Looking on Digikey as a source for LH351Ds
I get 2700K CRI90 310 and 330LM binnings
for 5000K CRI90 390-410 binnings
so 4000lm for 5K
and 3200lm for 2.7K
Looking on Digikey as a source for LH351Ds
I get 2700K CRI90 310 and 330LM binnings
for 5000K CRI90 390-410 binnings
so 4000lm for 5K
and 3200lm for 2.7K
also why not simply compensate the lumens in the firmware to have on any color 3200lm just do the 5000K only on 80% max current?
Just to get it right: Do you mean a balanced output, i.e. the flashlight will always have let's say 3200 lumens output regardless of the tint's CCT?
yes
you could then also make in the firmware an option to blast out Turbo with all LEDs and max current at about 4000K
Okay, I got you. :-) Good idea. Sofirn did not balance the output on the IF25 (yet). Effectively, not only in perception but also in actual numbers it is brighter on coldwhite than on warmwhite. They also did not implement the fancy feature of using all 4 LEDs on Turbo (yet). However, your ideas definitely belong to the wish list of the UI a perfect flashlight should have.
A revised draft concept...
Ehm...IN!!!!
Hmmm… Tint ramp is not a huge thing for me, but then again, I’ve not used a light with tint ramp.
I like the idea of a separate red in the center. Sometimes you need a more gentle and nighttime friendly light. Then again, dropping what I assume is an Osram thrower in the middle defintely adds flexibility. The unicorn flood/throw combination light.
Size — I’m torn on this one. As a pocket light, even the 21700 might be a bit big for my tastes, let alone a 7 LED head. As a holster / shelf light, I like the feel of a 26650 tube, which might be a better size match for a 7 LED head. (reference - I have most recently used an FW3 and EDC18 as my pocket lights, and they are IMHO, on the edge of being to big for pocket EDC)
I was wondering about this the other day, and since I saw this, I figured I would ask. Is there any potential advantage to using the red LED in the tint mix? Most phosphor-based white LEDs tend to lack red, right?
ETA: Or is that already the plan?
I don't know if using the red emitter in combination with the surrounding white emitters would result in a nice beam pattern. I would rather expect it to look weird. So, the red / deep red emitter is more likely to work separately as auxiliary illumination in lowlight scenarios (e.g. camping, preserving one's night vision, no attraction of insects, nightstand light, ...). Using the Osram White Flat 1mm² instead could be interesting to put out more throw as a centered hotspot in combination to the floody LH351D beam.
This looks like a great concept, I like it. I’d be more of a 4-LED 18650 kind of guy for EDC, but this seems like a good camping trip flashlight that can also serve as a lantern. 5700K while hiking for visibility, mixed tint while cooking food and 2700K when relaxing and reading a book. Just throw on a silicone diffuser and you’ve got yourself a lantern. Maybe a folding hook in the rear to be able to hang it in the tent or from a tree, with a magnet in the cap to keep the hook folded and still being able to stick it to metal surfaces.
I’ve been waiting for my IF25 from Aliexpress since 11/11, but I’m not sure when it will arrive, or how good it will be with the 70CRI 6500K SST-20s. Also waiting for my BLF LT1, but a flashlight like this could replace them both for my use.
So, I revised my original idea and tried to set up something new, something easy to operate...
(please excuse this rather simple design draft....just for illustration...)
Specs:
Output: approx. 4.200lm white light with a mixed tint of 4.500K 90CRI and approx. 400lm deep red light (660nm), emitters to be driven efficiently - not pushed to their limits
Host: Proprietary, mid section maybe based upon Sofirn SD05 or IF25A, front section (head) new design with wider head diameter (40-42mm), tailcap + switch Sofirn SP70
Optic: LEDiL TAMPA NIS83-MX-7-W (wide beam, 35°, 38mm diameter)
Bezel: Stainless steel bezel
Emitter: 3x LH351D 4.000K 90CRI, 3x LH351D 5.000K 90CRI, 1x SST20-DR (660nm)
Driver: fully regulated boost driver (wishful thinking)
Power: 1x 21700 flat top
UI: magnetic rotation ring controls stepless brightness only (moonlight to turbo), tail switch controls modes (tap for mode selection between white and red light, fully press for ON/OFF)
I like this new idea 
Seems a very well thought flashlight!
One question, though: the tailswitch would be a e-switch or a foward clicky switch?
I like it.
I like this, too. Nice design.
How about 9 LEDs? or have both a 7 and 9 LED variant.
Edit: 9 months ago I said 4 LEDs 
I like the thrower version.
Am I a minority here or what, but why would someone want a flashlight that is anything <5,000K. I know that a lower number K LED light will yield a higher CRI, but this is a flashlight after all and not photography lighting. If someone wants higher CRI then he/she might as well go back to using incandescent light bulbs. Newbie here, so please educate me.
I have my fire suit on, so go ahead: fire away.
Hi tammap!
It all comes to a matter of personal preference. For example, I use my warm white FW3A a lot at night when my eyes are alredy used to dim and warm light, and in that conditions warm white seems just white, and my neutral lights seem cool. It is just easier on my eyes, more comfortable.
Then again, I have a 2700K led lamp on my desk to study, just because I like it, and late at night cool lights don’t seem right to me. In addition, I think it is better if you have to sleep inmediately after stopping studying. In this conditions, the transition from warm lamp to warm flashlight is “seamless”.
Of course, If you like cooler neutral / cool whites then you don’t have to be educated, it is fine. I would try an inexpensive warm flashlight if I were you and had the chance, just to try it if you haven’t, but if you know it isn’t your cup of tea then again it is just fine, personal preference.
An e-switch would probably make this much more complicated to design (double-tube), so I would suggest using a mechanical (reverse/forward) clicky switch.
Not sure if there's a 9 emitter optic with less than 40mm. IMHO, going beyond 40mm will make this light too big and ugly using only one battery. Moreover, there's little benefit to expect with 2 more LEDs, making this light only "more floody" than it is already. :-)
I would also like the center LED to be something for long distance illumination. But I did not find any optic that has multiple beam angles, so something like Osram's White Flat will not work well here. In such a case, a classic multi-emitter reflector might be the better choice but then again the head diameter will become huge. UV LEDs will not work either as their wavelengths will be filtered out by most plastic lenses.
Concerning the tint: Many people here seem to favor a tint between 4.000K and 5.000K. The downside of HighCRI emitters is their worse efficiency but this could be solved by driving an array of six LEDs at reasonable currents, yielding in a beam that is both bright and pleasing for optimum color rendition.
Update:
I revised the OP with the latest draft and some spreadsheet about the specs. An integrated USB-C port might be a nice add-on, too?
Maybe add some knurling to the body? Preferably not the pineapple style though 
That’s what I was thinking!
As far as changing the type of light/led (white or red) that needs to be well thought so that we can always know what we will have when turning on the flashlight.
That is why I asked about the FC switch.
I am not sure if it would work but the way I imagined would be: from OFF, half press (or double half press) the tailswitch to change between red/white, and then a full click to really turn the flashlight ON with the already selected led ! The brightness level could also be defined more accurately before turning the flashlight ON.
That way there would be - in my perspective - less accidental changes between red/white, and a better definition of the level you want when turning the light ON.
Just a thought of course!