[Review] Sofirn SF47T

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Lux-Perpetua
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[Review] Sofirn SF47T

Hello everyone,

Sofirn kindly sent me a free sample of their brand new product SF47T in return for an honest and unbiased review. Thanks a lot for the nice opportunity.

Disclaimer: I did not receive any kind of compensation except for the light in return for this review.

For those of you who like to read the German version, I have also published my review on TLF.

https://www.taschenlampen-forum.de/threads/review-sofirn-sf47t.80580

Please also have a look at Jacob's ("Funtastic") informative and interesting video review of the SF47T. I share a lot of his conclusion about this flashlight.

https://youtu.be/YKYxyXUSyCA

 

What's special about Sofirn's SF47T?

Launching the SF47T ("T" for thrower), Sofirn finally made a successful step up to Osram LEDs. As a result, we get to see an interesting and sleek midsize thrower flashlight for searching, hunting and many more applications. It is the right tool if you need beam distances up to 1,100m ANSI, i.e. 300m to 400m actually visual range. Prominent features of the SF47T are the 7A constant current buckdriver, the 21700 format, the utilization of Osram's latest KW CULPM1.TG ("Boost HX") emitter as well as a significantly improved thermal regulation (ATR) - more about this later on. Like many similar tactical thrower flashlights with dual switch layout (mechanical tailclicky and electronic side switch), the SF47T comes with a classic user interface providing two mode groups for individual needs.


Some specifications:

  • Dimensions: 247.5mm (length) x 55mm (head diameter)
  • Weight: 315g w/o batteries
  • Emitter: Osram KW CULPM1.TG ("Boost HX"), 6500K CCT
  • Max. output: 1,500 Lumen (manufacturer's rating)
  • Max. runtime: 41 days (Moonlight mode)
  • Peak distance: 1,100m (manufacturer's rating)
  • Peak intensity: 303.750cd (manufacturer's rating)
  • Driver: 7A 2S constant current buckdriver
  • Battery: 2x 21700 lithium-ion battery in serial connection (8.4V)
  • Water resistance: IPX-8 up to 2m
  • Impact resistance: 1m
  • User Interface: tactical dual switch UI with stepped modes (Moon, Low, Medium, High and Turbo as well as Strobe/SOS/Beacon)
  • Mode Memory: Yes (standard modes Low, Medium und High only)
  • Low voltage protection
  • Reverse polarity protection
  • Thermal regulation "ATR"

Where to buy? (no affiliate-links):

>>> Amazon US <<<

>>> Amazon DE <<<

>>> Sofirnlight.com <<<

>>> AliExpress <<<

 

Please note that Sofirn frequently promotes discounts and coupons on BLF, so I recommend checking for these before you hit the purchase button. Wink

 

Unboxing

Remarkably, Sofirn updated their cardboard box design. It now features the Sofirn logo and slogan as well as two QR codes to quickly access their websites on AliExpress, Alibaba and Sofirnlight. I like the fact that their packaging is more or less environmentally-friendly without any plastic blister that painfully cuts into one's hands.

 

 

If you purchase the kit-version you get apart from the light: a simple 2-bay charger (5A 2A input, 1A output each), a microUSB cable, a lanyard, the multi-language manual and two unprotected 21700 5000mAh batteries with Sofirn branding.

 

 

SF47T follows the typical shape and concept of other tactical dual switch flashlights, e.g. SP70, Jetbeam BC40 Pro, Nitecore MT42, Klarus XT32, Acebeam T21 or Fenix TK47. Sofirn however uses the new advanced 21700 format which benefits from more capacity/runtime but also from a better tactile handling, a better ratio between head and tube as well as a better weight balance in one's hand.

Looking at the head we see a slightly crenelated bezel for tactical purposes. Sofirn refrained from using stainless steel here. On the plus side it will not distort the beam by unwanted artifacts. There's a deep SMO reflector with Osram's latest "Boost HX" emitter in the center. This new generation emitter is a bit advanced over its predecessor "White Flat 2" (KW CSLPM1.TG) as it uses a 4040 footprint, enabling easier focusing and better thermal properties at high currents. Talking about focusing, Sofirn did quite a good job here but still there's some room left for slightly better centering in order to get optimum peak intensity. On a white wall I see some little blurring of those four overlapping ovals around the hotspot. Outside however you will not notice any of this.


