LED test / review – Osram OSTAR Projection Compact LE UW Q8WP – Black Flat's big brother, very high luminance at higher flux!

The draw current was in all three measurements 4.00 Amperes (lab power supply and measured with clamp meter). In general I look closely to get the absolutely same environment and measurement conditions also in case of repetitions. The 105c limits the max current.
The XP-G2 seems to be underdriven, but originally (in domed state) it was only bin R5. Without dome the flux is another measured 27 percent less so it equals more to Cree flux bin Q5 or R2. Against it the Q8WP is a lot more efficient!

Thanks for the test.
EasyB is correct that if your luxmeter is right in front of the LED, the area that should be used for the calculation is the front area, which would be 1.55*1.23 = 1.9065mm^2

You can see in the real world test in your flashlight that the Q8WP still gets higher cd than the G2.
However, since it also emits light to the sides (which then get collected by the reflector but don’t add to the intensity) you end up with a worse cd/lumen ratio.
If all you care about is throw, cd/lumen doesn’t really matter as long as it still has higher cd.
.
Taking the front area of 1.9065mm^2, we can do 153.9/1.9065*3.23 = 260.73cd/mm^2 which is just slightly below the Black Flat but still better than any cree LED.

You can see this reflected in your real world test, the Q8WP gets 1.336 times higher intensity than the XP-G2.
At 260.7cd/mm^2 it is 1.321 times higher than the 197.3cd/mm^2 of the XP-G2 (as seen in your table).

I’m not exactly sure why your XP-L HI did better than the G2 in your real world test but worse in the cd/mm^2 table, probably because you used two different XP-G2s, but it is still the case that the Q8WP outperforms the XP-L HI in both the real world test and in the cd/mm^2 measurements, suggesting that the 260cd/mm^2 is correct.

Yeah, but only because of the bigger (side) LES and higher efficiency than the old shabby R5 XP-G2.
If I had used a dedomed XP-G2 S4 2B the intensity would be much higher than of the Q8WP, at approx 73 kcd or so - despite smaller LES because the XP-G2 doesn’t emit any light directly to the side.

Gradually I have the impression that the (also my) method to get the luminance is wrong. As far I understood the luminance depends on solid angle (Steradian), the light flux in this angle and the LES. If the brightness is measured and divided by the LES, we get such result that not depends on the angle of emitted light.

The next days I test another XP-G2, maybe in S2 bin. The dedomed XP-G2 S4 2B of my chart is broken and I am not sure about the by Hank newly discovered old XP-G2 S4 that they are as good as the old ones…

You’re right, the side light does seem to affect the emission profile a lot, especially at about 45 degrees, since it is very different from the no-dome black flat or synios LEDs.

I am still unsure of how putting this LED in the flashlight affected your lux readings though, since the reflector on a flashlight collects the side emission more than the forward emission of an LED.

I would suggest using a lens instead, to just take the front view and emission of the LED, maybe that will give more accurate comparison between LEDs.
It will also be easier to get a consistent lux reading since using a lens will give a nice uniform die projection rather than a spot with a corona.

Thanks for testing this led, it was on my list but you keep relieving my BLF-workload :smiley:

Some thoughts.The light emitted to the side does hit the reflector but predominantly the deepest part that gives a much worse hotspot projection than near the edge of the reflector, and does not add much to the cd of the hotspot.
It is a matter of choice if you use a reflector or lens for testing throw, I assume the optimal emission profile for both is slightly different.

Imho this is nicest looking emitter I ever seen. To bad about performance :frowning:
Thank you very much koef3.

Important notice:

I updated the luminance values for all LEDs shown in test chart including Q8WP. After several 'real-life condition' measurements in flashlight optics (SMO reflector) this LED has a very high luminance at much higher light flux than Black Flat which makes it very interesting for ultra-long-range flashlights with more output!

To ensure more realistic values for 'real-life' conditions (flashlight use / secondary optics) I established a new testing method to determine the luminance with a SMO reflector. All upcoming and already existing tests will use this method!

Updating of my other tests will be done in the next hours / days.

At this point big thanks to everyone who helped me out to establish this new test method and answered my questions about this! :)

Interesting, so my assumptions when I found this LED were correct after all. This is a special LED. Thanks Koef3 ;).

Thanks Koef3,

The Driver and Enderman will have to change their emitters now :laughing:

So we have excellent results here but with higher current draw… No I don’t wan’t it it in single cell light…

But if there would be good and reliable buck driver with 9.6A draw I would think about adding additional 18650 tube to my lets say special edition lights.

20% lux performance with larger die than old g2s42b is not a joke… And it is best looking emitter ever imho.

Well, my big thrower was designed for this LED, but it’s just too much work. I don’t want to wait for the light again, currently. Maybe, when higher Bins become available. I think Enderman told me about a slightly updated version of this LED a while ago which doesn’t have the lowest bin anymore.

There are good buck drivers for 9.6A, but they have a large diameter.

Because of the low Vf you could just use a LD4 linear driver. It’s compact, works very good and not too expensive!

Haha :slight_smile:
I’m still gonna go with the CFT90 for the syniosbeam, 5000 lumens will still be pretty amazing.
As for throw, the black flat still is a bit better, especially since I don’t have any 10 amp buck drivers around.

Aside from super-throwers, Emisar D1 with 18350 would be a nice host for it. :smiling_imp:

2 would regular 3d printers be able to make centering rings for this?
BTW, I see them available from RS-online and Taobao:

https://item.taobao.com/item.htm?spm=a230r.1.14.18.753b32c5F9Z5d3&id=563939609715&ns=1&abbucket=8#detail
https://item.taobao.com/item.htm?spm=a230r.1.14.3.753b32c5F9Z5d3&id=546416566690&ns=1&abbucket=8#detail

Prices could be worse.

I wonder how would KW CSLNM1.TG do…similar die size to the Blackie, newer, marginally better thermal resistance, same thermal pad size.

Koef3, myself and some others in the German TLF forum got them through a Taobao agent last year.

Optical center is not package center, die looks shifted? This would make centering problematic with xp boards.

I disagree with this emitter being inefficient.
Now I don’t have hard numbers, just your charts, so my conclusions are fragmentary, but they don’t show inefficiency.

If you want to light-up an emitter surface to high level, it will become inefficient. That’s true for any emitter.
What is special about Q8WP one is that it enables you to overdrive it much further than others. This makes it’s more modest modes look inefficient….

Overdrive XHP35 HI E2 to 170 cd/mm². It delivers ~60 lm/W. Overdrive Q8WP to the same luminosity - you get ~80 lm/W.
Saying the same differently: drive it with reasonable W/mm² and it delivers reasonable lm/W. This is a small emitter and won’t deliver high lumens efficiently. But it doesn’t mean it’s inefficient - it means it’s small.

It would make a fine LED for multi-emitter throwers.

The XP-G2 S4 2B de-domed has a luminance of 142.9cd/mm^2 at 2.8A and has a 2mm^2 die.
The Osram Q8WP has a luminance of 121.8cd/mm^2 at 2.8A and has a 1.91mm^2 die.
So the Q8WP is smaller, but still has a lower luminance at the same (medium high) current.

If you compare them at 6A, the Q8WP starts to edge ahead slightly (205.9 vs 200.1) because of it’s much lower Vf (3.51V vs 4.35V !) coupled with the much lower thermal resistance. The difference should be much bigger. We need betters bins.

This LED definitely has a lot of potential!

Why are you taking current in efficiency calculations? I think that power is more interesting. And thanks to lower Vf, at the same input current, Q8WP uses (much) less power.

Because it’s more relevant for many lights where you can’t or don’t want to switch out the driver.
The real efficiency is of course much better compared to older LEDs.