Can we buy an integrating sphere?

How much does an integrating sphere cost? We are constantly guessing how many lumens lights really produce. All these conversion factors that we fabricate may be close but can't be considered reliable since there are so many factors that effect how much light actually goes out of the front end of a flashlight. We could also put an end to which manufacturers overrate and underrate their lights as well as test for variance within same lights and/or emitters. I would love to see actual numbers on custom and modded lights. Wouldn't it be nice to have an objective way of measuring rather than relative comparisons?

From searching on the internet, these instruments look like VERY expensive lab equipment. With that said, with the number of users on this forum, perhaps we can all pitch in for one. Everyone that donates X amount can have a free test of their light of choice. Additionally, people can send in their lights to get tested for a small fee, which can be used to suport the site (hosting, bandwidth, etc.) Is this plausible? Administrators or long time members could decide who would be responsible for this service.

What do you guys think?

*EDIT: I found one site selling integrating spheres. They were going for about $1500. It would take 75 members donating $20 to get to $1500. Doesn't sound so bad. I'm not sure if its the right kind we need, but it gives a ballpark estimate of how much these instruments cost.

I am not a lawyer but arrangements like that usually require lots of clarity and written agreements up front because of all the things which can go wrong. Who gets to keep the thing. What if he does a poor job of maintaining it or if it breaks and it takes money or a lot of his time or both to get it fixed.

Would the person who keeps the thing (I bet it ain't real mobile) be willing to run tests for the hundred and possibly thousands of requests which will be coming in (if we get a lot of buy in) as his contribution for having access to it. Being able to run his own tests would be fun for a few weeks, but that fun may wear thin after a few weeks and the requests for tests will be coming in for years.

If he gets tired of it or sick of it, who gets it next? Who pays for the transfer and insurance? You'll need to set aside funds for these contingencies. Does anyone know how much?

Also, I don't know that every owner of a Fenix L1X-XX will want to get their light tested. Most would be happy to read someone else's test results for the same model and assume theirs is similar. A few custom makers might want their lights tested, but how many of those are there really. I'm guessing it's just not going to work out money wise or time commitment wise when all is taken into account.

Think of all the angst which is flying around now for the DX Jetbeam CLE sale which is a few weeks late. Can you imagine the anguish there will be when it takes 4 years to test 2000 lights through an integrating sphere 500 people have part ownership of (and only one person running it, probably with kids, a job, and an unhappy wife, and a desire to actually build a few lights).

The current system of using home made of light boxes and approximate conversion factors between those boxes, Quickbeams Q-lumen measurements from FLRs, and the few calibrating integrating sphere tests we have is probably about all that's practical at this time, IMHO...

that's not bad really, there are a lot of members who have spent more than that on 1 light. I'd be willing to bet we could get a lot more than 75 people to donate also.. great idea... I'd donate $20.

That's a great idea. I giggle all the time at the lumen figures being thrown around and it would be nice to finally know. I'd be happy to donate towards this.

I volunteer to run testing,

I think the idea is silly... :nana:

But it brings up a more interesting question. How much would you or anyone else be willing to pay for the SERVICE of an integrating sphere? This will never work as a group owned kind of thing. But if the thread is able to generate enough interest, and that interest is the kind that is willing to PAY, then I'm sure an enterprising capitalist will step up, buy an integrating sphere, and measure what you want...for a fee.

Minjin said:

I think the idea is silly... :nana:

But it brings up a more interesting question. How much would you or anyone else be willing to pay for the SERVICE of an integrating sphere? This will never work as a group owned kind of thing. But if the thread is able to generate enough interest, and that interest is the kind that is willing to PAY, then I'm sure an enterprising capitalist will step up, buy an integrating sphere, and measure what you want...for a fee.

Click to expand...

How much does it cost to get a light tested? Maybe we could get some kind of group discount if we sent in a large group of lights.

Here are some of the problems that can occur.

1) The IS guy (Integrating Sphere guy) is going to have to commit alot of time into this. He's going to have to deal with PMs, emails, receiveing lights, shipping lights, etc very often.

2) The person who sends the light should pay shipping both ways. And if the light gets damaged, stolen, lost then thats not going to be a happy CPF member.

3) What if something happens to the IS guy & no one hears from him?

Minjin said:

I think the idea is silly... :nana:

But it brings up a more interesting question. How much would you or anyone else be willing to pay for the SERVICE of an integrating sphere? This will never work as a group owned kind of thing. But if the thread is able to generate enough interest, and that interest is the kind that is willing to PAY, then I'm sure an enterprising capitalist will step up, buy an integrating sphere, and measure what you want...for a fee.

Click to expand...

I agree. Someone out there can actually make something out of this. It can be like a business investment. Who knows...

There was a thread just like this, last year or the year before.

I believe McGizmo actually has one. He used it to accurately measure the output of a particular light, and that light was part of a "calibration passaround," in which members who have their own home-brew light measuring boxes used the light to see how accurately theirs measured.

The concerns raised are legitimate ones regarding the "shared ownership" of the integrating sphere (IS). I had in mind however, that the money that went towards the IS would be a donation, and therefore it wouldn't be owned by the donors. But that still leaves the question of who would own it. I'm sure the founder of this forum would not want to be testing and sending back lights daily.

Let's frame it a different way. Say I buy the unit myself and offer testing as a service. I wait until I have X amount of willing customers @ Y amount of dollars that would equate to the price of the IS. I don't ask for customers to start sending in lights until I have enough demand to cover the initial cost of the unit. Sort of like an interest check.

