- The Boring Stuff
- What comes in the box?
- Design & Construction
- Size & Measurements
- User Interface
- Modes, Brightness & Throw
- Runtime & Currents
- Driver & Regulation
- Emitter & Beam
- Carry & Ergonomics
- Batteries & Charging
The Boring Stuff
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What comes in the box?
The box is the typical thin cardboard box from Sofirn. It’s got a small foam pad on the bottom and the light was wrapped in bubblewrap. My box got squished during transport, but the light was fine so I suppose it’s adequate. I appreciate that Sofirn tries to keep the cost down here. The following items are included in the box:
- LT1S itself
- Battery (if you ordered it with a battery)
- User Manual
- USB A-to-C charging cable
- Spare O-rings
Design & Construction
LT1S is basically an LT1 with the battery tube chopped off and the port & button moved to the top. Instead of having four batteries on the bottom, LT1S has a single battery right in the middle. It makes LT1S significantly more compact and more stable and I love this design.
Build quality is good overall, about what I’ve come to expect from Sofirn. The anodizing is thick and even all over. There are no sharp edges. It’s well executed. The only complaints I have are that the bail is a little squeaky and gritty when you move it around, and that it’s hard to get the bottom cap threads started because there’s a big and beefy spring on the bottom. Mechanical lockout works great.
Size & Measurements
From left to right:
Sofirn BLF LT1
Generic “1000lm” 3xD cell lantern
|Battery Tube Diameter (internal)||22.0|
|USB Port Width||12.1|
|USB Port Depth||3.2|
|USB Port Height||11|
|Included Battery Length||70.8|
|Included Battery Diameter||21.8|
Weight without battery: 266g / 9.4oz
Weight with included battery: 339g / 12.0oz
LT1S foregoes the Anduril 2 user interface that contributed to LT1’s greatness, in exchange for a Sofirn-designed UI. That change was necessary to impliment some of LT1S’s new features like directional lighting and red modes. I’m not sure it was worth the trade though.
The actions are # of presses followed by a hold (H) or a release (C). So, “1C” is one click and release. “2H” is two clicks but you hold down the last one. A “+” on the end means the listed number of clicks or more.
|Off||1C||On (mode memory)|
|Off||2C||Turbo (not memorized)|
|Off||3C||Red (mode memory)|
|Moonlight||1H||Low (and cycle up modes)|
|On||1H||Cycle Modes (low-med-high-turbo, memorized) or Ramp Brightness|
|On||2C||Cycle direction (360, 180, 180)|
|On||2H||Tint ramp (memorized)|
|On||3C/3H||Red (mode memory)|
|On||4C+||Toggle smooth/stepped ramp|
|Red||1C||Return to previous state (off, or white)|
|Red||1H||Cycle Modes (low-med-high, memorized)|
|Red||2C||Red Blinkies (starts on 1hz Strobe)|
|Red Blinkies||2C||Toggle 1hz Strobe or SOS|
|Lockout||4C+||Unlock to on (mode memory)|
I’m torn about this UI. On the one hand, I understand the necessity to move away from Anduril 2 so they could add the directional and red light features. But, I’m not sure that those are worth giving up Anduril 2’s awesome features. In particular, I did miss Anduril 2’s sunset timer feature. 2C from on enables directional lighting instead of going to Turbo like most lights, and that consistently throws me off when I’m using LT1S.
Modes, Brightness & Throw
Disclaimer: I do not have the capability of measuring lumens from a lantern. Sofirn claims this lantern outputs 500 lumens on Turbo, so I’m basing all my white light measurements on that. They don’t make a red output claim, so my red measurements will just be relative output.
To my eye, red High mode looks about as bright as white Turbo mode, for what it’s worth.
|Level||Lumens (@ Turn-On)|
|Level||Relative Output (% @ Turn-On)|
Mode Spacing: Stepped mode spacing is great, but the smooth ramp has the same problem most smooth ramping lights do: it ramps too fast at the low end and too slow at the high end.
How does it compare to the official specs? I’m not equipped to do lumen measurements on a lantern.
Runtime & Currents
LVP: is present and shuts the light off when cell voltage reaches a critically low level. There are low voltage stepdowns that happen before that to warn you, and there’s the battery indicator on top too.
Current: I’m not equipped to do extreme duration runtime tests or extremely high current measurements. I only measure the currents on low modes and I calculate the estimated runtime of those modes based on the capacity of the battery or batteries I’m using for testing.
|Level||Current @ Tailcap (milliamps)||Estimated Runtime|
|Standby (parasitic drain)||0.170||3.4 years|
Driver & Regulation
LT1S uses a Buck driver. A Buck driver takes the 3-4.2V from the battery and efficiently converts it down to the 3V needed for the LED’s. That’s a significant improvement over LT1, which does not do any voltage conversion and therefore wastes that extra voltage. u/DerMaxPower over on Reddit did an awesome teardown if you want a closer look.
Regulation is not as good as I would have expected. Sofirn says LT1S is using a Buck driver and that should contribute to excellent regulation, but I’m not seeing it. It should not be pulling a lot of current on Turbo either, yet it’s affected by cell voltage similarly to a basic FET driver. This poor regulation doesn’t really affect usability, but it’s still a little disapointing.
Note: All regulation measurements are taken at turn-on so they do not reflect any thermal or low voltage stepdowns that may occur. A value of 0 indicates low voltage shutoff immediately upon activation. For this particular light, I found that Turbo and High modes stepped down very quickly to medium when I was testing with the cell at 3 volts.
Thermal regulation: is present and works well.