 

The flashlight can easily be dismantled into three parts: head, tube and tailcap. Threads are well-made and run smooth but came dry as a desert from factory. I fixed this with some lubrication right away. The tube features a knurling that does not cover its full length. Thus, secure tactile handling is given on the rear end, only. This is a bit odd as it takes one's hand to grab the anterior end of the tube to operate the side switch. Maybe Sofirn can improve this minor imperfection with the next revision. The tube can only be used in one direction as both ends feature different threads/wall diameters. Protected button top 21700 batteries cannot be used as the maximum length for both batteries must be 145mm or less. As a matter of fact, there's quite some spring tension already when using two flat top batteries. More about this later.

 

 

Having a brief look at the driver, I noticed that Sofirn did not use their traditional linear / FET drivers but a more efficient 7 amps buckdriver with constant current regulation and improved thermal regulation. A very wise choice in my humble opinion, as you may see on the runtime analysis later. The flashlight's head features a rather large spring whereas the tailcap comes with dual springs for better current flow.

 

 

A closer look at the head reveals that Sofirn invested a lot of efforts here. The protruding side switch is more easily to find in darkness and has an improved pressure point. It still feels a bit too soft to my mind but it is much better than those from previous generations. All heat fins are perfectly deburred and feel smooth. The anodising is one of the best I have ever seen in Sofirn flashlights.

 

 

Besides these many positive observations I also noticed a lot of dust in the reflector of my sample. This does not seem to be a single incident since Jacob's review sample looked very much the same. Anway, it is probably an optical imperfection only since this amount of dust will not have any severe impact on the beam quality and peak distance.

 

 

A closer look at the batteries

Along with the kit-version you get two 21700 5000mAh batteries that feature Sofirn's branding. This battery model is quite new in Sofirn flashlights and it is also being used by Wurkkos for their new TS30S powerhouse. Underneath the shrink wrap is a Lishen LR2170SD cell which has a protruding positive terminal and a recessed ring in the negative terminal. Its performance can be compared with Samsung's 50E/50G. Sofirn did a reasonable decision in choosing this battery for SF47T.


The most important specs:
Diameter: 21,7mm ± 0,2mm
Length: 70,9mm ± 0,2mm
Weight: 72g ± 4g
Nominal capacity: 5000mAh at 0.2C discharge current
Minimum voltage: 2.50V
Maximum voltage: 4.20V ± 0.03V
Standard charge current: 0.2C (1000mA)
Maximum charge current: 0.7C (3500mA)
Maximum discharge current: 2C (10000mA)
Impedance: ≤ 30mΩ

 

I measured an impedance of 10mΩ (1kHZ AC). The resting voltage was at 3.59V when I unboxed the light - very good. Both batteries differ about 100mAh in total capacity; voltages differ about 0.03V after discharging them in the flashlight. This is quite acceptable for operation in serial connection.


Remark: In serial connection, always use batteries as a pair and do not mix them with other batteries.

 

Since this battery comes with a protruding positive terminal, two of them can be driven in serial connection in a row. The positive terminal of the anterior battery was already slightly dented when I received the flashlight. Hence, there is a lot of spring tension. Many standard 21700 with flat top could have problems in making contact with each other. I recommend placing a (flat!) magnet as a bridge in between. But stay alerted about the high spring tension. I rather recommend buying the kit-version and use the batteries supplied with the light.


 

Size comparison

from left to right: Sofirn SP70, Sofirn SF47T, Sofirn C8F, Sofirn SC31 Pro, Wurkkos FC11 with 18350 tube

 

 

User Interface

Like many other tactical models with dual switch layout, SF47T comes with a classic UI. You can select from two mode groups called "Outdoor" and "Tactical". Both mode groups have dedicated stepped modes in common. Unlike other Sofirn flashlights like SP70 or C8F this one does not have any standby functionality, i.e. it is impossible to turn on/off the SF47T via side switch.

