I’m not really clear on the measuring technique and can’t help wondering if it’s creating more confusion than help? I say this because there’s no mention of any form of collimation to the light output and if that’s true you’re attempting to measure candela without focus. Seems it would be quite a skewed reading when compared to actual in-light performance. Measuring candela is largely a function of the reflector/lens/optic, as can be seen in the 703Kcd measurement of this same emitter in the large reflector of the TN42. Same emitter, pushed harder, in a MaxToch Shooter 2X makes some 332Kcd. So the candela (or lux) measurement is not a function of current/Vf, but rather a proper collimation of the output.
The formula applied confuses me. I truly don’t see how a meter reading taken at ~15 inches distance can be applied to surface illuminance. How did the figure of 38cm come into play? A mule (bare emitter with no reflector or optic) spreads light at 125 degrees as a component of the dome, wider if an HI variant, so there will be a great deal of the light dispersed beyond the meter at that range. Cree’s graphs don’t show a distance of apex of the transmission from the applied dome, nor from the dome-less HI (not that I have seen). Sounds pretty non-standard and as such the result, while looking good on paper, might be misleading. (at least, it is to me personally)
When I or TomE or Richard or a number of other forum members quote lumens from a light box it’s an out-the-front transmission of light. Mixing in candela on such graphs doesn’t really give a true picture to what the emitter is producing, as it’s not the normal standard we compare to.
Of course, there’s a lot I fail to understand.
I’m not saying any of this to be facetious or debunking, merely trying to understand such that I may use gained knowledge in the application of these emitters to my own lights. (as if I’d remember even if I understood)
I should also make note that I have learned to address a reply to the masses even when talking to an individual, so that others can see my thought process and if applicable, correct me where I’m wrong. I surely don’t intend to create my own confusion in others, but am relying on others to guide me into the light, as it were.
(I may have talked myself into a measure of understanding by constantly double checking what was said and charted in making my response. The question was one of throw, the large multi die emitter throws similarly to a de-domed XM-L2 while making considerably more lumens available, as such, the same intenstity at range is available in a broader hot spot. This was my finding when I converted the Shooter 2X, nearly twice the lumens, at 4 times the voltage, for similar Kcd)
Sorry for being so long winded in what seems to be a conversation with myself. :person_facepalming: