There has been discussion again about coming to some sort of rough standardization for calibrating our meters so we are making reasonably accurate comparisons with each other. We’ve tossed a few ideas in the hat in the LED testing thread by n10sivern. This is to keep his thread from being dragged too far off topic as we discuss the logistics of getting this done.
I’d like to propose that we take up djozz on his idea to make a few lights that run about 25kcd, pre-tested by him and using them to dial our measurements in. I think he should make 2 each in cool white, neutral white, and warm white. He sells these in a set of 3 to the first 2 people. The first two recipients measure all 3 , post their results, and sell them to the next person on the list for the same price they paid plus shipping. This goes on until no one else wants a chance to use the kit to calibrate their meters and they can be sold off to whomever would like to have them permanently.
If you want to be considered please include the meters you can test with. Also your state or country so the final list can be organized to minimize shipping times.
I’ll update this post once I’ve had more time to think of logistics and am not typing on a cell phone.
The following is the list of things to measure and the procedure to follow. This is just the first draft and will be updated based on suggestions we have in the thread.
**Flashlight \#1 Cool White**
Starting Voltage of Battery:
Ending Voltage of Battery:_
Measurements for throw: (to be measured within 30 seconds of turn-on from room temp)
Meter:_ Lux:_ Distance:_ Calculated Candelas:_ djozz Candela Measurement:_ Your correction factor:_
Measurements for Lumens: (measured at 30 seconds after turn-on from room temp)
Flood Mode: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
Zoomed: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
**Flashlight \#2 Neutral White**
Starting Voltage of Battery:
Ending Voltage of Battery:_
Measurements for throw: (to be measured within 30 seconds of turn-on from room temp)
Meter:_ Lux:_ Distance:_ Calculated Candelas:_ djozz Candela Measurement:_ Your correction factor:_
Measurements for Lumens: (measured at 30 seconds after turn-on from room temp)
Flood Mode: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
Zoomed: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
**Flashlight \#3 Warm White**
Starting Voltage of Battery:
Ending Voltage of Battery:_
Measurements for throw: (to be measured within 30 seconds of turn-on from room temp)
Meter:_ Lux:_ Distance:_ Calculated Candelas:_ djozz Candela Measurement:_ Your correction factor:_
Measurements for Lumens: (measured at 30 seconds after turn-on from room temp)
Flood Mode: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
Zoomed: Device:_ Meter:_ Lux:_ djozz measured Lumens:_ Your correction factor:_
Good deal, I think you belong on the list. Can you let us know what meter or meters you can test? Also what state you live in if that’s OK so I can try to organize a list to minimize shipping times.
I have a HS1010A My other one I don’t know the name of. It came from an agriculture department (State of Michigan’s) It’s supposed to be calibrated but it’s farther off from the results that most people post than the HS1010A
I'm interested but would need some basic simple instructions on how to go about it all. Dr Meter LX1330B. It would also save costs if this was done on a country by country basis. Thanks for the idea and work put in.
Do you guys feel it would be beneficial to measure lumens in flood and zoomed mode to assess whether beam shape effects the measurements of our various lumens measuring devices? There’s speculation that the pipes favor throwers, and we could get a rough idea how far apart our measurements are from what is probably the most accurate setup of any member on the board.
First, a battery and charger are not needed, as the lights run on limited and 7135 regulated current, any 14500 will make the light run at virtually the same light output for almost the complete runtime of the battery.
To get to 25kcd in such a small light at 700mA, the led is a dedomed XP-E2. I use the ones I got for 50 cents a piece from Mitko. I do not have an easy source for other tint XP-E2's, especially a good neutral one, and the tint after dedoming will not be specified easily either.
You may want to correct your luxmeter readings for all tints from warm to cool, but most of us want to know the numbers for neutral and cool tints, and even in cheap luxmeters those are not that far off, a few percent.
It is convenient to keep a constant and measured flashlight as a backup for new projects (like when you get yourself a new luxmeter, or build a lightbox/sphere), so passing it through is not what everyone would want. The reference for my 'djozz-lumen' is a flashlight, not a luxmeter or sphere-conversion-factor.
That’s why I’m trying to keep it to only 6 lights for you to make, and we can pass them on after we get an idea how our meters and lumens contraptions compare. I suspect most of us have a few lights we’ll never part with that we can use to calibrate new measuring devices once we know what their output is with our tested meters/lumens devices.
I’ll be happy to send you some parts to do the builds, or even build a couple of the lights and send them to you to bring down the effort involved for you, it’d be worth it to me to be sure my measurements are comparable to others on the board.
Edit: You are correct, I forgot that these were going to be such low power builds, so battery consistency matters very little as long as they aren’t nearly dead.
I am interested in this, but i have no light meter yet.
So i hope how ever this will play out in the end, i will be able to be part of it when i finally get me one
And if you guys need some good cheap 14500, pick up the Windyfire 10A, i have them & they are great And according to HKJ the strongest amp wise performers so far.
MTN has them & Windyfire themselves have decent shipping prices to Europe.
As (for the given hemisphere) the sun on a sunny (clear) day (should be equally bringht to all, use lattitude adjustment factor if needed). instead of sending stuff around the world would it not be eayser to just agree how to the “test” the sun?
just a WAG
somthing like, place sensor at the bottom of a 6 inch ID, 3 foot (white/black) tube and aim it at the sun you meter should read X
If the sun is too bright in the above test make it a 3 inch tube (or somother agree upon adjustment) and
BADA BING at least folks on the same hemisphere should get the same reading, and if not I bet a lattatude adjustment factor can be found.
How about a cheap reflectored 18650 light, say xml-2 run at a low output of an amp or so. As long as the lights are of a consistent quality, it should be doable. Use the same tint emitters, same drivers, same host, same reflector. Maybe an op reflector to smoothen the beam out.
Low output so cells are not a factor, op so beams are smooth and slight variances are not a factor, same tints so tint is not a factor...
We don't need a nice tint or high output for this test, just consistency. A cheap $10-15 light. That way you can just buy one and have it to reference to for a new meter and compare results with others.
Oh, LX-1330b here, and it seems to be pretty close to ANSI rated lights I have tested
