The IF25A is a popular compact every-day-carry light, running on an included single 21700 battery. It also features the sophisticated Anduril user interface.

1. Introduction
2. Manufacturer Specifications
3. Package Details
4. Build
5. User Interface
6. Circuit Measures
7. Emitter Measures
8. Beamshots
9. Testing Results
10. Runtimes
11. Pros and Cons
12. Overall Rating
13. Preliminary Conclusions
14. Acknowledgement

Introduction

In my absence from reviewing, another popular premium “budget” maker that has come on the scene is Sofirn. Making a series of affordable but powerful lights, I was curious to give them a try. So I purchased their popular compact 1×21700 model, the IF25A.

Note that this light has been around for a while now, so its performance may not be quite as high as some of their newer offerings. And my sample was purchased last fall – it took me awhile to get around to it, given all my requested reviews.

The IF25A is quite a tiny little tank of a light, and features 4x Luminus SST20 emitters. The light comes with a choice of either warm (4000K) or a cool (6500K) white LEDs. This review is of the cool white IF25A, in order to compare with other lights configured for maximum output.

Note this will be the second light I’ve tested that uses the open-source Anduril user interface (although I know it uses an early implementation of Anduril 2). Let’s see how the light performs in my testing.

Manufacturer Specifications

Note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results.

Feature	Specs
Maker	Sofirn
Model	IF25A
Emitter	4xSST20
Tint	6500K
Max Output (Lumens)	4,000
Min Output (Lumens)	-
Max Runtime	-
Max Beam Intensity (cd)	-
Max Beam Distance (m)	420 m
Mode Levels	5 + Ramp
Flashing	Strobe
Battery	1x21700
Weight (w/o battery)	99 g
Weight (with battery)	-
Length	106.4 mm
Head Diameter	35 mm
Body Diameter	35 mm
Waterproof	IPX-8

Package Details

The IF25A comes in typical cardboard box, with fairly simply background illustrations and basic light details (I know some of the newer Sofirn models come in fancier packaging). Inside, I found:

• Sofirn IF25A flashlight
• Sofirn-branded 4000mAh 21700 battery (note some distributors may include a higher-rated cell)
• A 18650 battery sleeve
• Wrist lanyard
• USB-C Charging cable
• 2 Spare O-rings
• Manual

It’s a decent package for a budget build. I would have liked a pocket clip and a higher capacity cell though, to match the competition (again, newer versions may come with a higher capacity cell). I do appreciate the USB-C charging cable – I have plenty of these lying around, but it always nice to see one included in a budget package.

Build

From left to right: LiitoKala 21700 (5000mAh), Fenix ARB-L21-5000U 21700 (5000mAh), Sofirm IF25A, Fenix E35 v3, Convoy S21E, Imalent MS03, Armytek Wizard C2 Pro Max, Acebeam E70, Nitecore P20iX, Nitecore MH12SE, Lumintop D3, Convoy M21F.

The IF25A is shorter than most lights in this class, despite the multi-emitter head. Despite that, it actually feels very robust, with a nice thick body. A surprisingly tiny but substantial build at the same time.

There is a side-mounted electronic switch on the side of the light near the head, with a grippy rubber cover that still allows the red and green LEDs underneath to shine through. Feel and traverse of the electronic switch is good. Note that by default the switch shines a constant low output dual-green when the battery is connected but not in use or charging (brighter green in those conditions). I initially found this constant “locator” feature is a bit annoying – but you can turn it off, or switch it to a brighter green (which actually has an important potential use – scroll down to User Interface for a discussion).

The button also shines a bright red when charging the battery through the light’s integrated USB-C charging port. The port is located on the opposite side from the switch, with a thick rubber cover. I found the cover to fit rather tightly, making it hard to full depress. But I suppose that should help with waterproofness if you can press it down enough.

I always recommend you keep a light stored locked out when not in use. Thanks to the anodized tailcap threads, you can do this easily on the IF25A by a simple twist of the tailcap. Threads are square-cut, and well lubricated. The light can tailstand stably, thanks to the side cut-outs for the wrist lanyard.