 

Group 1 - Outdoor (default)

Light is... Action for tail switch Action for side switch Result
OFF Tap and hold   Momentary light (mode memory from L/M/H)
  Double-tap and hold   Momentary light (Turbo mode)
  Press   Turn on with the selected brightness mode
  2. Press 1. Hold Moonlight mode, consecutive clicks to cycle L/M/H
ON   Click Cycle standard modes (L/M/H)
    Double-click Turbo mode, single click to return to previous standard mode
    Triple-click

Tactical strobe mode, consecutive double-clicks to cycle SOS/Beacon, single click to return to previous standard mode

    Hold for 3 seconds

Change to Tactical group (light turns on in Turbo mode)

 

Group 2 - Tactical

Light is... Action for tail switch Action for side switch Result
OFF Tap and hold   Momentary light (Turbo mode)
  Double-tap and hold   Momentary light (Strobe mode)
  Press   Turn on with the selected brightness mode
  2. Press         1. Hold Moonlight mode, consecutive clicks to cycle Low / Turbo
ON   Click Cycle standard modes (Turbo / Low)
    Double-click Tactical strobe mode, consecutive double-clicks to cycle SOS/Beacon, single click to return to previous standard mode
    Hold for 3 seconds Change to Outdoor group (light turns on in Low mode)

 

Runtime and thermal analysis

As mentioned before, the SF47T uses a buckdriver with constant current regulation. This kind of driver is the right choice for new generation LEDs like Osram's Boost HX since they efficiently convert the (too high) battery voltage down to a much lower LED voltage (Vf). A linear driver would burn the excess voltage into heat, subsequently leading to overheating driver components and finally forcing the light to step down. Those 7 amps were chosen wisely. However, 8 amps would have been the icing on the cake with regard to Convoy's L21A and the improved thermal design of Osram's Boost HX.

 

The flashlight maintains its full output for about 7 minutes before thermal regulation (ATR) is triggered at approx. 50°C surface temperature. Afterwards, the output is more or less stabilized at 70% of turbo mode (I guesstimate about 750-850lm) for almost exactly 2 hours. Meanwhile, its temperature is maintained at approx. 54°C. Looking at the fluctuations of the lux meter graph I can see that ATR is always triggered to keep the temperature at that level, resulting in brightness fluctuations of about 10%. The human eye however will not notice these small increases and decreases in brightness. In comparison to Sofirn's SP33 V3 with its mediocre and way too aggressive thermal regulation I can confirm that Sofirn's engineers did a great job improving their ATR algorithm.

 

 

Beamshots

I must confess that due to legal restrictions in conjunction with the pandemic I was unable to use my tripod and camera. Please excuse the modest image quality of my smartphone camera. Nevertheless, I hope you get an idea how the beam looks like. Wink

 

 

Conclusion & Verdict

With their new SF47T Sofirn accomplished to creating a compact, powerful and affordable midsize thrower. For a budget of 60 Euros you get a lot offered in return, especially if you choose to buy the kit-version. Its significantly improved thermal regulation and its efficient buckdriver are just two of many highlights of this model. Those who look for constant light output for up to 500m actual visual range with some useful spill around the hotspot will certainly be pleased with the SF47T. Workmanship is on a high level except for a few things that I would like to see improved.


I do see some potential for improvement in following aspects:

  • Dust should not belong in a reflector even though it will not have that much impact on output and beam quality.
  • The tube's knurling could be applied to its full length for better tactile handling, especially with regard to the side switch.
  • Threads are dry but could be lubricated by factory already.
  • Having the chance to turn on/off the light via side switch ("standby mode") would be convenient, at least in my humble opinion.
Edited by: Lux-Perpetua on 02/07/2021 - 13:12
Rusty Joe
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Nice! Thanks!!!

weklund
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Excellent review. As I own this light I can attest to it’s bargain point for what’s included. I also agree with your statement.

“Having the chance to turn on/off the light via side switch (“standby mode”) would be convenient, at least in my humble opinion.”

Very annoying to not have On/Off from the side switch.

Overall I am very happy with the light.

... Happy Landings ...

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Thanks for the review. This light would be great if they added some things to the ui along with all the other things mentioned.
In general mode, I think a double click from off should have gotten to turbo. But instead it does nothing. In tactical mode it does strobe.
And I really think turbo mode should be access in the mode selection as well. This way it can be memorized so next time I turn it on, it’ll be on turbo already.

smuxy
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Thanks for the review! I have the light and I find it great. Could anyone recommend a simple 2 bay charger for the 21700 batteries like the Sofirns? They don’t fit into my litokala 500.

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Double click from off goes to turbo. First click has to be half-click.

