Today I’m reviewing the updated version of Sofirn’s SD05 flashlight. This is my first diving light and my first light with a rotating switch.
About the light
The SD05 is advertised as a diving light and is waterproof to 100m. It uses a 6000K (cool white) CREE XHP50.2 LED and puts out 3000lm on high. It takes a single 21700 sized cell, though will work with 18650 cells too.
You can buy the Sofirn SD05 on Amazon UK (£39.99, with cell and charger). Only an older version of the SD05 comes up in a search on Amazon US at the moment but the new one may be available when you’re reading this. It’s also available from Sofirn’s shop directly, either just the light or with cell and charger.
The original SD05 version stepped down from high after 3 minutes to keep the light cool, which isn’t so useful in a diving light. Sofirn listened to customer feedback and have released a new SD05 flashlight without the timed step down. The old version was listed at 2550 lumens and the new one claims 3000 lumens. When purchasing, make sure you get the new version, as some places still have the old in stock. Sofirn could have called the new one something else to help differentiate the 2 versions, such as SD05B.
There don’t seem to be any different LED options available.
Sofirn SD05 specs
|Emitter||Cree XHP50.2 LED, 6000K-6500K|
|Waterproof||IPX8, underwater 100 meters|
|Case Material||6061Aircraft-grade aluminum alloy|
|Power Source||1* 21700 battery|
|Net weight||120g (Excluding battery)|
I measured 119g without the cell and 187g with
|Working voltage||3- 4.5V|
|Dimension||119mm(length) × 37.5mm(head)|
I measured 119.7mm length, 37.5mm head and 29.0mm body diameter
The physical light
What’s in the box
Sofirn picked a plain cardboard box for the SD05. They seem to use this for their larger packages and have a nicer printed cardboard for their smaller ones.
In the box you’ll find:
- SD05 light
- 21700 cell
- Sleeve for 18650 cells
- 2 o-rings
- Micro USB cable
- USB charger
Appearance and quality
The SD05 has 2 O-rings at each end of the body tube to help with waterproofing. There’s 2 o-rings, 1 either side of the glass too. The box only comes with 2 spares but they’re easy to source if you need new ones.
The body tube is asymmetric, with much thinner threads on the head end (the same size as the bezel threads). I have no idea why they went with 2 thread sizes.
There isn’t any knurling, aside from a few bumps.
The SD05 has fairly thick springs at either end. This means it can take a range of different length cells and doesn’t flicker when it’s shaken.
The SD05 takes a 21700 cell, so is a bit bigger than most 18650 lights. Here’s the Sofirn SD05 next to an Emisar D4 (18650 cell), an Imalent MS03 (21700 cell) and a Nightwatch NSX3 (21700 cell). It’s nicely sized and comfortable to hold.
Carrying and everyday use
The SD05 comes with a standard lanyard, which is attached at the tail at the side (so it can still tail stand). There’s no clip but the light’s probably a bit big for most pockets anyway.
Underwater use, swimming
This is a new section in my reviews. I have a few lights that are IPX8 rated (so should be waterproof enough to be in water for 30 minutes at 2 meters depth) but don’t have any that are designed primarily for use underwater. I’m by no means a diver (I’ve never been anywhere near the 100m depth rating of the SD05) and I rarely go in water when it’s dark or deep enough to need a flashlight.
I wanted to put the SD05 through its paces though, so I took the SD05 to a nearby river.
I’d normally be nervous putting electronics in water, especially a river that was so murky. The SD05 did fine though and allowed me to see fish and stay out in an inflatable dinghy well past dusk. I have to admit, having a flashlight underwater is pretty cool at night. The 3000 lumens allowed me to see over 2 meters through the cloudy parts of the water. I lowered the light on a string down 2 meters a couple of times too. The river wasn’t anywhere near as deep as the 100m rating that Sofirn give.
When I was done I gave the light a rinse and dried it. As expected, there weren’t any signs of water ingress.
Interface and switch
The SD05 has a rotating “switch” instead of a button, presumably because it’s hard to make a physical button fully waterproof. I’ve never used a flashlight with a switch like this before. It’s incredibly intuitive and doesn’t need any explanation.
The switch feels very slightly loose and has 0.5mm play either way at each mode but this doesn’t seem to be a problem. The switch changes mode when it’s about 2/3 of the way towards the mode you’re changing to, whether that’s up or down. This is good, as it means there’s no half way point for it to flicker at.
The switch has very slight knurling and can be rotated with just a thumb, albeit slightly awkwardly. Using the switch with gloves on works fine. Not a problem using both thumb and index finger though. More knurling would mean use with just a thumb or finger would be easy.
