WTS: Calibration lights for DIY integrating spheres / lumen tubes - 64 € -

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maukka
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WTS: Calibration lights for DIY integrating spheres / lumen tubes - 64 € -

After some interest from people wanting to calibrate their integrating spheres / lumen tubes I decided to make these little calibration kits available. For 64 euros you get two lights shipped anywhere in the world and you won’t have to rely on manufacturer or reviewer ratings, which might vary as much as 20% between samples even in the same batch. Read on for details.

As of 20.7.2018 I have ordered enough lights for 40 sets out of which about 20 has been tested and shipped. More will be made available as long as there’s interest and I am able to find reasonably priced suitable lights

The lights

For the calibration kit I’ve chosen the BLF348 and Convoy S2+ as they have a very consistent output (S2+ on low and mid). In my testing the output of the BLF348 stays within +/-1% regardless of the NiMH battery used between several measurement rounds. Same goes for the 7135 regulated Convoy, it doesn’t really matter which 18650 is used and the repeatability makes them perfect for calibration.

The lights have also been chosen to have different color temperature and CRI. While the BLF348 is neutral white (4500-5200 K) and very high CRI (Ra >90, R9 >80) the S2+ utilizes a cool white XM-L2 (~6500 K) with a low CRI of about 70.

This should give you two good data points to check whether your lux meter is affected by the differences in the spectrum. If the difference is large, you might want to use a different correction factor depending on the light being measured.

Total price for the kit with two calibration lights and data is 64 euros.
(PayPal will handle the conversion for you if you’re not in the EU)

First shipments should be ready to go out the door within two weeks while I wait for some S2+s to arrive.

Payment is done via Paypal (goods and services).

The price includes shipping anywhere in the world. I will send the lights without their original packaging padded in an envelope. This is due to the 3 cm limit for envelopes. Shipping time will be approximately 7-12 days to most countries. 17 days to the remotest areas.

There will be no tracking

If you need tracking the cost will be 87-100 euros depending on the country due to the high price of shipping packages from Finland.

For disclosure, the total price consists of 30 euros for the measurements and generating the data. Everything else is to cover the cost of buying the lights, shipping, packaging and paypal fees.

If you are in the EU, you can also send me your own lights to be measured. The cost of lumen measurement is 20 euros for the first light and 10 euros for any additional ones. You pay for shipping both ways. Remember that shipping boxes out of Finland is very expensive, especially if they have to be tracked.

In this case you can also request which battery should be used for testing. Do not send me any batteries. I have a wide range of 18650s.

While I already have procured some BLF348s, I’m still waiting on the Convoys. Let me know if you are interested and I’ll order more as needed.

What you get

The measurement report contains luminous flux in lumens at 0, 30 and 60 seconds as well as various measurements from the hotspot such as intensity in candelas, color temperature, tint and spectral data in image and text format.

The equipment used for calibration

The calibration lights have been measured in a 50 cm Lisun Group integrating sphere using an X-rite i1Pro spectrophotometer. The sphere was calibrated using Lisun’s SLS-10W standard light source. This is the setup I use in my reviews.

Sphere album: https://imgur.com/a/EbqM3

About spheres

The problem with calibrating an integrating sphere based on a flashlight that you have and some reviewer has tested is the big differences in LED bins and driver component tolerances. After measuring 10 BLF348’s from the same batch, I found output differences as large as 15%. Same goes for a seemingly reputable manufacturer’s specifications.

The point of a calibration light is that you measure the lux from your sphere using a light with a known output and then divide the given lumen output with the lux value. This gives you the correction factor which is used when measuring other lights.

For example, you get a calibration light which outputs 34 lumens. You measure its output in your sphere and the meter reads 100 lux. This means your correction factor is 34/100=0.34 which is used to multiply any subsequent lux readings to convert into lumens. A light that reads 500 lux is 500*0.34=170 lumens.