There is no actual knurling on the light, just a series of cut-outs at various points. Combined with somewhat glossy anodizing, this makes the light fairly slippery in use – I would have preferred some knurling elements. Note the light can also roll fairly easily, although the slightly flared tailcap helps a little bit with this (as does the rubber port cover). The anodizing seems in good shape on my sample, but I suspect it is only the thinner type II, given the price point.

Note that no pocket clip is included, and it would be a challenge to carry the light that way given the wider head and flared tailcap. Personally, I would have preferred a narrower tailcap and a clip option, since I don’t think thin wrist lanyards are of much use. Not a bad physical build by any means, but it does feel and look somewhat budget. I also find it a bit too short, but I have larger than average hands.

My sample came with a Sofirn-branded standard-sized 4000mAh 21700 battery (higher capacity may be sold by some vendors), with a slightly raised flat-top (also called a wide button by some).

A battery sleeve is also included, in case you want to use older 18650 cells (again, a nice touch in a budget light). I suspect a button-top would also work fine in the light, but it would need to be compact given the small size here (and certainly, none of those 21700 cells with built-in charging ports would fit). Note there is no spring in the head, just a flat contact disc (which helps explain the more compact length).

The IF25A uses 4 non-frosted TIR optics instead of individual reflectors, allowing the head be quite a bit shorter than most. I actually recommend the use of TIR optics for multi-emitters, as it tends to minimize beam artifacts. It also shines a generally “smoother” beam, with less differentiation between hotpot and spill. The beam looks reasonably clean on my sample, with just a few artifacts.

Note that I did observe some tint shifting on the lower levels (i.e., the lowest output has a definite greenish hue). This is not uncommon on current-controlled lights (e.g., Fenix), but is particularly noticeable here.

The bezel is flat black aluminum, with no crenelations – so, it can headstand stably, but you may not be able to tell if the light is on. I don’t see any form of AR coating on the lens.

There is a very interesting option with this light, using the switch indicator (green LEDs) when the battery and tailcap are connected. As I will explain below, you can increase the output of the default setting, giving yourself in essence an extra “moonlight” mode. Here is what it looks like, close-up on a white wall in the dark (not really this bright, using my cellphone’s auto-adjust mode):

The green is very even and surprisingly bright with dark-adapted eyes. Scroll down for more details on how to configure.

User Interface

The IF25A uses the open-source Anduril user interface (UI). Although the site I bought it from describes (and displays) the original interface of the inaugural Anduril release, I can confirm that my sample actually uses Anduril 2 (just like the Lumintop D3 I previously reviewed). I understand from ToyKeeper that it is actually an early implementation of it.

Anduril has two distinct UIs mode sets: Simple and Advanced. The labels are a bit misleading, as both are fairly sophisticated – it is just that the Advanced UI has a lot of extra options not available on the scaled-down Simple UI. Advanced UI also has an option for a discrete Stepped level mode, in addition to the continuously-variable smooth Ramping mode (which is the only mode present on the Simple UI).

To switch from the default Simple UI to Advanced UI, you need to do 10 clicks from Off, with a hold on the 10th click.

It’s easier to show the UIs rather than explain them in words, so here is a common pic:

You can also download a fully described text manual here.

Like the Lumintop D3, my IF25A only has 5 discrete Stepped modes in the Simple UI (all 7 show up under Advanced UI though). Since most people are likely to leave it in the Simple UI, I’ve gone with 5 discrete levels my tables, and labelled L1-L5 as Moonlight, Lo, Med, Hi and Max/Turbo.

Again, check the image and link above for more info, but here is a simplified description of the UI to get you started.

