Thanks for this head to head comparison. I’ve been looking for something as powerful as my Q8 but in a smaller size. I thought I’d need a larger light with perhaps a XHP70.2 emitter but it seems that the D4S (even with the tradeoffs) is a contender.
Thanks for the comparison, I was also looking for something like the Q8 but smaller. 
Can’t wait to get mine!
Will add my own video beamshot test comparisons (each Youtube video is around 20 seconds long) for each of these flashlights:
(direct ground distance of flashlight to the building on the opposite side is around 125 meters or 400 feet, as checked with Google Maps; but since it's more of a diagonal up, I'd expect around 150 meters diagonal distance)
(tests done with fully-charged batteries: around 4.15+ v ; the Sofirn & BLF Q8 use 4x VTC6 [not "new" ones but have been using them for testing for the bigger part of this year]; while the D4S use cyan INR26650-50A [supposed to be similar to Lii-50A])
(recorded the D4S twice)
(indicated "lumens" are not my measured lumens but the "manufacturer rated lumens")
1) Emisar D4S (quad Nichia 219C 5000K CRI90, "3000 lumens")
2) Emisar D4S (quad XPL-Hi, V2-3A, "4300 lumens")
3) BLF Q8 (quad XPL-HD V6 3D, NW, stock, except updated to Anduril, "5000 lumens")
4) Sofirn (quad XPL-Hi, CW, stock, except updated to Anduril, "5000 lumens")
5) Emisar D1 (XPL-Hi, V2-3A, "1250 lumens")
notes: Sofirn Q8 is a lot more throwy
Awesome videos d_t_a Thank you for sharing…!!!
I agree………. :+1: I also really enjoyed your post Frumious…… almost felt like I was there in Alaska at the base of the cliff with the moose and owls…. Coooool! Still in the low 80s here during the day
I havent ordered my D4S yet but I do have a D1S that is lonely for a floodier brother for EDC.
BTW, Welcome to BLF!
Thanks for these videos d_t_a.
My Q8 is the stock BLF - the same as video #3. My D4S has the same emitters as both #2 videos.
I notice in the first of the two #2s there appears a substantial and quick drop of brightness. That drop is not so noticeable in the second #2 video.
Perhaps because it is cold up here, temperature activated step-down does not happen as quickly. Also, I read instructions in one of TK’s posts for how to raise the activation point of the temperature step-down from its low factory default. This would also extend the time the D4S stays at max lumens. I had planned on doing this but after the cold trial did not see the need. I now think I will do it anyway.
Thanks again.
Coscar -
Thanks for your welcome. There is real nice camaraderie here on BLF. Everyone helps each other.
Yes, Alaska in winter, with its lonnnnng dark nights, is a great place for flashlights!
I went out again tonight and witnessed an extra bonus: pale green waves of Northern Lights!
Yes, Frumious, nice little essay there on how these compare. I’m not surprised you found them so close in overall performance, nor am I the least bit surprised that it’s the run time and heat that creates the division between the two.
I was surprised to see your report, a friend of mine just got back from Alaska and he really enjoyed his week long excursion. Lights, especially really good lights, are notably essential for that climate. Glad you found the right ones and that you’re enjoying them. Is it safe to leave the Li-ion’s in the glove box? I mean, overnight temps can be brutal… not something I’ve ever had to worry about so I’d likely forget and maybe kill a good light or at least a good set of cells.
Welcome aboard! (hide your wallet!)
I don’t recall seeing it mentioned elsewhere: how is low on the aux LEDs implemented? 2nd digital out pin and resistor?
Still loving my green/cyan XP-L 4k (can never remember the color code), which spends most of its time in aux hi as an expensive nightlight. The FET gets very little use, as the 7135 mode is so much brighter than the D4, that it’s usually enough. It is the best tint of any light except maybe the SC600m3hi. I guess the HI is a nicer beam than the 2, and four of them evens out the corona even further. Lanyard spike isn’t annoying me as much. Sorta wishing I got the magnet tailcap.
@DB Custom, as long as you don’t charge them in the cold, no problem at all. Also, get him some high drain cells, or even high drain 30A ones.
The lower the internal resistance, the less cold will affect performance.
TKDR: DON’T CHARGE CELLS IN THE COLD.
That is important advice for anything that uses LiIon batteries. Laptop, phone, whatever. It may sense the temperature and disable or limit charging, or it may not. I really don’t need an unhappy 26650 cell in the house. Also why I wish for a 21700 Emisar, since IDK if we’ll ever see one of the big mfg making a 26650. Wish we would, it’d probably be 6Ah.
Thanks for the welcome DB Custom!
Good question about Li-ions in a cold glove box. I had to think about that for a moment. No, that is not a problem. In fact, one of the hot selling items up here is a Li-ion car jump-starting battery that you leave in your car all winter. It is amazing how small these are - about the size of a small paperback book. I charge it in the fall and it holds its charge through the winter.
Thanks BlueSwordM. I did not know the connection between internal resistance and the effects of cold on battery performance. Fortunately, most of my batteries are high drain. I’ll keep the others out of the cold.
Hey, look another Alaskan!
I use my D4S a ton more than my Q8 as the Q8’s are sitting inside each of the doors (front and back) right now. I don’t like how much pocket space they use in my jacket. For smaller pocket carry it is still the D4 because, well crazy lights are fun.
The Q8 badly needs a wrist strap. Walking out and getting into my truck with my hands full (pool cue case, drinking cup, truck keys, maybe a snack, and the Q8), I’m really scared I’m going to drop the Q8 on the pavement.
Hi Strayz. Small world isn’t it. I wouldn’t be surprised if there are more Alaskans on this site. Can’t do without good flashlights up here during the dark half of the year. And this site is terrific for learning about portable lights: headlamps, fat bike lights, rifle lights, camping lanterns, search lights….you name it, we need good lighting gear. I have a friend who goes ocean diving in the dark winter - he needs lights.
I’m a fan of the Q8, but size matters. The D4S is a handier size. And, yes, its a crazy, fun, bright light.
Is there a chance that Emisar will make a short tube for the D4S? I know that with a 26350 it can’t be that bright but in some situations size counts more than output and you will not use it on full turbo many times. However I like the “fatty” look similar to the Fitorch P25. And of course I have 26350 batteries and not many lights that need them.
Thanks for the feedback.
The D4S (XPL-Hi) was just a few days old when I did that video, I had not calibrated the thermal configuration yet. But we’re in a hot tropical climate (it’s stll arond 30 degree Celsius ambient temperature here right now, in the evening). While reviewing the D4S video, I notice the brightness stepped down quite quickly (I hadn’t noticed it when I was capturing the video with my digicam), which is also why I did the video twice, to show the brightness when in Turbo.
As far as I know, using the internal pull-up resistor of the MCU. Which is why it’s a fixed level which can’t be adjusted higher. You could change high level fairly easily by changing the resistor on the aux board.
Not just as far as you know. That’s the way it is implemented.
High = Pin set to output and pulled high
Low = Pin set to input and ~30…60k PullUp enabled.