For information on how to make a DIY integrating spheres check out threads by djozz and JoshK. The widely used lumen tube uses PVC plumbing pipe, the latest thread on the subject is by Texas_Ace, which was also later calibrated by lights I tested for TA.

Please note, that the biggest problem with these devices arise from lights that are especially floody or throwy. If your lumen contraption is not integrating the light well enough, the numbers will be too high when measuring throwy lights. This is why it’s very important to try and diffuse the light as much as possible before it exits the sphere/tube and hits the meter. Matte surfaces, baffles and diffusers are your friends.

Edited by: maukka on 07/20/2018 - 15:28
maukka
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Interest list:

1st batch (estimated shipping: 20.7.)
1. emarkd shipped
2. yasenf shipped
3. Bob_McBob shipped
4. moderator007 shipped
5. SKV89 shipped
6. teacher shipped
7. shirnask shipped
8. Terry Oregon shipped
9. peabody shipped
10. Billy X shipped

2nd batch (estimated shipping: 29.7.)
11. Fady shipped
12. nkresho shipped
13. Micael shipped
14. iosala shipped
15. jmm244 shipped
16. vestureofblood shipped
17. KawiBoy1428 shipped
18. ImA4Wheelr shipped
19. JasonWW (S2+ only) shipped

3rd batch (estimated shipping: 6.8.)
20. Muto shipped
21. dmsoule shipped
22. slimkango shipped
23. Pezo shipped
24. fsvendsen shipped
25. Glow_Worm shipped
26. miswas shipped
27. toobadorz shipped
28. Mark M shipped
29. Hoop shipped
30. run4jc shipped

4th batch (estimated shipping: 17.8.)
31. Newlumen shipped
32. leroycp shipped
33.
.
.
.
40.

Rest
41.
.
.
50.

djozz
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Very cool offering maukka, for an extremely reasonable price! That should further reduce measurement errors among the BLF community.

link to djozz tests 

“I used to think that top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that thirty years of good science could address these problems. I was wrong. The top environmental problems are selfishness, greed and apathy, and to deal with these we need a cultural and spiritual transformation. And we scientists don’t know how to do that.”   (Gus Speth)

Agro
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Great, thank you for doing that. Smile
I’m not yet into building my sphere, but availability of calibrated lights is superb for the community.

Out of curiosity, you provide quite a few properties of those lights. Is everything except for flux measured at 0 seconds?

maukka
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Agro wrote:
Out of curiosity, you provide quite a few properties of those lights. Is everything except for flux measured at 0 seconds?

On the bottom of the measurement sheet it says:
“Intensity, CCT and CRI values measured at 30 seconds”

Should probably make it bigger Wink

yasenf
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Interested.

Agro
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maukka wrote:
Agro wrote:
Out of curiosity, you provide quite a few properties of those lights. Is everything except for flux measured at 0 seconds?

On the bottom of the measurement sheet it says:
“Intensity, CCT and CRI values measured at 30 seconds”

Should probably make it bigger Wink


Missed that because it was on a picture.
Thanks for clarification.
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yasenf wrote:
Interested.

Added you to the list and will PM you when your kit is ready to be shipped. No need to pay anything just yet.

emarkd
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Bump. With all the drama around here lately about calibrating lumen tubes I can’t believe there’s not more interest in this offering. Lots of us have measuring devices – group-buy sphere or tubes, homemade boxes, whatever – and want them to all yield comparable measurements so we can have more meaningful discussions. This is the best way to accomplish that goal, and offered for a very fair price.

Bob_McBob
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Really happy to see this idea coming to fruition so quickly. I’m definitely interested in a kit. I agree with emarkd, this should have way more interest given all the recent output measuring drama!

moderator007
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So 64 euros is $71.62 US dollars right? That’s what a online calculator came up with. Well I used another one and came up with $75.18 US.
Could you clarify what the price would be in US dollars please. I’m pretty sure I’m in for the set just don’t know what the Paypal payment should be.