From OFF:

• • Press-and-hold: Turns On in lowest output, in either Ramping mode or Stepped mode depending on which mode is enabled (and which UI you are in)
  • Single-click: Turns on in last memorized mode used (Ramping or Stepped)
  • Double-click: Turns on to Turbo (aka the Ramping max output)
  • Triple-click: Battery check (voltage read out a single time)
  • Triple-click-and-hold: Special strobe modes, but only when in Advanced UI (remembers last strobe mode used)
  • 4 clicks: Lockout mode. In lockout mode you have different options available:
    • Press-and-hold: Momentary Moonlight
    • Double-click-and-hold: Momentary Low
    • 4 clicks: Turns On in memorized output level
    • 4 clicks and hold: Turns On in the lowest level
    • 5 clicks: Turns On in Turbo
    • 10 clicks and hold: Configure the lock timeout threshold (in Advanced UI only), allowing you to pre-set the timeout time of the lock.
  • 7 clicks: (Advanced UI only) Enters auto light config for the button switch (“AUX/Button LEDs”). There are four modes you can switch between; constant low, blinking low, off, constant hi. Click 7 times again to advance to the next option, in sequence. The light auto-memorizes the last option you select. This allows you to use the switch LEDs as an impromptu “green moonlight” mode, as explained below.

From ON:

• Press-and-hold: Ramps up (or Steps up, depending on the mode). Ramps/steps down if you do it again.
• Single-click: Turns Off
• Double-click: Jumps to Turbo
• Double-click-and-hold: Ramps down (or Steps down)
• Triple-click: Switch between Ramping and Stepped modes (in Advanced UI only)
• 4 clicks: Lockout mode (see above for options)

Mode memory:

Yes, the circuit memorizes the last constant On output level in either Ramping or Stepped modes.

Strobe/Blinking modes:

Yes, quite a few actually. The strobe/blinking modes are accessible from Off with a triple-click-and-hold, but in Advanced UI only. You can switch between strobe/blinking modes with 2 clicks, in the following sequence (see testing results below to see what these look like):

• Candle mode
• Bike flasher
• Party strobe
• Tactical strobe
• Lightning

Low voltage warning:

Sort of. In operation, the light drops in brightness in steps, and runs for an extended time at a very low level. Apparently it shuts off when the cell is ~2.8V (although I haven’t run it that long to confirm). I haven’t noticed any change in the switch LEDs to indicate low battery voltage (which seems like a missed opportunity, given they have red and green LEDs under there).

Lock-out mode:

Yes. In either Simple UI or Advanced UI, lockout is accessed by 4 clicks from On or Off (repeat to unlock). The lockout mode is unusual with Anduril, as it actually enables momentary operation in the Moonlight/Lo modes. There are other lockout modes available, as explained above. As always though, I recommend you physically lock out at the light at the tailcap, if you want to guarantee no accidental activation.

Temperature check and thermal calibration mode:

This is a little complicated (and beyond the needs of most users), so I will just refer you to the diagram from the manual above. With default settings, I find it steps down fairly quickly due to heat (unsurprising, give low thermal mass in the head). I have not tried to reconfigure my sample.

Reviewer Comments:

Anduril is a fairly sophisticated setup – a choice of Simple or Advanced UI, generally well thought out. Of course, you will never please everyone, and many may prefer a slightly simpler interface (e.g., the Convoy S21E), or even very basic one (e.g., Acebeam E70). While I can see flashaholics enjoying some of the extra items, some of them are really novelties (e.g. candle mode and lightning storm are particularly well done, but when would you practically ever use them other than as a party trick?). At the end of the day, I expect Simple UI is fine for most users. That said, the Stepped mode and bike strobe are something that many could use, so it’s nice to have them as options in the Advanced UI.

One of the main advantages of Anduril in a build like this is the ability to independently control the green LED emitters under the switch cover. By keeping the constant-on default setting (or increasing to brighter green), you can basically turn this into an additional “green moonlight” mode on the light. Simply use the light as a twisty: tighten the tailcap for moonlight and access to all the main modes, loosen the tailcap for a physical lock out. 🙂

Circuit Measures

Pulse-Width Modulation (PWM):

There is no sign of PWM on any level, the circuit appears to be fully current-controlled.