PWM: No PWM is visible to my eye. With an Opple Light Master III, I detected PWM on all modes, but it’s extremely fast (31.4khz) on all modes except moonlight (2.7khz)
Emitter & Beam
Sofirn says LT1S has “36 CSP1919 LED and 4 Red LED”. I’m afraid I don’t know the exact make and model of the LED’s, but u/DerMaxPower over on Reddit did an awesome teardown if you want a closer look at them.
With my Opple Light Master 3, I measured max CCT at 6000K with RA (CRI) at 100, and minimum CCT at 2700K with RA (CRI) 97. The Light Master is not a pro-grade piece of equipment so take those numbers with a grain of salt, especially the 100 CRI rating at 6000K.
The red light function is kind of neat. It’s very deep red and makes my Osram W1 Red look a little orange by comparison. The above photo just doesn’t do it justice. It’s good for signaling, not attracting insects to the light, and (supposedly) even red light therapy. A Reddit user suggested it would make a great bicycle tail light, which I find amusing. I really haven’t found it to be all that useful in my testing, and I could probably live without if it meant having Anduril 2 instead.
The “directional” light feature seems a bit gimicky to me. All it does is shut off half the LED’s. I was hoping it would boost output on one side while shutting off the other, and have some kind of baffles on the inside to prevent light from bleeding back around the diffuser, but no dice. This is really just useful for lessening glare when the light is sitting in front of you. It doesn’t work nearly as well as an LT1 with one of u/Adair21’s excellent 3D-Printed LT1 reflectors. Once again, this is a feature I could probably do without if it meant having Anduril 2 instead.
LT1S has an electronic switch position on top. It’s covered by a prominent, rubberized boot that’s easy to find and distinguish from the charging port cover, even in the dark. I love this switch location. It’s so easy to just press down with one finger. With LT1, I have to reach around the light and squeeze to press the switch so I don’t knock it over. That’s not terrible, but LT1S is noticeably easier to use. It’s not backlit like LT1, so there’s no always-on indicator to help you find it in the dark.
Carry & Ergonomics
LT1S fits in the hand nicely when carrying it. The bail works well too as a carry handle, despite its small size. LT1 is so heavy that carrying it by the bail can cause the bail to dig into your finger a bit and become uncomfortable. That’s not a problem with LT1S because it’s so light.
LT1S works great indoors and outdoors, but I think it pulls ahead of LT1 when used outdoors. With lighter weight it’s much easier to carry around, and with a lower center of mass it is far less likely to fall over if it’s on an uneven surface or if a gust of wind hits it. It’s easier to hang off flimsy tree limbs too, thanks to the lighter weight.
LT1S doesn’t have tripod mounting points like LT1 does. I find I don’t miss them. I do wish there were some strong magnets in the tailcap. It would be super handy just to be able to stick LT1S to any ferrous surface.
Batteries & Charging
LT1S uses a single 21700 battery in the center, instead of four 18650’s in the bottom like LT1. A Sofirn-branded, 5000mah, unprotected, flat top cell is optionally included. I don’t have any protected 21700’s to test with, but I don’t think they would fit due to length. I did test with an unprotected flat top 18650 cell and it works reliably. The fit of the included cell in the tube is delightful. There’s an air cushion when you insert the cell and it makes a nice “pop” sound when you remove it.
USB-C charging is included on LT1S. It’s full USB-C implementation with C-to-C cable support for charging and powerbank functionality. On my sample, charging stopped at 4.18V and took 2.5 hours. The majority of that time was spent on the last charging bar, so it appears to charge up to about 75% fairly quickly. The charging port cover is Sofirn’s typical cover for larger lights (same as LT1). It’s excellent and very secure.
One unique feature not found in a lot of enthusiast lights is a good battery level indicator. LT1S has four bright orange LED’s on top that indicate charging status and battery level. They come on when the light is turned on and stay on for several seconds, even after the light is turned off. I found I really enjoyed this feature. It’s much more intuitive and easy to use than a voltage readout and I love it. I wouldn’t mind having a voltage readout in the UI too though.
LT1S will run off USB power without a battery, but only A-to-C cables and below Turbo mode. I you use a C-to-C cable it will not work. If you use Turbo it will shut off. It works correctly if you have the battery connected, though.
Here are some lights in the same class and how they compare.
Sofirn BLF LT1: significantly larger, significantly heavier, significantly higher capacity, better user interface, no red, always-on backlit switch, tripod mounts, significantly more expensive
Sofirn BLF LT1 Mini: is basically a Sofirn IF25 with a diffuser on top and the Anduril 2 user interface. It’s been in development for over two years and still isn’t available at the time of writing, but according to the dev team, it should be released very soon.
Lumintop CL2: taller, narrower, less battery capacity, can use 14500 or AA cells, tripod mount, significantly more expensive, no powerbank function, worse user interface, fixed color temperature, no red
Olight Obulb MC: smaller, lighter, lower capacity, built-in battery, proprietary charger, magnetic, not as bright, cheaper, more light colors
This section is not comprehensive. If I didn’t include a particular light here, it doesn’t mean it’s bad or doesn’t deserve to be here. I simply cannot list every possible competitor.
LT1S is the best compact lantern I know of and I love it, even more than LT1. The construction, light quality, weight, and charging solution are all excellent. The brightness, runtime, and user interface are all solid too. Most importantly, the price is right at around $50. This is the lightweight, budget-friendly lantern to beat and is a fabulous addition to the LT1 line.
In the future, I would love for Sofirn to release an “LT1S Pro” with these changes: Anduril 2, Emisar/Noctigon flashing pads for firmware updates, an RGB backlit switch, a magnetic tailcap, warmer (2000K) warm emitters, and no red or directional modes.
Thanks to Sofirn for sending me this light for review!