[Review] Sofirn SD06 - good no-nonsense light even for non-divers

Review - Sofirn SD06


Sofirn wrote to me some time ago and asked if I would like to do a review of a new lamp. I hadn’t reviewed a lamp for a while and was interested in doing so.

This lamp was sent to me free of charge by Sofirn. I had no influence or other obligations apart from writing a review. Thanks to Sofirn for this!

About the SD06 is almost nothing known yet. It is a compact dive light with a single SFT-70 LED, a classic SMO reflector and a magnetically operated switch with integrated simple lockout.


The lamp was sent to me in a simple brown box. It is marked with a sticker for the LED type and other information.

It contained a lanyard and spare O-rings, a charger with USB-C cable, in which the supplied battery “just fits” - no wonder, according to the imprint on the back, this charger is not suitable for 21700 batteries, but only for 18650 or smaller. According to it’s label has 0.75 A charging current.

There was no manual inside the box, since it was a pre-release prototype. For mass-production there will be a manual included.

Appearance, quality and feel

The SD06 is kept very simple in overall design. The rather solid head has large cooling fins and the battery tube has individual recesses to ensure a better grip. This means that the lamp lies securely in the hand even when wet.

The wall thickness of the battery tube could be a little thicker. The curbs in the tube make it appear less solid.

The design is reminiscent of older Fenix lamps (especially the Fenix PD40 1st gen), especially on the lamp head, and looks great in my opinion. Simple and functional.

Tailstand is not possible as there is a large hole for a lanyard on the back.

The most striking feature is the protruding switch. Unlike most other lamps, this works magnetically: a Hall sensor is actuated by a magnet in the switch, which means that there are no holes in the housing and tightness is ensured. The high button enables another feature: the lamp can be put into lockout mode by turning it. This can also be done with one hand and works both when switched off and on, at any light level, and is a good idea to offer a simple lockout without multiple clicks or similar.

The protruding switch makes it easy to operate even when wearing thick gloves. The only disadvantage for some users could be the lack of a pressure point due to the magnetic actuation; as with some keyboard switches, the button can be pressed as far as it will go without there being a noticeable click.

The most important feature of a diving lamp is its water resistance. The lamp withstood all tests under water jets and submersion at depths of up to 1 m without any problems. Since I’m not a diver, I don’t have any other testing options available to me; however, like an Armytek Dobermann, it has two O-rings on the bezel and battery tube, which should ensure a diving depth of at least 50 meters.

Although the O-rings have been greased, the thread should be regreased before a dive.

Unfortunately, the front glass fogs up from the inside after use in very cold water. This disappears again after a while, but can change the beam depending on the intensity.

The SD06 is not easy to disassemble. The bezel and driver is glued.


Three light levels are available. The SD06 is easy to operate:

  • Short click of OFF: Start in the last light level (mode memory)
  • Long click of OFF: No reaction
  • Short click on ON: Switch through the light levels
  • Long click on ON: Switch off lamp
  • Turning the button to the right: Lockout (also possible when the lamp is switched on)
  • Turn the button to the left: Cancel lockout

There are no flashing modes and no hidden menus. There is mode memory in all light levels, i.e. the last light level used is saved and called up when the light is switched on again.

However, I would have two suggestions for improvement here:

A proper low mode (3-5 lm) should definitely be provided, which can be accessed via the unassigned “Long press OFF” function. This ensures that such a mode is not in the normal switching sequence what can be useful while diving, but can be reached safely and without previous glare by briefly switching off and then pressing and holding. This can be helpful if you need light at close range after a dive on a less well-lit deck, because at the current lowest level, the lamp is far too bright at close range due to its rather concentrated light beam.

In addition, the current lowest light level of 260 lm should be reduced to around 170-200 lm to ensure a greater difference to the higher light level, especially when the battery is half empty.

With this adjustment, the lamp would also be suitable for everyday use outside of diving.


A 21700 with Sofirn branding is supplied. It is specified with 5000 mAh. The discharge test with a Vapcell S4 v2 at 1 A shows 4975 mAh as result, which is good.

Other unprotected 21700s and very short protected ones will fit, but a Fenix ARB-L21-5000 (76 mm incl. buttontop) is too long. There are springs on both sides, which give a certain amount of leeway in length and effectively prevent the power supply from being interrupted in the event of an impact. A 21700 should not be longer than 74 mm; some protected 21700s could still fit.

If necessary, 18650s can also be used without an adapter: simply insert, screw shut and you’re done. The capacity is lower and the runtime will therefore be significantly shorter, and the output may also be lower.


A cool white Luminus SFT-70 LED with 70 CRI is used. This 6 V class LED does not have a dome and normally provides a good beam, even when using smooth (SMO) reflectors. The SD06 is equipped with just that.

The tint is slightly green in the low power range, but pleasantly white at higher light levels, changing to a clearly visible blue at the highest level. The green tint at low operating current is a known problem with Luminus LEDs and can only be avoided by using LEDs with a certain color binning (as far as possible); see also my review of the Luminus SFT-70.