That being said, my oscilloscope was able to detect high frequency noise at all levels except max output, as depicted below. Note that these are not actually a concern, as they are not visible to naked the eye – the light remains flicker free in actual use. But I’ve noticed upon my return to reviewing that a lot of “budget” circuits are showing detectable signs of circuit noise. Using the Simple UI’s 5 discrete Stepped levels:

Level 1 (Moonlight):

Level 3 (Med):

Level 4 (Hi):

Level 5 (Max):

As you can see, noise begins with L1, at ~9.2 kHz. For L2 through L4, noise frequency remains constant at ~15.4 kHz, but increases in amplitude as output levels rise (which is fairly common, as more light is being emitted) – except for L5, which is noise free, oddly. Noise at these super high frequencies is impossible to detect visually, and so again not a concern. I am just including for completeness, as I like to present all my findings.

Strobes:

Tactical Strobe:

Tactical strobe is a fairly typical 10.1 Hz, although the light spends more time in the On phase than the Off phase on each cycle.

Party Strobe:

Party strobe is a super-fast (and annoying) short pulse at 25 Hz. I don’t know what kind of rave parties the Anduril folks like to hold, but I won’t be attending any. 😉

Lightning Strobe:

I’ve shown five consecutive 10-sec cycles above, so you can a feel for the frequency and intensity of light flashes. Lightning strobe is a fairly realistic lightning simulation, with variable intensity and time between flashes.

Bike Strobe:

Bike strobe is a nice, slow 1 Hz signalling strobe – but with with 4 rapid flashes on every signal (shown in more detail below).

Beacon:

Beacon strobe is a slow 0.5 Hz.

Candle:

Candle strobe is a continuous flicker, of varying intensity (again, accurately simulating a candle).

Charging:

The switch button shines a bright red when the light is charging (switches to bright green when the charging is complete).

Resting voltage <3.0V

Resting voltage >3.0V

The IF25A has a two-stage charging feature (i.e., with a lower charging rate for when cells are heavily discharged). With a heavily depleted cell (<3.0V), the initial charging voltage is a relatively low 0.32A. Once the resting voltage of the cell >3.0V, the charging current jumps to ~1.6V. Over the next few mins, it will continue to slowly rise a bit higher.

Note that the light drops to a very low level when the battery is nearly depleted, but there is no specific low voltage warning that I’ve noticed (e.g., there is no warning flash, and the button LED remains green throughout when the light is on unless you disable that feature). It will apparently shut-off at ~2.8V, but I never ran it that far to find out.

Standby / Parasitic Drain:

I measured the standby current (with default low green switch LEDs active) as 78 uA, which is negligible and not a concern (i.e., it would take many years to fully drain the cell). Regardless, I always recommend you lock the light out when not in use to prevent accidental activation (and cut any standby drain). A single twist of the tailcap will lock out this light, thanks to the anodized screw threads. And special bonus, this means you can use the tailcap twisty as a de facto “green moonlight” mode with the switch LEDs.

Emitter Measures

This section is a new feature of my reviews, where I directly measure key emitter characteristics in terms of colour temperature, tint, and colour rendition. Please see my Emitter Measures page to learn more about what these terms mean, and how I am measuring them.

As explained on that page, since I am using an inexpensive uncalibrated device, you can only make relative comparisons across my reviews (i.e., don’t take these numbers as absolutely accurate values, but as relatively consistent across lights in my testing).

As with all my reviews, the reported CCT and Duv measures above are for the first stable output mode without stepdown – which, in this case, is L3 (Med) on the Stepped Simple UI. The key measures above are the colour temperature of ~5265K, and the very noticeably positive tint shift (+0.0174 Duv) to green-yellow at this temperature.

For CRI (Ra), I measured a combined score of 59 on this level.

These values are very consistent with Luminus SST emitters, and match my visual experience of this light.

Given the subjectively stronger green tint-shift I noticed on the lower outputs, I decided to actually measure the Duv tint shift of each discrete Stepped level on the Advanced UI, as shown below.

L7: ~5225K, Duv +0.0169
L6: ~5240K, Duv +0.0178
L5: ~5165K, Duv +0.0192
L4: ~5000K, Duv +0.0223
L3: ~5000K, Duv +0.0222
L2: ~5030K, Duv +0.0218
L1: ~5095K, Duv +0.0211

As you can see, the CCT doesn’t change much (i.e., typically stays within ~5000-5250K), but the positive (green) tint shift is greater at the lower levels (L1-L4) compared to the higher levels (L5-L7).

