EX10 interface is pretty simple - with the head fully tightened, click for on/off. When on, press and hold to begin the ramp, release to select the desired level. Shortcuts to min (double-click) and max (click-press/hold) are included.
The main complaint with the EX10 interface is that your custom-set level is erased when you use the shortcuts (i.e. jump to min, and min is now your new custom-set level). The second complaint is that you have try twice to activate the ramp after using a shortcut, since it remembers the previous ramp direction.
In contrast, the LF3XT retains the user-selected output even when shortcuts are used. The way this works is that the shortcuts are actually a toggle - e.g. double-click for min, double-click again and you are back to your pre-selected user level. This is actually very useful, except it also means that every time you turn the light on it comes back to the user defined level (i.e. if you use the shortcut to min or max and turn off the light, it will still come back on at the pre-defined level). This is likely an improvement for more users, although probably not ideal for all.
The LF3XT ramp works as expected on every attempt. You can also re-program your LF3XT to act as a momentary-on instead of click-on (like you can do on the EX10 by unscrewing the head slightly), but I find this less useful for either interface.
The Full-Function User Interface (FUI) is much more complex, and similar to the LF5XT. Although the light is easy to use in practice once programmed, I suspect you will find you need to refer to the manual frequently when you want to re-program any features. Please refer to LED Cool's dealer thread on CPFMP or the discussion thread here on CPF for more info on how to use it. There's also a revised english manual maintained by matrishaman here, and a programming flowchart that Budman231 created (for those more visually-inclined).
One revised feature that I will mention is the low voltage over-discharge protection system has been separated for NiMH and Li-ion cells. Although the LF3XT only takes 1xCR123A/RCR at present, an optional 2xAA battery tube is planned for the near future.
I plan to do a review of the 2xAA battery configuration once it becomes available. We will see if they have fixed the issue with the low-voltage shut-off problem with the LF5XT. Briefly, that light always shut-off on NiMH or alkaline at ~1V, regardless of whether the low voltage over-discharge protection feature was enabled (see my LF5XT review for more info).
Personally, I find the CUI very well suited to EDC use. Fans of the Novatac-style lights or LF5XT may prefer to use the sophisticated FUI (which you can customize to exactly the way you want). But the CUI is pretty intuitive and easy to remember right out of the box.
From left to right: Duracell CR123A, LiteFlux LF3XT, Nitecore EX10, Fenix P2D, Dereelight C2H, JetBeam Jet-II PRO, Novatac 120P, Nitecore Extreme
As you can see, the light is a bit bigger than the Nitecore EX10, but I actually like the extra heft.
All lights are on 100% on AW RCR, except for the Surefire E1B which is on primary Duracell CR123A. Distance is about 0.5 meters from a white wall.
As you can see, the beam profile is very distinctive on the LF3XT - you have a much narrower (but brighter) spillbeam than most lights, thanks to the deeper reflector. Cree rings are also greatly reduced, and the hotspot is a little broader than most lights. Frankly, I find this profile to be a lot more SSC-like than Cree-like. Tint on my sample is quite warm, which I personally like (I asked LED Cool to select a warm tint).
Testing Method: All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for the extended run Lo/Min modes which are done without cooling.
Throw values are the square-root of lux measurements taken at 1 meter from the lens, using a light meter.
Throw/Output Summary Chart:
LF3XT’s peak throw is toward the lower end of my 1xCR123A/RCR lights, but that's not necessarily a bad thing for an EDC (it is pretty comparable to the Novatac or Incendio).
Max overall output is fairly typical for a light this size, and consistent with the reported 700mA driving current (there are larger lights that are more heavily driven). Low output is particularly impressive - on primary CR123A, the LF3XT can actually go as low as my Novatac 120P. This is even lower than the LF5XT.
UPDATE: With the receipt of the extra 2 samples, I've added their output/throw results to the table above. As you can see, there is no real difference in terms of overall output. However, throw varied a bit - one new sample had ~10% more throw than the original, and the other had ~20% more throw. I suspect this is due to slight differences in how well-focussed the samples were set in the factory.