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Lux-Perpetua wrote:
I must confess that due to legal restrictions in conjunction with the pandemic I was unable to use my tripod and camera.

Wait… what?? How would a tripod/camera be… “illegal”?

 

I’m wondering, though, how people are handling the tailswitch on such a long and nose-heavy light.

Needs to be a 2-hander? Ie, hold the light with one hand and work the tailswitch with the other? Or have really strong wrists and grip to hold the light by the very end while working the tailswitch with the thumb?

I can’t even work my SP31Av2 with one hand, if trying to change modes with the sideswitch but also work the tailswitch, not without changing my grip entirely to work one switch or the other. I’m puzzled how one is supposed to work a way longer light like the ’47.

The C8F lets you have a “soft” off/on with the sideswitch, if I recall right. Wondering why soft-off went away on newer lights…

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

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blueb8llz wrote:
I think a double click from off should have gotten to turbo. But instead it does nothing. In tactical mode it does strobe. And I really think turbo mode should be access in the mode selection as well. This way it can be memorized so next time I turn it on, it’ll be on turbo already.

As shown in my youtube review, a double half press and hold from off, activates Turbo.

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Lightbringer wrote:
I’m wondering, though, how people are handling the tailswitch on such a long and nose-heavy light.

Needs to be a 2-hander? Ie, hold the light with one hand and work the tailswitch with the other? Or have really strong wrists and grip to hold the light by the very end while working the tailswitch with the thumb?

I can’t even work my SP31Av2 with one hand, if trying to change modes with the sideswitch but also work the tailswitch, not without changing my grip entirely to work one switch or the other. I’m puzzled how one is supposed to work a way longer light like the ’47.

The C8F lets you have a “soft” off/on with the sideswitch, if I recall right. Wondering why soft-off went away on newer lights…

It’s not too bad for switching it on, but it’s certainly not ideal. As a store I decided not to stock this model.

I find this Osram led a little odd in this kind of light, usually a tactical model needs a wider beam using the XHP35 HI or SST40 etc, the Osram’s are really just for dedicated throwers. I used to work security, guarding a bank, on 12 hour night shifts and I’d never use a light with such a narrow beam.

I almost felt like there should be a shoulder strap attachment on the head, for those who don’t want to always put it into a holster, it’s quite long.

I’d like to see Sofirn

- install an SST40
- make a short version

Would a standby from the side switch mess up activation at the tail? It is a tactical model and you need instant on, not switch on in standby.

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

YouTube channel – https://www.youtube.com/channel/UCIUWi2vYp4CWrRkOJM70t_w/videos (Demos for my customers, and reviews)

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Lightbringer wrote:
Lux-Perpetua wrote:
I must confess that due to legal restrictions in conjunction with the pandemic I was unable to use my tripod and camera.
Wait... what?? How would a tripod/camera be... "illegal"?

Neither tripod nor camera are illegal - but - in Berlin, Germany you currently need to have „good reasons“ to go outside. That explicitly rules out going after one‘s hobbies. If I was caught in the middle of taking beamshots out in the lonesome wilderness the police could have fined me with at least 50 Euros.

Lightbringer wrote:
I'm wondering, though, how people are handling the tailswitch on such a long and nose-heavy light. Needs to be a 2-hander? Ie, hold the light with one hand and work the tailswitch with the other? Or have *really* strong wrists and grip to hold the light by the very end while working the tailswitch with the thumb? (...)

It‘s not so bad. The light is not as top-heavy as the SP70 with its big reflector.

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Funtastic wrote:
(...)Would a standby from the side switch mess up activation at the tail? It is a tactical model and you need instant on, not switch on in standby.

Standby should not interfere with the activation at the tail. The mechanical tail switch needs to be activated first before you can turn the flashlight into a soft-off („standby“) mode via side switch. I would recommend some changes in the side switch UI, e.g. Hold to cycle modes and Click to use soft-off / soft-on. Unlike C8F and SP70 I would however like the flashlight to always light up when pressing the tail switch.

I am not sure how far Yakorsei is with their RD12 model yet. I recommended them to have this soft-off feature in their UI. Maybe I get to review this model anytime soon after CNY.

https://yakorseilighting.com/products/yakorsei-rd12-hunting-flashlight

 

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Lux-Perpetua wrote:

Funtastic wrote:
(...)Would a standby from the side switch mess up activation at the tail? It is a tactical model and you need instant on, not switch on in standby.