Bob_McBob
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moderator007 wrote:
So 64 euros is $71.62 US dollars right? That’s what a online calculator came up with. Well I used another one and came up with $75.18 US. Could you clarify what the price would be in US dollars please. I’m pretty sure I’m in for the set just don’t know what the Paypal payment should be.

It’s $75.17 USD right now. You’ll probably pay around 2.5% on top of that for the currency conversion from either your card or PayPal. The PayPal payment will no doubt be in EUR so there is nothing to work out.

maukka
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Just choose sending euros in Paypal and they will do the conversion (with their conversion fees like Bob_McBob said). If you want to pay in USD it’s $78.

I will take cryptos (BTC, ETH, LTC, MIOTA, VET) as well.

moderator007
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Alright sounds good to me, if pp does the conversion. I’m in for the set, just PM when their available. Thumbs Up

Texas_Ace
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Very nice, these as the same lights I used to calibrate my own sphere. I just wish I had had them a few years ago, it would of made my life SO much easier. Well worth every penny.

Plus there is a lot of time involved with taking all of those measurements for each light.

SKV89
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Thanks for doing this. Please put me down. I’m glad the BLF348 has a duv of -0.0025, which means it’s the old batch and not the current batch I just bought with slight greenish tint. Instead of just giving us the 30s lumens. Can you also give us the startup lumens for these?

teacher
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I am in maukka, thank you. Smile

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shirnask
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Interested

Terry Oregon
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Count me in.

 

peabody
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Interested

maukka
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SKV89 wrote:
Thanks for doing this. Please put me down. I’m glad the BLF348 has a duv of -0.0025, which means it’s the old batch and not the current batch I just bought with slight greenish tint. Instead of just giving us the 30s lumens. Can you also give us the startup lumens for these?

There are some differences in this batch too. A couple of them don’t have the prettiest beam, some yellowing in the middle of the hotspot compared to the rest of the beam. Only one out of ten is above the BBL though. I also ordered some more from GB so we’ll see what the new batch looks like.

However, the tint shouldn’t matter too much because you shouldn’t EDC or use these lights excessively anyway. Only use them for calibration.

djozz
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maukka wrote:

However, the tint shouldn’t matter too much because you shouldn’t EDC or use these lights excessively anyway. Only use them for calibration.

I never EDC the few lights that I use for calibration, I keep them treasured in a holster to keep the lens clean and only take them out for measurements.

link to djozz tests 

“I used to think that top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that thirty years of good science could address these problems. I was wrong. The top environmental problems are selfishness, greed and apathy, and to deal with these we need a cultural and spiritual transformation. And we scientists don’t know how to do that.”   (Gus Speth)

gorb507
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interested
Pls

Gorb507

Fady
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Interested, I’m in for a kit, Thanks!

maukka
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Interest list updated.

I’ve got 20 Convoy S2+ from Gearbest’s EU warehouse coming in and they will hopefully arrive next week. I’ve got enough BLF348s for the first 10 on the list now so they will be served quite soon, but have ordered 12 more from China.

edit: forgot I already sent one BLF348 light to an early bird

nkresho
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I’m in for a set please.

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I’am in thank you.

Micael

Texas_Ace BLF Calibrated Lumen tube

maukka
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First BLF348 batch measured.

iosala
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I am in for a set olso.
Please and thank you Smile

SKV89
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I’m surprised the tint in the same batch of 219b emitters can range from -0.0045 to 0.0024 and the tint from 4568k to 5119k. But fortunately all of these have better tint than the average 219c.

Are you going to send them based on the number? Since I’m number 5, I would be happy to get 1105 Big Smile

maukka
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SKV89 wrote:
Are you going to send them based on the number? Since I’m number 5, I would be happy to get 1105 Big Smile

These will be sent in random order. And the number 1101 is already out so you would’ve been out of luck anyway Wink

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