Variable Output Ramping
The LF3XT has two ways to adjust brightness through the FUI - step-wise "logarithmically" (which is visually-linear) or "linearly" (which will take you in much slower steps). The CUI uses a visually-linear ramp upon press-and-hold that is much faster than the FUI manual stepping. It is in fact very similar to the Nitecore EX10 and ITP C9 (shown above). The LF3XT fast CUI ramping time is about ~1 sec longer than those lights.
Max output and runtime pattern are remarkably similar between the LF3XT and the Nitecore EX10 - although my EX10 sample has longer runtime on max. I suspect this is largely due to variation in Vf, so YMMV.
On the lower outputs, the LF3XT tends to have a slight runtime advantage on RCR, but is less tightly regulated than some of the other lights shown here. I haven't done as many lower mode CR123A runs, but performance is definitely in keeping with the competition so far.
In summary, no major surprises here - the LF3XT performs pretty much as I would expect for a continuously-variable light.
UPDATE: To see the runtimes of the two new samples, see post #2. Frankly, I've very impressed at how little variability there was in output or runtime.
As mentioned previously, the 0.3 sec lag in responding to some button presses takes a little getting used to. The button also has a much shorter traverse, in keeping with an electronic switch as opposed to a traditional clicky. Not really problems per se, just a different set of expectations.
That being said, I have found the button feel of my LF3XT to be a bit soft, leading to uncertainty if a press has been registered (i.e. sometimes lacks tactile feedback). Can't say I had any problems with my LF5XT, which was crisp and clear for this type of switch.
UPDATE: Scroll down this thread for a further discussion of this issue, and a potential resolution. Of the replacement samples, I found one has a very crisp feel, while the other feels much like the first sample described here. This can be improved with a little user maintenance.
I'm very impressed with my LF3XT.
The most remarkable thing about this light is the dual interface. They've taken the powerful-yet-simple UI of the Nitecore EX10, and the advanced programmable UI of the LF5XT/Novatac, updated both with new features, and then put them together into one light!
Having EDCed lights using both approaches over the years, I appreciate the merits of each method. But to able to have both in one light, with the ability to easily switch between them, is brilliant. Credit where credit is due - my hat's off to LiteFlux on this one.
It's nice to see the small touches on this circuit that improve over other lights. The enhanced memory mode for the user-selected level in the CUI is a nice addition over the EX10. LiteFlux has also taken the minor issues associated with the LF5XT - which was a good light, but had a few quirks - and corrected them with the release of the LF3XT. Note that min output is now close to my Novatac 120P, something the LF5XT couldn't match.
The LF3XT beam is also very nice, with one of the smoothest transitions from spot to spill I've seen in a Cree light (very SSC-like, in fact). Keep in mind the LF3XT is not a thrower, and the spillbeam (although bright) is narrower than most lights. This is not really a problem - I discovered while carrying my LF5XT around that you quickly adapt to it (i.e. I had unconsciously switched from carrying the light forward in front of me, to holding it up closer to my head, before figuring out why the beam didn’t seem so narrow after all! ).
Another reason I bought this light is for the planned 2AA battery tube option, expected to be available soon. Although I know many manufacturers who promised updates that never came, I am impressed that they've already programmed into the circuit separate control over low-voltage/battery shut-down options for unprotected Li-ion and NiMH. The LF5XT is the first light I've seen with this clever feature for NiMH, and I'm looking forward to seeing how it works on the LF3XT once the 2AA tube comes out.
Build quality feels really solid and well made. In fact, my only niggling issue is with the button feel, but that could be specific for my light (again, I thought the LF5XT switch was fine, once you got used to it). That, and a clip would be nice.
What more can I say – there’s a lot to love here. Well done!
P.S.: My review of the replacement tailcap with clip and 2xAA battery tube is now up.