Standby should not interfere with the activation at the tail. The mechanical tail switch needs to be activated first before you can turn the flashlight into a soft-off („standby“) mode via side switch. I would recommend some changes in the side switch UI, e.g. Hold to cycle modes and Click to use soft-off / soft-on.

I am not sure how far Yakorsei is with their RD12 model yet. I recommended them to have this soft-off feature in their UI. Maybe I get to review this model anytime soon after CNY.

https://yakorseilighting.com/products/yakorsei-rd12-hunting-flashlight

 

 

...but, the C8F, SP70 etc will start in standby if it was first turn off with the side switch. This would be an issue with a tactical model.

I signed up for a review unit but unsure if they'll send it. I'd like to make a video for hunters since I am on a farm. I find the reviews from Flashaholic channel are useless since beamshots on buildings aren't that useful in real world use.

I might email Kingkong Kim (unusual name) and see if they'll send me one. I have said I wanted to be a distributor if they improved the UI and thermal regulation for the GD12.

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Funtastic wrote:

...but, the C8F, SP70 etc will start in standby if it was first turn off with the side switch. This would be an issue with a tactical model. (...)

Correct, that’s why I would ask them to change that. Tapping or pressing the tail switch should ALWAYS light up the flashlight and override any soft-off via side switch, at least in the Tactical mode group. TL;DR, soft-on works only from soft-off, i.e. tail switch must be activated first.

I can try to remind „Kingkong Kim“ to send you a sample. He once asked me about good video reviewers and your name was one of the first that came into my mind. Wink I did not talk to him for a while. Now, he‘s probably in the middle of CNY holidays. Last information I got was the RD12 is still in development.

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Lux-Perpetua wrote:

I can try to remind „Kingkong Kim“ to send you a sample. He once asked me about good video reviewers and your name was one of the first that came into my mind. Wink I did not talk to him for a while. Now, he‘s probably in the middle of CNY holidays. Last information I got was the RD12 is still in development.

I'd appreciate that, but I will contact them anyway if I remember.

I now have the same camera set up as Matt Gill (Flashaholic) so the footage is decent. The only downside is I'm limited to 1080p as rural internet speeds are slow, no 4K unfortunately

Texas Ace Lumen Tube calibrated with maukka lights

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I have a comparison video I’m currently editing of the Maxtoch Shooter 2x, Convoy L21A CULPM1, Astrolux FT03, Convoy C8+ with CSLNM1, CSLNM1 Green, and CULPM1. Should be finished in a day or two

Texas Ace Lumen Tube calibrated with maukka lights

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Any chance of getting a comparison set of beam shots with this light vs. an SP70?

As others have said, the SP70 with the ability to turn it off using the side switch is really nice on a longer light.
I can see me going wild clicking the side switch trying to turn it off in a stressful situation.
This is why I prefer the SP70 over the L6 Convoy.

Is it possible to remove the front bezel to clean out the shmoo on the inside? Both my SP36s needed cleaning due to some sort of deposit on the inside of the lens. Looked like something out-gassed and left a residue behind.
The SP36 just unscrews, no glue. But mine were hell for tight on there.

Great review, Thanks!
All the Best,
Jeff

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jeff51 wrote:
Any chance of getting a comparison set of beam shots with this light vs. an SP70?

As others have said, the SP70 with the ability to turn it off using the side switch is really nice on a longer light.
I can see me going wild clicking the side switch trying to turn it off in a stressful situation.
This is why I prefer the SP70 over the L6 Convoy.

Is it possible to remove the front bezel to clean out the shmoo on the inside? Both my SP36s needed cleaning due to some sort of deposit on the inside of the lens. Looked like something out-gassed and left a residue behind.
The SP36 just unscrews, no glue. But mine were hell for tight on there.

Great review, Thanks!
All the Best,
Jeff

Sofirn provides a comparison shot on their SF47T page to the SP70. PHOTO Really noticeable spill difference. Maximum beam reach is allegedly 1000m (SF47T) to 800m (SP70), which shouldn’t matter all that much. But the SP70 weighs 1.38 lbs, while the SF47T weighs 0.7 lbs, and the SP70 head is 3.55 in to SF47T head at 2.16 in. That’s quite a difference and may be a factor if you’re taking this on a hike.