Interested to see a beam profile comparison between the M21B, E, and F once you have them all.
Hi Stephen, your excellent review of the Acebeam with GT-FC40 https://www.stephenknightphotography.com/post/flashlight-review-acebeam-e70-al-cri95 was among my first introduction to the GT-FC40.
I will load pictures later but just some preliminary description now. As the top end of the flashlight becomes larger (and the reflector deeper and larger), a predictable pattern emerges: the hotspot becomes smaller but brighter, and the spill size stays about same but becomes dimmer. So from smallest to largest
M21B: Flood A+ Throw A-
M21F: Flood A Throw A
M21E: Flood A- Throw A+
In practical use where I start them at 100% and leave them running continuously during my 45 min walk: At first, M21E has brightest hot spot and furthest throw, M21F slightly better than M21B. Then as thermal regulation set in, the lights become dimmer, first M21B, then M21F, then M21E, which stays brightest the longest. After approx. 5 minutes, once thermal regulation has stabilized, the 3 lights look very close to each other such that I often can’t tell them apart.
Above description is for lights being on continuously, WITHOUT INTERRUPTION. If during the 45 minute walk I turn off the light and then later turn it on again, then M21E again would be the brightest, for the next few minutes.
I have the Olight M2R Pro Warrior (that has around 300-330 m throw) and the M21E based on brightness of hotspot at same exposure setting is pretty good, but not as bright. I would imagine that makes M21E’s throw 300 meter or below. Hope this helps - I’ll check pictures and see if above is still true.
(Post edited 4/29/2022 as my understanding of the 3 lights has changed after more usage time.)
Look like we have a convoy 
. Just a couple quick notes:
M21E is larger than I expected. Definitely a jacket light, pants ok but it has to be baggy lol. The screw on clip probably would work, just that the screws could be a touch longer because the wall of the M21E tail is thicker, for extra safety. Even if it does, I wouldn’t use it because for side switch I like to keep the clip at 9 o’clock so it stays out of the way of my right hand’s grip, and the holes are not at that position. The Convoy clip-on clip fits but I did bend the arms out a little bit so as it doesn’t scratch the finish too much.
M21F is very similar to M21B, just a little larger. M21F has slightly brighter hot spot, whereas M21B has a brighter near field flood. But the beam and brightness are close enough that the difference comes down to whether you like side or tail switch, and how important USB-C charging is to you. The lights seem to eat battery the way I use it (near Turbo level for 45 minutes) so USB-C charging is mandatory for me.
1 Thank
Thanks. I’m particularly interested in the angle of the spill beam as that is quite critical for night photography usage. My testing of the M21C with GT-FC40 was 60 degrees, and M3-C with XHP70.2 was 70 degrees. I generally prefer wider spill beams and I’m starting to gravitate towards lights with TIRs as they have a very wide (though sometimes dim) spill beam.
The lights in the middle seem to be labeled S21C, I’ve seen this in other pictures but I can’t seem to find this light, care to “shed some light” on the situation for me 
?
Haha your post startled me and made me rush to check the box 
, which thankfully does say S21D. Love the internet. Someone somewhere with sharp eyes/attention to details will detect what owner never saw.
I’ll ask Simon later but any Convoy expert around here? Is there such a thing as a S21C? I googled and found this: https://www.reddit.com/r/flashlight/comments/p57jej/photo_of_quad_optic_from_simon_for_upcoming_quad/ . So maybe a change of mind and old stock must be used?
PS Now going around checking all the other Convoy’s markings lol.
That’s the only reference I could find as well. As I wait for my S21D and M21F to arrive, I’ve been enjoying your excellent posts with the wall of truth. Atleast you know people are looking closely at your excellent and informative photos. I also noticed the markings in this photo of yours Imgur: The magic of the Internet. It seems both of your S21’s are labeled in this way. I only wish I had seen the metal button and picket clip when I placed my original order, I fear I will be awaiting another package soon.
I think Simon mentioned why the S21D has S21C printed on it somewhere in the Convoy thread.
Simon mentioned in his thread difference between S21C and S21D.
S21C - Triple 90deg TIR (ready to be on sales but Simon too busy to put up the listing)
S21D - Quad 60deg TIR
Interesting. The S21D is already very floody (and I’m a fan of flooders). I would think that the S21C having less output and even more flood would be a very very niche product.
Thanks guys for the detective work. Pheww nothing abnormal with my 2 lights then.
