[Technical discussions] Sofirn SP35 - SST40, 21700 size, buck driver

I ordered the SP35 kit from Amazon on 06JAN21 and it arrived on 14JAN21. Kit was complete, with 21700 4000mAh battery, clip, lanyard, and O-rings (o-rings are in the small ziplock bag with the lanyard, look closely). I’m impressed with the output of this Sofirn, it lit up my 2-acre pasture (0.8 hectare for the rest of the world) very well. Eco mode is sufficient for me to walk inside my house with all other lights off. UI works as per owners manual, I like the double-click to go from Off to Turbo mode.

I received my SP35 about a week ago and have been playing around with it. Overall, I really like it! My review is up here

Pretty much everything I’m seeing is inline with what Funtastic has mentioned so far. The only exception is either I have an updated reflector or I’m less sensitive to the beam, one of the two.

Got mine today, but I am very disappointed!
With a full Molicel P42A mine barely reaches 5.4 A at turnon (tested with several cells and even VTC6, despite them not fitting…).
And it has only 21 kcd which is way below the 27.5 kcd that were promised…
That seems way off - is my flashlight defective or did you guys get similar results?

Hmm, I measured 24,250 cd which is just a little below spec. With regards to the amp draw, remember this is a buck driver, not a FET. Instead of burning of excess voltage, it trades volts:amps. You may be seeing 5.4A at the tail, but it’s likely still delivering 6 amps to the LED because of the buck.

For the modding crowd out there, I was able to easily break the glue loose. I’ve got some pics and dimensions here: [Review] Sofirn SP35 - SST40 21700 Buck Driver - #21 by gchart

27kcd is just simply a very optimistic rating for a light with a reflector that small and emitter that large.

How much differences in throw would this have over sc31pro?

Probably very little, the reflectors can’t be very different in dimensions, the emitter is the exact same and is driven to basically the same level (maybe a bit less even).

Is this the same light?

https://sofirnlight.com/sofirn-sp35-max-2000-lumen-no-stepdown-version-with-buck-driver-works-with-your-typec-charger-p0165.html

The one and the same!

It looks like they’ll also be stocking it at Amazon eventually (non-aff link). I bought mine through Amazon; it shipped from China and arrived relatively quickly. Good pricing on the one directly from Sofirn’s website. When I buy stuff there, it usually arrives within a couple weeks - pretty fast for China shipping.

Dumb question, I am trying to learn all the terminology, what is the advantage of the buck driver (vs. which driver?)

More controlled/consistent output and, if implemented correctly, more efficient than some other styles. There’s an explanation thread here

Thanks, I will read more about it.

Does your SP35 beam look more like the one on the left or the right?

Left side beamshot is an “early batch” SP35, probably belonging to the 1st 100pcs.
Right side beamshot is a bit newer SP35.
(both shots taken at same camera setting: 1/10th second shutter speed, daylight white balance, ISO-800)

I’m guessing that, as a dealer early in the queue, and provided with a preview unit, Funtastic received one with the original reflector with the larger but inconsistent spill (“left”).

The beamshots in gchart’s review resemble the one of the right with the newer reflector, with a more clearly defined hot spot, less spill, and better uniformity.

It would be nice if Sofirn were to provide some official clarity on which version one would ship if ordering now. The sales figures on their stores (~150+ sold) would suggest that the early batch has been exhausted, but that would only apply if they don’t commingle the two versions in stock, with each shipment a random draw, and a lottery for the customer.

Something that hasn’t been mentioned here, but on TLF, are plans for a 35T, with a tail switch.

Based on the sp35?

No idea if they mixed them, good question.

Here they mention the SP35T so knew something was on its way

Yeah, definitely was the one on the left. Quite a shame as it makes the beamshots in my video review useless now.

Yes, mine looks like left too.

A little bummer really, if anybody knows if we can get replacement reflectors that would be neat :smiley:

What’s wrong with the one on the left? Just looks floodier to me.

With the old reflector the transition from spot to spill is not that smooth and looks rather unpleasant. Also you get a very noticeable green ring around the spot, which you can notice in the comparison shots above.

Here is mine at closer range:

https://i.imgur.com/q8XalbG.jpg