For my first review of a flashlight, I'd like to write a bit about the SD05 diving light by Sofirn. I will be reviewing the 6000K version with 4000mah battery/charger combo. This light may be purchased through Amazon through the link below (shipped from the U.S.). Use the coupon code for a 29% discount on the listed price.
https://www.amazon.com/dp/B07SJ5J6YQ?ref=myi_title_dp
29% discount: ZSBG3RMQ
This light represents a couple of other firsts for me. It is my first 21700 light and it is my first rotary light. I will be reviewing it less from a technical standpoint and more from real-world observations and opinion.
Everything came well packaged and protected in a nice, small, plain box. The flashlight was wrapped in bubble wrap to keep it safe from bangs and scratches from the other items in the box. There was also a small piece of foam for padding. Included was a simple but effective charger, a USB cable, a spacer to use 18650 batteries, a small bag with two extra o-rings and a lanyard, and an instruction manual (in English, German, and Russian).
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The light itself is actually smaller than I thought it would be. The body has only a slightly larger diameter than an 18650 light. Its head grows to the size of a 26650 light to hold that big orange peel reflector and to help with cooling. Those cooling fins have a maximum depth of 3mm. Comparing it to Sofirn's own SP32A V2 and SP33 V2, it is the shortest of the three. Like the SP33, it's not meant to be clipped inside a jeans pocket, but then, it's not meant to be an EDC light. Carried in a jacket or cargo pants pocket is no problem. I was surprised by the lack of any knurling anywhere on the light. It can be a bit slippery, but fortunately the rotary ring has indents that allow decent grip with index finger and thumb. I still think a bit of roughness to the finish would help.
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Inside the flashlight itself was a Sofirn 4000mah 21700 battery. It states "40A" on it. That's a rather high drain rate claim that I cannot test, but even if it is overstated by a factor of two, that's still more than this light can draw. In fact, if you wanted more capacity, I'm sure a 5000mah 10A battery would not affect output.
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The lanyard in my set is ridiculously long. The tailcap has a large enough hold to attach the mini clip from the lanyard instead of the usual smaller cord. The little locking bead is needed if using this light in hand underwater, as an open lanyard tends to get pulled loose by the motion of the water. The length is good in case you need to throw your light at an attacking fish while still keeping the fish at a distance.
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The tube has different sized threads on each side, both well lubed, and both with two o-rings. There are springs on both sides, which allow the use of 18650 and 21700 batteries. In fact, the included 21700 feels a bit long for the light, but does fit comfortably. Even an unprotected flat-top 18650 holds with no problem. As usual for Sofirn, the head seems all glued up.
Using the rotary ring is a delight. Despite, as mentioned earlier, the lack of knurling, the switch has just the right amount of resistance to prevent worry about unwanted mode changes without being difficult to manipulate. There are detents for each level that hold the ring in place. The light level changes about midway between each detent. Even underwater it was relatively easy to operate. It would be improved by some form of grippiness though. The only other improvement would be an infinite adjustable light level, though that would probably add a significant amount to the cost.
Being the 6000K version, I was initially worried about the tint of the light. To my delight, it is actually quite nice. It's not high CRI, and on low there is a bit of a green corona around the spot, but it avoids the sickly tint that makes everything look like a mysterious, foggy night. On medium and high, it simply looks white. The modes are well spaced, though again as this is not an EDC light, there are no "low" modes. Low is 300 lumens, mid is 900, and high is 2550, as claimed by Sofirn. I have no reason to doubt these numbers. This means it's not a great sneak-around-the-house-at-night light, but it can be used quite well to light a room if the power is out.
Using a Cree XHP50.2, I was concerned about the light having a donut hole. Yet again, I was pleased that this is not the case. The spot is nice and even with a slightly dimmer (though slightly green) corona, fading out to a slightly blue outer ring. It is much nicer than the beam produced in the SP33, as well as having a better tint.
The big thing here, if using this light in the water, is the fact that there is no longer a step-down on high mode. There are other reviews who have put this light through more rigorous depth testing and the light performed admirably. I was able to run it only to a depth of 4 meters in a pool whose water temperature was 29 degrees C. There was no problem with ingress of water. There was also no problem running the light on high. After ten minutes, the head of the light felt as cool as when I first turned it on. This means that is can be run on high indefinitely while diving. The claimed runtime is one hour thirty-eight minutes on high (probably including output at lower levels as the battery drains), so that would provide maximum brightness for a respectable dive-time.
Due to the size of the head and the cooling fins, mid level is sustainable even when not in water. So if this light was to be used for a night hike, and the 300 lumen level is not enough, 900 lumens can be had as long as the battery holds out. The beam is a good mix between flood and throw When used on high, it makes sense why Sofirn initially used a stepdown timer on the older version. It takes a few minutes, but the light does heat up. I don't know if the old version also had temperature control, but this version does, and to my surprise it works quite well. It takes between three to five minutes for the light to start ramping down, keeping the temperature below 55 degrees C and around the mid setting. Resetting the light back to high will return the brightness to at least close to its full power, but ramps down quickly again if the light is still hot. It would probably take several attempts at doing this to actually get the outer temperature to surpass 55 degrees.
Overall, I am quite pleased by this light. It certainly succeeds in its intended uses and even excels in some areas outside of its wheelhouse. Its ease of use means you can hand it to anybody and that person can figure out how to use it. If going diving or hiking (or taking out the garbage and not wanting to be bitten by raccoons), this would be a light well worth bringing along.