Is the picture below how you would measure this angle? If so then these are some rough numbers:
The Convoy GT-FC40 triplets: all 3 have similar angle around 70 degrees
Reylight Pineapple Copper with 219b 4500k: 85
The TIR lights do have large spill angle, but very dim spill as you’ve mentioned.
Olight TIR XHP35 HI 4900k: 100 (don’t bother checking CRI on this one )
Sofirn IF22a: 120
Are multi LED TIR not a consideration? If yes then Emisar D4V2 with 219b has angle of 125. Hope this helps.
Yes, that’s exactly the info I was looking for. Thank you.
I feel the same way. I like quad LED output and S21D is nicely floody already. In fact I am going to experiment with swapping S21D’s TIR Optic with the one from Sofirn IF25a, which is less floody but gives a brighter hotspot. Apparently they are interchangeable.
White wall shot of the triplets. The turbo run-down at home (no ventilation, sequential pictures for ~20 minutes) reflects fairly well real-life experience (turbo start during my 45 min walk, subjective eyesight eval).
M21E always has brightest hotspot and dimmest spill for the first 5 minutes of a run-down from Turbo. Once thermal regulation and step-downs have occurred, M21E remains slightly brighter than B and F. Note M21E is the largest & heaviest of the 3. More of a jacket-pocket (vs pants pocket) light. ~7.25 oz w/ battery
M21F has brighter hotspot than M21B when first turned on, but once thermal regulation kicks in, sometimes I can’t tell these 2 apart. I tend to think of this as the M21B’s twin, but with side switch and on board USB charging. ~6.7 oz w/ battery
M21B has dimmer hot spot but OTOH has nice spill that illuminates near field well. Addition of metal tail switch and clip makes this light so much more “loveable” lol. It’s the smallest and lightest of the 3 lights. ~6.1 oz w/ battery
Essentially… I love all 3. 
Pic of the smooth reflectors.
I would like to add that from beam shot above (post #55), it seems as the reflector gets larger (the M21E), the border of the hotspot becomes more delineated, more defined. But one, this could entirely be in my head , and two, it’s only seen with white wall hunting. IOW, IMHO for academic interest only and not noticeable or relevant in real life use in this case.
Thank you for all the updates. M21F is looking so damn good. Can’t wait for mine to arrive.
You’re welcome and thanks. Yes the M21F seems to be the sweet spot for EDC GT-FC40. I know the feeling - it’s like being a kid again waiting for Christmas day .
Automatic Temperature Control (ATC): All 3 lights have ATC - and brightness seems well affected by it. Within a few minutes of Turbo start, there’s that big step-down seen in all lights that I have (not just Convoy). In addition during my walk I could feel the different lights become colder or warmer at different times. I do not have any instrument to measure precisely the brightness change, but could obtain rough estimates by taking sequential pictures, at 1, 2, 5, 10 min, etc. after a Turbo start.
Note that all tests inside are excellent to see precisely the light beam and brightness level, but they may not reflect accurately actual use outdoor wrt temperature regulation. For example the lights get extremely hot during indoor test, and never so in actual use during my walk. Outdoor ventilation makes a big difference.
When I asked Simon about the difference between all the Mxx GT-FC40 flashlight models, he mentioned the M21D is at an advantage because of its “thermal capacity”. I am guessing that as the light gets larger, it’s not just a deeper/larger reflector that is different, but also the ability to dissipate heat from the inherently larger space of the head. In turn this should improve the ability to maintain brightness. Following the trend of B, F, and E, I would expect M21D to have the brightest hotspot, dimmest spill, and best ability to maintain brightness?
I have 3 Olight M2R Pro Warrior w/ XHP35 HI (flat) LED and they each have distinctly different brightness (the Orange one is brightest, Patriot dimmest) and tint (Orange least green, Patriot green hell) 
. For the cost, I was hoping for better quality control.
I was relieved when I saw the beam shots of the GT-FC40 triplets having similar color/tint. Clearly coming from the same bin and thank goodness that my comparison pictures for M21B still applicable to E and F.
The M21C/D and M3-C have more thermal mass. My testing has shown sustained brightness at approx 1000 lumens with GT-FC40 5000k in M21C and approx 1400 lumens with XHP70.2 5000k in M3-C.
Thanks. Thermal mass meaning aluminum frame of the flashlight acting as heat sink? I was just thinking about the larger air space above the LED but this makes sense to be the more important reason.