Ceiling bounce lux test, U2 showing 24% less lux than T6
Hi, wanting to check with others in the forum that I am doing the ceiling bounce light test correctly. Have 3 different model Chinese XM-L bike lights I’m testing, 2x T6 and a U2. I sit the lights one at a time on a bike light box that came with one of the lights and have the light meter right beside the light. This box is on the ground so 2.4m to the ceiling. Using the lounge as the room is bigger than other rooms. All the light beams hit the ceiling and not any walls. I have each light on for 5 minutes to allow the light housing etc. to heat up, no fan used and write down the lux reading for every minute.
U2 1 min = 21.2 lux, 3 min = 19.7, 5 min = 19.6.
1st T6 1 min = 25.8, 3 min = 24.6, 5 min = 24.3
2nd T6 1 min = 27.6, 3min = 25.8, 5 min = 25.1
Theres a bunch of things that lead to your Lux comparison differences.
- Reflector quality
- Front glass (AR coated?)
- Optic alignment
- Drive current
- LED bin
- Heat transfer out of the LED.
If your concern is "Is this actually a U2 bin?" my advice would be to order a U2 from cutter.com.au and swap that in to each light to check for significant differences. Theres a good chance they aren't even T6.
Second the request for links. Those don't look like anything I've seen before and the builds are quite interesting. Too bad you don't have the MS version to compare as well.
Originally Posted by odtexas
As Znomit inferred, a lot of factors play into lux bounce readings. I have a feeling there is likely an inverse relationship between bounce distance and beam spread. Just a theory of mine. No way to know for sure until I buy one of those meters. Anyway, all good stuff, please continue.
edit: I'd be interested to see the readings with a fan on low as well.
well, is the U2 perceived brighter ?
that's what most people, want for difference.
The Lux meter, does measure an average visible spectrum,
while a U2 bin, will have more in the blue spectrum,
what it might not account for, as such, will show lower output.
for most parts, it's also the bin and power difference of the circuit.
an U2 will also have worse color ,....
give me a million candles, I'll be fine with that color.
Thank you for your input, I find this forum very helpful in learning what I can with bike lights etc. The 2 lights in the photos are new models released late May. Left one is from Ostar, SG-N1000 which I sell along with the older version SG-B1000. The one on the right is from Inton, B1002 I think is the model code which is a 3.7v system. As these are chinese manufactures so high ratings. Factory rated 1000lm and Inton 1000+ even though they are proberly around 650 -700lm. I will be testing the lights with a fan when I get a chance to see when the Inton light starts dropping in lux and taking beam shots to compare the difference. http://www.artprint.co.nz/bikelights.htm my site with the specs on Ostar lights. I am told by the manufacture 2.5A forward current. Yet to test myself as not sure how to do it. Both lights are currently on Trademe http://www.trademe.co.nz/Sports/Cycl...0596-3983-.htm The hexagonal light Ostra SG-N1000 has a smller reflector than the older SG-B1000 giving a tighter beam softer hot spot less spread with a bit more throw. The SG-B1000 sometimes washes out the track in front of your with it's intense small hot spot. I usual run with 3 xml's and find it a lot easier on my eyes. I'll include a beam shot photo of the 2.
Beam shots of new SG-N1000 and older SG-B1000
I used http://reviews.mtbr.com/blog/lights-...r-measurements as a guide to setting up my ceiling bounce light test. The 5ft from ceiling they used I thought may have been too close for my test as my feeling was the light with the intense small hot spot will bounce back directly onto the meter more than the other two lights. Also moved from a small room to a larger room so the whole circle of the beam is seen on the ceiling. Wondering if making up a special box for testing will do a more actuate job. Say made from say mdf board painted matte white with two holes in the bottom for light and meter. Ceiling in the shape of a v so the light doesn’t bounce directly back to the meter.
rule of thumb,...
2x handlebar, 1x helmet (2x ~600+, + 1x 500+ is a good start)
the one with the biggest fins wins, (most of them are under dimensioned)
lowest color, highest CRI ( unless you like neon, and are colorblind)
voltage, higher is better, means lower current,... 11-15V is groovy
once you got enough light, you can spread it,... ( flood,wide, lenses, diffuser , etc)
get a decent battery and charger
any light with those, XPG, P7,MCE, or XML, will do fine.
otherwise, a single XML, even if they claim 1 million lumen, will not do.
my recent yardstick, is 2x XML at 2A , around 1040 lumen (pi x thumb)
did have it running at 2.5A and 3A, just gets more hot , then brightness,...
at 12.5W 1040 lumen = 83 lm/watt once hot, more like 965 at 12W,
it's just a test, and conclusive, driving an XML over 2.2A is not practical.
having a power meter helps too,... other LED's do 65 lm/w , and the once with a too smaller heatsink,
and to much current, go south, 55- (minus/or less) is very common .
keep the octagone ones, have 3 be happy.
yes I am liking the hexagonal ones, only using one on the helmet and have been thinking of swapping the two older models on the bars to hexagonal ones too. Running three battery packs but at some stage soon will look at getting a bigger battery pack and Y cable for the bar lights. Still like a battery in my back pack for the helmet light when I separate from the bike whether it be voluntary or not.
Looks like the Inton light is only a T6 not a U2 as seller has just added this to some of their listings. “I Asked the factory engineer a question, about the statement our fellow seller is saying about the T6 bulb against the U2 bulb. THIS IS HIS REPLY beary xiong (4:16:27 ): dont believe that, his test without any technical certificate...and thats total impossible! Our U2 bulb is infact a T6 but when tested, the best performing 10% are rebranded U2 And are sold as 1100lumens, so his home made test results,as the engineer states,: IS TOTAL IMPOSSIBLE”
So the chinese manufacture is rebranding them as U2. They could have the U3 availble before Cree does
I use CS3 and it strips the Exif data from the file when using "save for web" for saving animated gifs. Only the later versions CS4 & CS5 you have the option to show or not. Trademe also strips the Exif data. I'll attach a jpg which should have the Exif data. At present we only sell the lights within NZ.
no EXIF data listed on the photo
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