Sofirn SD03 diving light, first thoughts

I have not seen anything on this 100 meter diving light yet on BLF or the internet, so I thought it might deserve a thread. I bought this in a recent sale for under 20 dollar and may as well show it to you :slight_smile:

I bought the SD03 because of the distinct styling but it was more hefty than I thought, considerably larger than a Thorfire VG10 which has the same reflector size and is already not the smallest in its class. Weight w/o battery 183 gram, (130 gram for the Thorfire).

It houses a cool white XM-L2 led which on the brightest setting puts out 800 lumens (on a 3100mAh protected Keeppower that was not completely topped up), medium is 350 lumen, low is 80 lumen.

UI is simple and easy to use, a magnetic ring with a ball bearing that locks in discrete positions selects off, low, med, high, off, repeat. The ring can fully rotate so from off you can select low to the left and high to the right. The ring rotates fairly easy and I could operate it well with thick gloves on, but there is no lock-out possible other than removing the battery.

The SD03 can open in 4 positions along the flashlight (picture shows 3 of them), I would think that could be less, any opening is an extra option for water to get in. At least all positions are protected well, with generous threading and double o-rings that are well-lubed (no lube came with the light btw, for re-lubing I used some that came with an Archon dive light).

The head can open just above the magnetic ring and also at the bezel. The glass window is huge and is firmly pressed by the bezel onto the lubed o-ring. The led is on a 20mm aluminium non-DTP star, which is fine at this output. You can see in the pic that I already swapped it for a sliced LH351D (the famous 5000K 90CRI dogfart led) on a DTP copper board, the reflector was reamed to 9 mm to fit a different centering piece. To my dismay I dropped the freshly lubed o-ring into the reflector :person_facepalming: so that had to be cleaned completely (water, soap, soft tissue etc.), it looks good again but will never be as pristine as before.

The new led is a bit throwier than the stock XM-L2 and the spill is a bit ringy, but I doubt it will really annoy anyone in use. I measure 700 lumen on highest setting (not much worse than stock :+1: ), CCT 4500-4600K, depending on brightness, and not much different in the spill. CRI is around 91 with R9=50, tint is on top of the BBL or slightly below.

I should remove and show you the driver, but that looks quite a challenge (it is behind a plastic disc that looks like it will break upon removal) so I will give it first to a collegue of mine who will check its use under water. She dives down to 25 meter so the light will not be tested to its max, but I hope she can give an impression of usefulness.

Preliminary conclusion: The SD03 seems good quality, I could not find obvious faults. The magnetic ring is an attractive and convenient feature. As a non-diver I can not help thinking that the SD03 could be built less plump, with preservation of function and performance, but the size and heft may as well be a quality under water.

So, to be continued…

Gotta say, that’s one nice chunk o’ glass!

Looks like an all-around nice light, but yeah, I’ve got concerns about how many threaded junctions it has.

My “ideal” diving light (not that I go diving…) would be to have the front glass press-fit from behind into an S2+ type bezel/head, held in place by the reflector and LED/driver pill, then screwed onto a 1-piece battery tube like on an AAA twisty.

This way, only 1 threaded junction (all O-ringed out the bazoo), and of course the glass-to-bezel junction.

Still, that’s a nice looking light!

Dunno why the almost universal fascination with CW for use underwater, though, when most of it would just backscatter right into your face, vs a nice WW that would penetrate murky water a lot better.

Don’t know either, cool white sounds bad under water. At least on land the tint has improved immensely with the new led.

I measured some currents, I suspect that the currents on the stock XM-L2 are a bit lower than with the LH351D
*ring in off position, 44 micro-amps (8 years to drain the battery :+1: )
*low, 160 mA
*med, 1.3 A
*high, 3.3 A

@ Lightbringer:
I would have thought the same, however I recently stumbled upon this video from Reddit. This link to my Google Photos
Unfortunately can’t upload to Imgur as more than 30 sec.

Seems the yellows then the reds are absorbed. Cool whites would have bluer predisposition and better rendering.

Nice video! But it is food for thought though. You could argue that to penetrate water best and see far away, you need cool light, or you could argue in order to see colour contrast best you best start with lots of red, so you need warm light.