A neutral white LED (5000-5500 K) with a slightly negative duv would also make the SD06 suitable for underwater photography, at least with a suitable diffuser.

The front glass has an apparently high material thickness (2-3 mm), but is not AR coated.

Running times

Running time test in cold water (immersion conditions)

Used luxmeter: Benetech GM1020 in data-logging mode

It is clear that the focus here was on long runtimes, something that is essential when diving, as it is impossible to change the battery under water and the energy budget therefore plays an extremely important role.

When starting at the highest level, it regulates back to the lowest level relatively quickly. This does not happen smoothly, but suddenly. It is then still possible to switch up to the highest level without any significant loss of power. The highest level should therefore be seen as a kind of “turbo” for very limited periods of use. The step-down is presumably always time-controlled.

From a certain battery voltage (3.6-3.8 V), the highest level only delivers around 1600 lm. Only when the battery voltage continues to drop can the highest level no longer be activated at some point.

The middle level is fully regulated. After around 45 minutes, the luminous flux decreases in a controlled manner and then remains at a level around 30 % lower for a further 60 minutes. After that it steps down again.

When the battery is low, the lamp flashes at regular intervals and further reduces the luminous flux. This is seen in the chart after around 180 minutes, which is indicated by these dips. At this point at the latest, you should either abort the dive or use a spare (backup) lamp. At some point the lamp switches off, but can still be switched on at the lowest level before this option also fails at some point. The battery has 2.7 V at this point, and light can then only be produced with the SD06 for several seconds at a time when the button is pressed.

Runtime uncooled

The behavior at Turbo does not change, there is still a hard stepdown.

At the original level, the SD06 reaches a surface temperature of around 41 degrees, which is fine. There is no risk of burns. This means that the middle stage can be operated continuously. In the runtime chart there is a slight drop due to rising temperature.


The lamp heats up quickly on the highest setting. It reduces the maximum luminous flux before the surface temperature becomes too high.

The following measured values were taken with a Samsung INR21700-40T @ 4.18 V (Charger: Vapcell S4+ 2000 mA charging current), half-full @ 3.6 V

An integrating sphere was used.

Mode Light flux Brightness
Turbo (battery full) @ 5 sec 3053 lm 62400 lx
Turbo (battery full) @ 30 sec 2775 lm 56700 lx
Turbo (battery half-full) @ 5 sec 1602 lm 32600 lx
Mid @ 5 sec 982 lm 21300 lx
Mid @ 30 sec 981 lm 21300 lx
Low @ 5 sec 258 lm 5530 lx
Low @ 30 sec 258 lm 5530 lx

Beam quality

The beam is very good. There are no color distortons in the spill or around the spot; rings are only visible on the whitewall if you look closely.

Generally speaking, the SD06 is more of a thrower; due to the relatively wide spill, it can also be used at close range in principle, although a significantly dimmer light level should be provided for this.

Due to the lack of a low level, the lamp is too bright even at the lowest level at close range.


The SD06 is specifically marketed for divers. However, I also see it as a simple “no nonsense” lamp for everyday use - a lamp that simply does its job. Simple operation without configuration options or flashing modes, no tactical, futuristic design, and full waterproofness makes it interesting for me as an everyday lamp. The switch, which can be operated with thick gloves and has a very simple lockout, can also offer real value.

However, I strongly suggest to add a “real” low in the 3-5 lm range for the release version, not only for everyday purposes, so that the lamp can also be used sensibly at close range, which is basically impossible in the moment. In addition, an LED with a neutral white color temperature without a greenish tint and low luminous flux should be considered so that the lamp can also be used for underwater photography (possibly with a diffuser).


  • Simple design
  • Battery and charger included in box
  • Switch with very simple lockout
  • long runtimes
  • very simple operation with no flashing modes (strobe etc.)
  • fully waterproof
  • good beam without annoying artifacts


  • lowest light level much too bright, therefore hardly or not at all usable at close range
  • Greenish tint at the lowest level
  • No neutral white option and/or high color rendering available

Hope this review is useful for you! :slight_smile:

Best regards, Dominik

10 Thanks

Thanks for the review!
I just skimmed it now, but I plan to read it in-depth later. :grin:

2 Thanks

That’s a really interesting switch. Makes me curious to try it out now.

1 Thank

Wow! Excellent review. Thanks for the great job.

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With the integrated lockout it is quite interesting and very usable. There is nothing really to say about, the switch just works. With thick gloves no problem at all. The light does not roll away since the switch protrudes a lot and stops rolling at some point.

Turbo makes no sense to drop to low level though. I really hate Sofirn’s coding at times.

2 Thanks

I have this light and I’m going to review it in due time.
Turbo overheats pretty quickly, so I use the light on Medium, but, yeah, the stepdown for Turbo is extreme. :+1:

Weird to have such a strong dropdown, if light is meant to use underwater. Cooling shouldn’t be a problem.