The SD05 uses a magnet in the switch (a reed switch) to work out which mode it should be on. That means the light can be turned on with any magnet! This is unlikely to be an issue in most cases but is good to know.
Cell and charging
The SD05 came from Amazon with a cell, cell sleeve and a charger.
The cell is a Sofirn branded flat top 21700, that says it has a capacity of 4000mAh and current of 40A. The cell measures 21.5mm diameter by 70.8mm long. The 21700 cell protrudes about 5mm from the tail. My XTAR VC4 said it put 3829mAh into the cell from an almost full discharge, which is pretty close.
If you’re actually using the SD05 for diving then buying a 5000mAh 21700 cell would be worthwhile for 25% extra run time. Changing cells underwater is not recommended.
The sleeve is designed for 18650 cells but it’s a bit wide, with an innder diameter of 19.5mm. This didn’t seem to be a problem though and a flat top 18650 worked fine with it: sitting flush and making a good connection with the springs.
Almost any 21700 or 18650 should work with this light. The only cell I had that didn’t fit was a 77.6mm 21700 cell with integrated charging.
The single cell USB charger is basic but seems to do the job. It’s rated at 1A and a quick check showed it pulled 0.85A via from the included micro USB cable when the cell was getting full. The charger is spring loaded and should charge cells between 31mm and 72.5mm and mentions cells from 26650 to 10440. The charger is only 19g, so would make a good travel charger for lithium cells.
There’s only 3 modes but they’re nicely spaced. The modes seemed fine for use in water but 300lm is quite high for general use. When packing up after being out on the river, the 300lm low was a bit bright.
The SD05 uses a 3V LED and takes a 3.7V cell so it can use simple driver. There’s no voltage boost circuit here, which means the output reduces as the cell voltage drops. My light meter setup isn’t calibrated but does accurately show relative light output changes.
Normal run times
Left out on a hot day on high the light will step down from 3000 lumens after a minute. The supplied cell then lasted over 2 hours above 600lm before the low voltage protection kicked in. Holding the light and on a cooler day will probably let the light stay brighter for longer, meaning the cell won’t last as long. The SD05 got up to 55°C on high.
I tested the SD05 in water, to check the thermal regulation and also just because I could. The SD05 stayed above 2000lm for about 30 minutes, then started to drop off and only lasted 45 minutes on high. The output change as the voltage drop is more visible in the graphs. You can also see the low voltage protection kicking in, dropping the light to medium, then low and giving some warning flashes.
LED and beam, PWM
The SD05 has a 6000K XHP50.2 LED and orange peel reflector. The large head makes this slightly throwy (270m), with a smooth transition from spot to spill. 6000K is way too cool for my liking but neutral white 3V XHP50.2 LEDs seem hard to come by.
The driver uses PWM to dim the light in different modes. The PWM isn’t noticeable by eye but some beam shots showed the PWM much more than other lights I have.
Searching Amazon for diving lights gives all sorts of results, including some zoomable Shadowhawk clones that are definitely not waterproof. If you’re buying a light for diving then make sure you get one from a reputable company.
Here’s some alternatives I’ve found that are rated for 100m+
|Sofirn SD05||3000lm||270m||21700||magnetic rotating ring|
|Wurkkos DL40||5000lm||400m||2 x 26650||magnetic side switch|
|Acebeam W30||500lm||2408m (LEP)||21700||tail|
|Fenix SD11||1000lm||45m||18650||rotating ring|
|Acebeam D20||2700lm||296m||21700||side switch|
|Nitecore DL20||1000lm||223m||18650||2 side switches|
- Very waterproof
- Rotating switch is intuitive and well designed
- Beam profile works well underwater
- Stays on high as long as the cell can provide power
- Comes with cell and charger
- 300lm low isn’t very low
- 6000K LED is too cool for my liking
Subjective changes and improvements
Firstly, I’d have called this light the SD05B to differentiate it from the version with the step down.
The rotating switch could do with more knurling for grip. I don’t know how this would affect things for divers but it’d make using the light a bit easier for me.
The cool white XHP50.2 is the brightest 3V LED you can get but I’d be happy to sacrifice a few lumens for better light quality. A high CRI 4000K SST40 emitter would work well here. I’m not sure what effect this would have when diving though.
I’d like to see a slightly smaller EDC version of this light that only takes 18650 cells, has a smaller head and comes with a clip. To make it more useful for every day use it could do with 2 lower modes, around 1lm and 50lm.
The Sofirn SD05 was more fun than I expected – I’m now checking the IP rating of all my other lights to see if they can be used in water. The SD05’s quality is great and I have no doubt that this would be a solid light for actual diving. Sofirn listening to user feedback and updating the light is a great sign.
Thanks to Sofirn for providing the light for review.