The question is... how much would you be willing to pay for a TRUE lumen count of your light/s? Another website was offering this service for all different sorts of lights. I couldn't believe the price and maybe I was reading it wrong but it was something close to $300! I was thinking something like $10-$15 + $3-$5 per additional light + 2 way shipping. Comments?

great points... might be much smarter for someone to just buy one as their own, and charge a small fee for testing.

If I could buy one for $1500, and I knew it would last awhile, and I knew there would be enough "business" to make it worth buying, I would. 150 lights tested at $10 each would at least cover the cost.

Not a bad idea at all IMHO. We've seen enthusiastic people that graciously spent countless time for a given task. Silverfox and Quickbeam come to mind, and I'd have no problem donating $20 to the cause with no strings attached to someone like these guys for accurate and reliable lumens testing.

I think EXACT lumen ratings are completely unnecessary for the daily user. If the light gives you enough light for your tasks, great. If it throws far enough for your needs, good. Does it matter if your AE 24w is 'around 1200 lumens' or 1323.33 exact lumens?

If your eyes can't tell if a MkIIx on high is brighter than a L1D CE on high, does it really matter if it is XXX lumens difference?

Of course, if there was way to work it out, it is a 'nice-to-have'. But all that sending to and fro and risk of lost postage isn't worth knowing the exact lumen figure. Quickbeam's DIY type litebox is more than enough to get a ballpark figure.

I love doing runtime tests and other calculations to measure my lights' performance etc... but getting exact lumen figures isn't completely neccessary for me. Just like exact battery runtime to the millisecond isn't neccessary for me as well.

But if there's something worked out, donating some moolah for a good cause shouldn't be too much of a problem

Hello Supernam,

Here are three threads that you may find informative on this subject.

Thread 1
Thread 2
Thread 3

Tom

If it was owned by CPF it could be sold if anything happens and the money could be redistributed to the original donators.

SilverFox said:

Hello Supernam,

Here are three threads that you may find informative on this subject.

Thread 1
Thread 2
Thread 3

Tom

Click to expand...

Thanks Silverfox, I had not realized this had come up before. The same questions came up in the previous threads. From reading those threads, to me it seems that it would take way more time and money than just buying an integrating sphere. I'm assuming we would want to be able to honestly remove the qualifier "estimated" from our lumens rating. We already have a good tool for estimating lumens.

The lightbox described at flashlightreviews.com is a very good lumen estimator. It also has the advantage of being easy to build so anybody who wants to can repeat the measurement and report the results here at CPF.

http://www.flashlightreviews.com/features/lightbox_output.htm

I think a better idea is for a CPF member to buy one and offer the testing service to all members.
Say for a small fee of $10.00 + materials (batteries) for each light you can have the output certified. He would only have to do 150 lights to pay for the thing. I wonder if a guy could get 150 people to line up like a group buy to have their lights certified?
Hell If I could get 150 lights lined up for certification I would do it.
Now that is a cool idea. Having a certified output certificate. This would possibly increase the value of a flashlight. Manufacturers could send in their lights to be certified sort of like the CSOC does for chronometers in switzerland. How much would you willing to pay for a light with a certified output instead of a manufactures claim? A bit more I would say. This turns the IS into a moneymaking venture and not something that 100 people own, which is a very difficult thing to manage.

The other thing to consider is that you can actually make your own IS pretty easily. Using an empty milk carton and a calibrated light meter. Once you have a known certified and calibrated light source you can then do relative measurements which are very accurate at a much smaller cost than $1500.00.

There is a thread somewhere where there were a series of lights being passed around which were certified in an IS to determine their output so people could check their light meters against the known lights. It may still be going around.

To make a long story short since you are really just making relative measurements you can set up a milk carton IS and have great results for a fraction of the cost of an IS.

yaesumofo

Hello Art,

I think that if you really want to know the output of a light, it is worth the $300-400 to have it tested. When we had our Light Meter Benchmarking lights tested, I was able to get a discount from the laboratory. The bill came to just under $1500 for 5 lights.

I was surprised that in spite of all the interest in having real numbers, MiGizmo and I ended up paying a good share of the cost of those tests. Some people freely donated, but others didn't.

I was also surprised that it took the laboratory a whole week to test the 5 lights. It seems that the Integration Sphere calibrated source is calibrated for incandescent lights. Conversions need to be made when you introduce LED lights to the Sphere. The laboratory insisted on getting repeatable results, and it took a lot longer than they planned.

I should also point out that there is no standard to follow when testing LED flashlights. I spent quite a bit of time talking to the laboratory going over the test plan. We finally were able to develop a procedure that the laboratory could reproduce with ease thus insuring conformity between all the tests.

The acid test of how well we set things up would be to send them the lights for another round of testing and see if we come up with the same numbers. When I have a spare $1500 laying around, I may consider it.

The "home brew" Integration Spheres seem to give a pretty close approximation of what is going on. People have used a large globe, a 5 gallon plastic bucket, a styrofoam ice chest, and of course the milk carton. The classic is the ceiling bounce test, but it is not transferable.

The problem with the "home brew" set ups is that no one wants to pay the big bucks for a good light meter that is accurate across the broad spectrum of light. I seem to remember that they were running in the $1500-3000 range. I would find it a little strange to hook up my $2000 light meter to a milk carton for a lumen estimate, but I am just a little strange that way...

Tom

I remember somebody in the past made a discount offer to CPF. I think it was something like a flat $240 for the setup etc, then an additional $35 for each light they tested. This still seems like too much to me, but it was less than the regular price.

One thing to consider. Just because we get the lumens rating for one LED light does not mean we have a representative number for all, or even most of the same model of lights. We could have the tested runt of the litter, or maybe a "ringer" from somebody who got lucky.