Beamshots

All outdoor beamshots are taken on my Canon PowerShot S5 IS at f/2.7, 0.5 secs exposure, ISO 400, daylight white balance. The bend in the road is approximately 40 meters (~45 yards) from the camera. Learn more about my outdoor beamshots here (scroll down for the floody light position used in this review).

Click on any thumbnail image below to open a full size image in a new window. You can then easily compare beams by switching between tabs.

I did a second set of beamshots at this location more recently, showing two more relevant lights:

As you can see above, the beam pattern for IF25A is more on the floody side, as expected give the multi-emitters and shallow TIR optics.

Testing Results

My summary tables are generally reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. In addition to the links above, please see my output measures page for more background.

All my output numbers are based on my home-made lightbox setup. As explained on that methodology page, I have devised a method for converting my lightbox relative output values to estimated lumens. My Peak Intensity/Beam Distance are directly measured with a NIST-certified Extech EA31 lightmeter.

IF25A Testing Results

Mode	Spec Lumens	Estimated Lumens @0sec	Estimated Lumens @30 secs	Beam Intensity @0sec	Beam Intensity @30secs	Beam Distance @30secs	PWM/Strobe Freq	Noise Freq	Charging Current <3V	Charging Current >3V	Parasitic Drain	Weight w/o Battery	Weight with Battery	CCT (K)	Duv	CRI
L1 Moonlight	-	1.4	1.4	-	-	-	No	9.2 KHz	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
L2 Lo	-	74	74	-	-	-	No	15.4 kHz	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
L3 Med	-	450	440	-	-	-	No	15.4 kHz	0.32 A	1.6 A	78 uA	98 g	163 g	5,265	0.0174	-
L4 Hi	-	1,650	1,550	-	-	-	No	15.4 kHz	0.32 A	1.6 A	78 uA	98 g	163 g	5,280	0.0169	59
L5 Max	4,000	3,400	3,050	30,500 cd	24,800 cd	315 m	No	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Candle	-	-	-	-	-	-	-	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Bike Strobe	-	-	-	-	-	-	1.0 Hz	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Party Strobe	-	-	-	-	-	-	24 Hz	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Tactical Strobe	-	-	-	-	-	-	10.1 Hz	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Lightning	-	-	-	-	-	-	-	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-
Beacon	-	-	-	-	-	-	0.50 Hz	No	0.32 A	1.6 A	78 uA	98 g	163 g	-	-	-

My measured max output is considerably below the rated spec, as are my beam distance measures. The rated specs definitely seem inflated on this sample. That said, I do like the inclusion of the relatively low min output mode here (i.e., ~1.4 lumens). Not quite as low as I would like for Moonlight, but I’ll take what I can get given how rare actual Moonlight modes seem to be nowadays.

To see full testing results for all modern lights in my testing, check out my Database page.

Runtimes

As always, my runtimes are done under a small cooling fan, for safety and consistency. To learn more about how to interpret runtime graphs, see my runtimes methodology page.

For thermal reasons, both the (L5) Max and (L4) Hi runtimes quickly stepped down from their initial values to ~750 lumens or so, and stayed within a ~100 lumen range of that point for most of their extended runs (scroll down to see this with better resolution). You may be able to adjust this somewhat through the Anduril settings, but ultimately I suspect the low thermal mass of the light is the culprit here.

At the (L3) Med level, you get a semi-regulated runtime pattern (i.e., much closer to direct-drive over most of its run).

Something else you’ll notice in the full runtimes above is that the IF25A regulation pattern is quite “noisy”, demonstrating significant fluctuations in output over time (even at the “regulated” lower level). In practice, these fluctuations are not noticeable (i.e., they are actually fairly minor and slow over human perceptual timescales, and thus unnoticeable).

Here is a blow-up of the (L5) Max output runs, for both Ramping and Discrete Stepped, on a shorter time scale, to show you both the step-down and relative stability:

As you can see, there is no real difference between the discrete Stepped mode set and the Ramping (unlike some earlier reviews out there). It seems like Sofirn fixed that earlier issue.

