Texas_Ace BLF Calibrated Lumen tube / Sphere No math skills needed - Several spheres still available

He stretched a white plastic bag from a local store over the sensor. Very similar to what I did using some wax tissue paper.

I put brand new batteries in the Meter ( I have had low/crappy batteries give me High Lux readings before) and after many hours of trying different materials ……I tried the Walmart white plastic bag…. 1 layer stretched over meter shoved into the end of the tube :smiley:

Just curious, is the hole in the centering ring just perfectly sized for this light so only the very edge of the bezel is resting on it? (not blocking any of the reflector area)

I thought we had to hold the light through the hole, starting at roughly flush then move it up and down.

In most cases you have to hold it but some lights will rest on it. If you hold the ring up to the light you can see if it will block any of the reflector easily. If not then you can simply rest it on top of the ring.

It completely depends on the light you are using.

It is all pretty intuitive once you get it I think.

I see thanks for explaining.

How much smaller than the hole can the head of the light be without having too much light escaping around the open edges?

No it didn’t make any major difference, I tried all different scenario’s, light just thru the bigger cut out, a little lower, moved it around, nothing major a couple lumens, but if you go too low/too high then you see the lux drop like a rock… I even turned the centering rings over to the silver painted side and measured.

I’m not worried about 20-40 lumens I don’t build many pocket fondling EDC lights to care about it.

Your asking a ton of questions, but you should just wait until your tube arrives. It’s super difficult to put the answers into words. All your questions will be answered once you try it out.

It is one of those case by case basis type of deals. After you play with it you will see pretty quick the effects of using differnt sized rings or moving the light up or down.

As was said, pushing the light in too far or pulling it out too far can have big effects, the ring size is less important within reason.

You can make your own rings out of cardboard as well if you have an odd sized light. These are just some general sized rings that work with most lights.

Do you think lumen tube will melt if i test 15 minutes continually of flashlights that are 1000-17000 lumen ??

I have not tried it myself for that long, I really can’t say. My gut says it should be but with a very high powered light it is possible it could melt. I would simply touch the diffusing disk after a few minutes to see how hot it is to see if you should keep going.

Although I don’t know of any lights that can do 17k lumens for 15 minutes straight without overheating.

1000 lumens would be no problem at all.

TA, received mine the other day. Thanks for the quick turnaround…there is no way I would ever have been able to build so many of these in that time-frame. I just put out some feelers to some individuals who may have access to integrating spheres. One works at a USA based flashlight company and the other is at a streetlight test facility. I’m either going to see if I can get a couple of my lights tested with exact output numbers or borrow/purchase a light that has been tested. If this happens, I’m going to use this to calibrate mine, and you are more than welcome to use them. Of course, this is pending whether or not either guy pulls through. Thanks again.

Received mine yesterday. Have not had time to test it out yet.

Thanks for making these TA.

I see a need in the flashlight world that isn't currently being fulfilled on an affordable/practical basis. Would be nice if:

(1) xyz company would test a specific light that you mail in - then test it in an integrating sphere - then return it - for a reasonable fee

(2) a flashlight manufacturer would sell tested lights with a calibration sheet showing that particular light was tested in a sphere. That might cost twice as much (or more) than a normal production run - but would be worth it as a reference.

As you can imagine, the price range is huge. Some compact ones like the Labpshere FS2 cost several tens of thousands. Last year I was contacting multiple sphere manufacturers specifically looking for an affordable one, which wasn’t an easy task. Most of them ignored my emails. Lisun however was very helpful and also provided photos of details I asked about to make sure I was able to do flashlight measurements easily.

It did help that I didn’t need the spectro or software, even though some mfgs always bundle them together. After some back and forth negotation, this sphere with the required equipment (meter, standard calibration lamp, psu, shipping + VAT/duty) only came to the level of couple highend custom lights (<$5000). A tradeoff I’m more than willing to make. We are at BLF after all. The sphere itself is well below $2k.

Of course if you don’t buy a package deal with all the associated equipment from the sphere company, there’s a lot of experimenting and calibrating to do, just like with any DIY integrating sphere/tube/shoebox. If you’ve ever tried building one, you know. You can get very good results with making everything yourself, but usually the meter is the Achilles’s heel. Djozz has several good threads on the subject. Also, measuring flashlights is more difficult than omnidirectional bulbs. But as this is a hobby, I don’t consider the time spent doing this costing me anything. Rather a learning experience.

I disagree completely, I’ve gotten very good answers that have helped me understand more about this and know how to use it better when it arrives, that’s all I was after.

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Is that bothering you?
I’ve only asked a few questions not a ton, you’ve asked about the same number of questions today yourself. First time I’ve been chided on the forum for asking questions!!

I was thinking of a way to reduce this back and forth international shipping cost to Maukka drastically.

Maybe Maukka (I assume he has lots of flashlight parts laying around) could choose a suitable emitter and a reliable driver and wire it to a common battery (30Q) then record the levels in his sphere minus a flashlight body. Then he just mails that to TA. Wouldn’t the exact results be repeatable?

It’s also one way shipping of a thin envelope.

You guys would have to sort out the small details such as the size of the heatsink it’s mounted to and how long after turn on to take the Lumen reading. Maybe also how to hold the emitter to the sphere. So if Maukka says he measured this emitter/driver at 44lm, 160lm and 555lm then TA can measure in a couple of his tubes to get an exact correction factor.

Maybe you guys both have power supplies? Then you can use a set voltage and eliminate the battery as a variable.

Just a thought.

If the integrating properties aren’t perfect it’s better to calibrate using a light with a reflector, since that’s what the tube will be used for.

The S2+ on a med mode and the BLF348 are very stable so they’ll do fine.

edit: the power supply suggestion is good. TA could just send the head of an S2+ without a driver with leads hanging out from the MCPCB. If he has an accurate PSU we could just drive it at 100mA to take the battery out of the equation.

WOW! That's one heck of a great "Just a thought"! Big Thumbs Up, bud! :)

Not chiding. :innocent:

Let me know if you hear back, I will most likely be sending my lights in a few days but not having to ship international would be great.