How would you compare it with Sofirn SD05? A common complain was that the rotary switch was good, but could turn the light on in the bag as there was no lock. On the other hand the SD5 was praised for its flat regulated outputs - the SD6 seems to be doing something different. Are the beams comparable?

I don’t have the SD05, so I cannot compare them.

But I suggested some changes to Sofirn for the SD06, like adding a fourth moonlight mode (3-5 lm) and avoid stepping down from turbo to low. Hopefully they will change this since these are the only things I really critize.

Also I wonder why the aren’t using AR coated glass for the SD06 since the SD05 seems to have it.

1 Thank

Thank you very much for your great review of SD06 and your advice, that’s very helpful for us! :wink:
Do you interested in comparing SD06 with SD05, we can send you one sample :smiley:

2 Thanks

If you want I can do this!

Great~! We will send you the track number via private as soon as it is sent out :smiling_face_with_three_hearts:

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It would appear that the SD06 is the bigger brother of the newly-released SD03:

Based from your review pictures of the SD06, they sport similar button/magnetic control.

I ordered the SD03 to try out, which arrived today. The box did not include a manual, so I had to check your review to see if the SD03 operates similarly. (it appears to operate exactly the same as the SD06 which was mentioned above).

So the light can be turned ON, and then switched to the Locked position (which means, the light cannot be turned off by pressing the button, unless selecting it to the Unlocked position).

From what I notice, the differences are that whereas the SD06 uses SFT70 and 21700 battery, the SD03 instead uses SFT40 5000k and 18650 battery. Operation-wise, they appear to be the same as mentioned in the SD06 review.

I have received the Sofirn SD05, thank you for that, Sofirn! :slight_smile:

In direct comparison with the SD06, it is immediately apparent that these two lamps differ considerably. In principle, they are completely different products and not really comparable at all (except for the designated target group of divers). Also the performance differ at some point.

Both lights tested with Samsung INR21700-40T @ 4.18 V (charged 2 A in Vapcell S4+)

SD05 SD06
Turbo 5 sec. 4153 lm // 31500 lx 3053 lm // 62400 lx
Turbo 30 sec. 3869 lm // 29200 lx 2775 lm // 56700 lx
Mid 5 sec. 1056 lm // 9030 lx 982 lm // 21300 lx
MId 30 sec. 1044 lm // 8980 lx 981 lm // 21300 lx
Low 30 sec. 271 lm // 2240 lx 258 lm //5540 lx

The performance of the SD05 is much better as stated. Furtermore, it is much, much better as in other reviews! For Turbo (highest mode) I got insanely high 4153 lm after 30 sec. which is over 30 % higher as stated by Sofirn. The head heats up really quickly also, which I not expect for a mass-production light.
After around 15 sec. on highest mode the temperature raise above 40 °C.

To check this absurd high reading for plausibility, I checked the current of the SD05 on highest mode with a clamp meter. I got 13.7 Amps, which matches the light flux.

Biggest differences design-wise:

Operating concept:

  • SD05: Magnetic rotary ring
  • SD06: Magnetic switch with built-in rotary function for lockout


  • SD05: Floodlight, OP reflector. Cree rainbow
  • SD06: Thrower, SMO reflector. Clean beam


  • SD05: Cree XHP50.2 HD (domed), ice-cold-white, no significant tint-shift
  • SD06: Luminus SFT-70 (domeless), cool white with slight green in lower modes


  • SD05: More aggressive, with a lot of edges
  • SD06: More elegant

Included battery:

  • SD05: 4000 mAh 21700
  • SD06: 5000 mAh 21700

I noticed one important thing relatively quickly during the test: the battery tube of the SD05 is thicker and feels more solid. This is also reflected in the weight, especially as both battery tubes have similar external dimensions. I strongly recommend opting for more wall thickness here, as this significantly improves the overall feel and quality impression.

The regulation is also different. The SD05 regulates down from Turbo to the High level, from around 4100 lm to 1500 lm. The SD06, on the other hand, drops directly from Turbo to Low! The comparison makes it all the more obvious how unnecessary this design decision actually is and that it urgently needs to be revised in all new SDxx lamps.

The operating concept and beam in particular make these lamps different. With a modern LED with low luminance (XHP50.3 HD or similar) without artefacts in the beam and a low mode of around 3-5 lumens, the SD05 would be a very good lamp for close range also for non-divers. The SD06 has a longer range thanks to the domeless SFT-70. The missing step in the 3-5 lm range for immediate close range is missing on both models, which makes use of the light in close range very difficult.

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This might be due to the light being designed for “water-cooling”. I guess it should be more thermally stable if submerged.

Maybe (but if it relies on water cooling this is not a good design, it has to be as good for use on land), but this not explain the extremely high performance.

Thx dear.
I’m always asked why there aren’t enought diving headlamp for who want both hands free during immersion.
Does a special headband equipment are required to avoid lost it?

wowww excellent comparison :beers:

1 Thank

May I know do you like our upgrade in switch?