To better show the effect of the “noisy” pattern above, here is a blow-up in even more detail, over a 2-min portion of the run when the changes in output were the most extreme (on the discrete Max output run):

Again, these are not a concern as you will not be able to notice these kinds of subtle outputs changes in real life. Nevertheless, I would prefer to see more stable and consistent regulation across all modes, as the pattern above is a sign of a very basic budget circuit.

Which brings me around to the key point – overall efficiency of the IF25A appears lower than others in this class. Keep in mind my sample IF25A came with a 4000mAh battery, which is 20% lower capacity than most of the competition above. Still, the runtimes are  disappointing compared to lights with fully-regulated current-controlled circuits (e.g., the more expensive Nitecore P20iX, but even the budget Convoy M21F).

Part of this could be due to the relative efficiency of the multiple SST20 emitters (especially in a small head where heat management is an issue). But I doubt that is the main issue, as they are not being driven very hard at these lower “regulated” levels. It seems far more likely that the issue is with the driver. Which is a real shame, since Sofirn opted for the sophisticated Anduril UI – it would have been nice to have seen it paired with an efficient current-controlled circuit here.

I realize this IF25A model is getting a little long in the tooth now, but I still recommend Sofirn look into the improving both the regulation and the efficiency of the circuit on this model while it is still available.

Pros and Cons

Pros	Cons
Comes with the sophisticated Anduril UI, which has both simple and advanced options.	Light steps down quickly on Max/Hi levels to a relatively low ~750 lumens for the remainder of the runtime (for thermal reasons)
Small and sturdy physical build.	Driver output efficiency is below average for the class, consistent with entry-level budget lights.
Relatively floody beam, without too many artifacts from the multiple emitters.	Regulation pattern is not impressive, both in terms of its relative spiky "noise" pattern, and semi-regulated appearance.
Thanks to the configurable UI, you can use the green LED switch indicator as an effective Moonlight mode.	Rated specs for max output and beam distance are over-inflated in my testing.

Overall Rating

Preliminary Conclusions

The Sofirn IF25A is a serviceable build, with a decent (and sophisticated) user interface with a floody beam profile. It is a particularly compact yet sturdy light, which should appeal to many. That said, I would like to have seen a bit more refinement in the physical build (e.g., actual knurling, less-flared tailcap with pocket clip, etc.).

I realize this is an older model that has been around for a while, so it may not be entirely fair to compare it the newer competition. But the overall impression I have is one where they consistently skimped a bit on many aspects of the light. While each one may not seem like a big deal, the overall effect adds up over time. The most significant one is the circuit – both regulation and efficiency were sub-par, consistent with the most basic budget builds (yet many do better, as shown above). I find increasingly that this is something that differentiates the most entry-level budget lights from the intermediate or premium ones. At the end of the day, I find circuit performance really matters to me.

This is also an example where the rated max output and beam distance specs are clearly inflated. Since my return to reviewing, I’ve generally been pleasantly surprised to see much better concordance of my testing results to the rated specs (compared to the Wild West of my early days of reviewing). So when I see a clear mismatch now, as in the case of this light, it leaves a poor impression.

All scoring is relative, and bound to be a bit idiosyncratic, but I initially gave this light 3 stars overall. I’ve since upgraded that to 3.5 stars, as I find the green switch LEDs (especially set to high) to act as a very serviceable “green moonlight” mode. This is one of the plusses of having the sophisticated Anduril 2 UI, combined with a reasonable initial minimum and max output levels on the main emitter. But again, Max/Hi levels step down quickly to ~750 lumens for thermal reasons – which is a bit lower than the competition. And the main beam tint on all levels below Max/Hi is decidedly green on my sample.

The build quality seems relatively decent for a budget brand, and with a few noticeable refinements, this light could easily move into a higher tier. The quality and features inspire enough hope that I am looking forward to reviewing additional Sofirn lights.

Acknowledgement

The IF25A was purchased through an online vendor from China (aliexpress). As always, all opinions are my own and the light received the same rigourous and objective testing as all other lights that I have reviewed. At the time of review, this light retails for ~$35 USD (~$45 CDN).