Ok, well I hope he does a bit more testing to figure out exactly how intense the flat black is, because I would really like to have an alternative to the XP-G2.
This is the graph I’m looking at, and I’m not sure if the S4 2B in this graph was dedomed or not…
If it was not, then the lumens coming from my XP-G2 are probably significantly less than 1400 since dedoming loses some lumens.
Since the flat black doesn’t need to be dedomed, it would still have 800lm/mm^2 which would be a lot more than the 500-600lm/mm^2 of the XP-G2 (because ~1000-1200lm / 1.45^2)
djozz does not measure luminance of LEDs, he measures lumens. Two totally different things. For throw you need to know the luminance [cd/mm^2]. Lumens per square mm of DIE-area should be a good estimate though, but only if the actually value (also the size) measured is actually precise and representative of all the LEDs of this kind. For Osram LEDs this isn’t the case, because you can’t buy the Black Flat 2 in a single BIN. Osram only sells you a range of Bins. In the German TLF forum multiple people have found out that there is a rather large variance between these LEDs. If you want a “good” Black Flat that will actually produce the super high luminance values, you either need to be lucky or buy multiple LEDs and test them individually under the same conditions. Testing means that you test with a lux-meter if it gets brighter until 4A or even 4.5A. If it doesn’t, you got a “dud”.
Here is a thread in the German TLF forum, where somebody tried to precisely measure the luminance of a Black Flat. His LED got brighter until 4.5A where he stopped measuring. He didn’t actually calculate the luminance from his measured values, but sma and I did that for him. His LED managed 250cd/mm^2. That is around 10-25% better compared to any XP-G2 that has ever been measured in this way.
Just like djozz he only tested one sample though…
Even just assuming that the 1420lm is with a dedomed S4 XP G2, the 800lm on 1mm area die should still be better than the 1420lm on 2.1mm area of the XP-G2, right?
EDIT- ok so I read djozz’s post wrong, the one that is NOT higher than the XP-G2 is the XP-E2, the black flat IS higher than the XP-G2
When talking about XP-E2: “(edit:I was wrong here, after a suggestion by chouster, a quick calculation learned that an S4 XP-G2 reaches a higher surface brightness when at max)”
When talking about the flat black: “(edit: also higher than a S4 XP-G2)”
So that clears things up…
Now the question is, can I pay someone to reflow a bunch of flat blacks onto copper stars? plz
Yes, it increases just the same. This also the why you only need one precise luminance value and a standard lumens graph like the one from djozz. You can calculate all the the other values.
lumens/mm^2 is generally ok (for de-domed LEDs), but you need to be really precise! Also you can’t use this value to actually calculate the throw of light (you can do this with the actual luminance value).
Perfect, thanks.
Unfortunately I don’t have an integration sphere to compare the lux between LEDs…
Do you think just running them at 4A and picking the one that shows highest on my luxmeter will work just as well?
I’m not trying to find out the lumens, or the curves like djozz’s graphs, just the one with highest intensity, since they would all be the exact same led.
You don’t need special equipment. A stove top and a pie tin will do. Pre tin the star using a soldering iron and heat in the pie tin until the solder melts and the led settles into place.
Well, I think someone who’s done if for years will be able to do it better than me…
I don’t want some ugly burnt piece of copper, I like how clean the ones I buy are
Yeah I toasted a few but the learning curve is pretty steep and if you practice on the ones you want to replace it doesn’t come at any great price. Hint: it doesn’t take enough heat to burn the silk mask. Waiting sucks, I have a bunch of LEDs and mcpcb’s and the hardest part is remembering which direction to install them.
@ Enderman & The_Driver: in Germany the flat was tested at 250cd mm^2, but that was including optics. Without it should be even better.
@ Djozz: no worrie, no hurrie mate. Just make sure you get enough of them to satisfy my modding needs
It looks as if this Oslon will be able to take the pencil beam throwers a good bit further the the XP G2’s. :+1:
and without tint shift!! :+1: :+1: :+1:
I wouldn’t count on them reaching much higher values. Photographic optics like the one he used in the test have very little transmission losses (should be in the single digit percent range). The problem with his measurement of the LED without optic is that he didn’t account for any of the stray light from the LED. It bounces off of the surroundings and also hits the sensor of the light meter which makes the measured value higher than it really is.
Using an optic reduces the amount of stray light and the the much higher measured lux values greatly reduce the effect of any remaining stray light.
I would use 250-255cd/mm^2 as the baseline for any calculations.
Hey, interesting emitter!
Just requested a quote from RS (UK) for 5 pieces of Black Flat v1.2 5500K, but i read Djozz is waiting for v1.3 high CRI?
Either way, subbed to this thread…