Looks like ugly green tints would go the farthest… :confounded:

I don’t know of the validity of the video, but it was threaded that the pink may be a ‘neon’ colored marker cap (which btw are Crayola).

Have you been able to access the driver? I wonder how versatile the control ring is. I can’t imagine smooth ramping would be possible, maybe step ramping.

I have not looked at the driver yet, the light (with led-swap to Samsung LH351D 4000K 90CRI) is currently lended out to a colleague who will take it out diving one of these days and will give me his thoughts (nothing deep but it will give an impression).

Smooth ramping will require different components on the driver and may be more difficult/expensive to implement.

I was looking at the SD02, thanks to a heads up from LightBringer. But then I spotted the SD03 and came over here for the review. Spec wise the two flashlights don’t seem too far off in terms of temperature and throw. The SD03 ring control seems to be a more sensible design than the switch on the SD02, because you don’t have to rotate the body to find the switch.

Driver accessible? Any news on this? I’m very curious.

I gave my SD03 to a collegue who is a diver to check it out underwater and he was happy with it and he asked to keep it. So I do not have it anymore to check the driver :frowning:

I guess I’ll just have to buy one, then.
For $15.93, worth satisfying my curiosity.

P.S. — on reading the product description, does anyone know what “military level 3 stereoplasm anodic oxidation” refers to?

The extra double space in that string is correctly quoted; might be a missing comma or semicolon between two different items, or might be the whole string refers to a single …. something.

There’s a separate line describing the black coating on the aluminum:
“Premium Military SpcⅢhard-anodized anti-abrasive finish and better heat exchange”

Meanwhile, what really captivates me is the UI:

PS: has anyone plans to review the SD05
It’s a 21700 light.

I avoid Sofirn’s dive lights as they have the annoying 3 minute step down to a ridiculously low Med setting. There’s not much use of it diving. You need a steady high output to illuminate your surroundings underwater

I just got an SD03 in today’s mail.

Bought it because (a) affordable, and (b) my first light with a magnetic control ring

Decent yellow spot, some flood around that, and a blue ring at the extreme outside edge of the illuminated area.

Looking from behind the light, turning the ring counterclockwise from Off it’s Low, Med, High, and off again.
Clockwise from off is High, Med, Low and back to Off.

Feels solid, like a potato masher grenade.

I don’t get a stepdown at three minutes (I was patient up to about five minute mark).
Maybe it’s a temperature rather than a time based change? it could just be I’m in a rather cold house ….

@ hank:

Originally had my sight on the SD03 as it didn’t seem to have the timed step-down. Sofirn informed me of unavailability and offered the SD05 with discount.
The SD05 has timed throttling - quite stupid given it’s a watercooled light and in ambient air has thermal control.

Here are my results (using a phone’s light meter and my standard* for conversion);

First 3 minutes 316 lux -> 1150 lumens (steady output)-
at 3 1/2 mark 286 lux -> 1050 lm-
at 4 minutes 246 lux -> 900 lm-

Edited (⌃had not fully charged the battery⌃):

at start - 772 lux -> 2830 lumens
at 1 min - 765 lux -> 2800 lm
at 2 min - 684 lux -> 2500 lm
at 3 min - 542 lux -> 2000 lm
at 4 min - 318 lux -> 1150 lm
at 5 min - 264 lux -> 950 lm

Temps in the 40º to 44ºC. I was curious so I fetched it from the car, which is –10ºC (~25ºF). I added an open celled neoprene glove around the shank, too cold to handle bare hand.

  • Don’t have a Mauka calibrated light but a RayoVac alkaline stated 382 Lumen unit. Been my standard for some time as gives ballpark values.

But the ring switch is very practical - no fumbling about to turn on.

Since then, I purchased a Wurkkos WK20S (identical construction to the SD02) albeit an XHP35 HD emitter (the Sofirn’s using XPL - both at 5500ºK). The switch is soft and very enjoyable. The throw with spill is quite good.

Never took them apart, notoriously glued - using as is out of the box.


Eh? It’s still for sale: