Thanks for doing this maukka. Looking forward to checking my current calibration (best guess with a zebra light).
Well at least there will be 20 or more BLF members with calibrated spheres now.
I have already seen that rated lumen’s is not the same as actual OTF lumen’s. I did a led swap in a Sunwayman V10R ti light yesterday.
I swapped out a Nichia 219c D240 for a AEDe 90 cri Samsung LD351D and gained 100 lumen’s with out changing anything else. I would have never known that before. Having it calibrated will make it even better for testing. Thanks again maukka. :+1:
OTF just seperates the raw led measurements from the led plus reflector, lens, driver, etc… losses.
Manufacturers ratings are OTF, but they are usually very “optimistic”.
I swapped the xpl out of an On The Road U18 and put in a sst40. It went from 690 to 845! I’m guessing it’s due to differences in forward voltage and overall efficiency.
BTW, the U18 is rated at 1090 lm even though it only draws 2.3A. :person_facepalming: It’s still bright, though. :+1:
Yeah rated (printed on the box) versus real life actual out the front lumen’s. I think a lot of these company’s just assume if they put x led in and drive it with y current then they get z lumen’s and that’s what they put on the box. Never taking into account any losses. On a small light driven conservatively 20% losses isn’t gonna make much difference but when you start driving a led harder the losses are huge. 20% of 300 lumen’s is a 60 lumen loss but 20% of 10,000 lumen’s is 2,000 lumen’s. Changing wire size can even make a huge difference. We have all seen things these company’s do to cut corners or if there there x bin leds run out, they just use y bin. Or if drivers start burning up they just reduce current in they next batch.
So yeah that was my point what’s advertised or printed on the box will more than likely never be what’s actually coming out the front of the light. Even if you accounted for all the losses and knew exactly what a x bin led made at y current, you would still have cree’s margin of bin’s. You would have to rate the lumen’s on the low side of the bin to not be lying, because out of the thousand’s of lights they make their still playing the bin lottery. There are a few exceptions to this though that get close, probably because of the bin lottery.