ARRRRRRRRRRRR!!! I didn’t catch that until just now…… 5.XX volts in the battery left. 
The readings were not only off they were scattered. They were all high, but not even by the same percentage. That pretty much took care of it. Now to go back and make updates all over the internet.
<3
Hey guys, am I calibrating my sphere based on the MID mode from (low,mid,high) on the driver?
Yeah, Mid.
Thx, was sanding down my sphere and wanted to make sure before I taken too much material off.
I use the BLF348 for the low calibration and the mid mode of the S2+ for the mid range calibration but honestly if the mid mode on the S2+ is good the 348 has always matched up as well.
This gives me a chuckle! My first measuring space was the small bathroom in the house and now, and you may have seen it, but I have an integrating 68 quart Coleman cooler. So, I call them 'Coleman Lumens'.
TK, Absorbing yours and others comments about determining OTF output with a DMM and improving my technique on that front, I've realized that OTF lumens are the real test... and has saved me $40.00 for a new clamp meter. This discussion on throwier v's flooder lights really helps me, going forward, on how to calibrate the readings (so far, 25 lights & combinations) with my Budget Lumen Measuring Rig.
Maukka, Your work is very much appreciated. Thank you!
Hi Maukka,
Are you still selling calibrated lights? I am from the Philiipines and I want to use your calibrated lights for my lumentube.
Yes, I’ll send you a message.
Thank you very much!
Hi Maukka!
I would like to buy a light for my 150mm tube built by ZozzV6 (he used your lights set to set the filters)
I think one light with 2 known steps should be enough to double check the tube now and then?
One brightness setting per calibration light is plenty, since something catastrophic would have to happen to the lux meter for it not to be linear. Using two lights is recommended as small differences in beam profile, CCT and CRI helps checking for multiple possible issues and also reveals problems in integration and or meter if the initial values start to drift.
It’s normal for the lumens for both lights to be not exactly spot on as reported because of lux meter sensitivity inaccuracies, but if the difference between them changes suddenly, that’s a good indicator of something gone wrong with the setup.
I have 5 BLF348s left, but only one low CRI S2+. None of them have been measured at the moment.
I have 3 high CRI S2+ with SST20 4000K coming in shortly, but if you want to check your meter and sphere against a low and high CRI lights, I can have the S2+ and BLF348 bundled for you tomorrow. The SST20 versions will be available next week at the earliest.
I will configure these new SST20 S2+ for 100% mode only. They have 3x7135 chips and are quite idiotproof in this configuration.
idiotproof sounds like made for me ;)
i just want a easy (and non expensive) way to check my equipment
whatever you suggest - i will "maukka said so..." use against any doubts :D
Hi everyone,
I bought the calibration lights from Maukka (great service, and super quick delivery!) but after “calibrating” my lumen tube and getting the multipliers for the two calibration lights, all my other lights are reading quite low.
Here’s what my tube looks like. I’m not sure if it’s just a bad design and if I need to tweak it or start again in a different shape, or…?
I make sure to cover the glass panel with a black cloth when a light is sitting on it. I’ve tried putting a piece of paper under the glass to act as a diffuser but it doesn’t really change the accuracy of the results, it just lowers the lux reading. I can in fact get the lux : lumen ratio almost 1:1 with my calibration lights this way, but it still makes all my other lights read either far too high or far too low.
Am I missing something really obvious?
Welcome to the world of real lumens.
Joking aside, could you list some lights and their emitters and their outputs that you have tested? Preferably on some lower level like at 1x7135 on that Emisar you seem to have.
For good integration, usually more bends than one with PVC tubes is useful. Also a white surface at the input port is preferred in addition to some diffusion.
I bought some white PVC piping the other day and started fiddling and testing, making various perspex diffusers of different opaqities (positioned just before the first bend), and entrance hole reducers with aluminium tape on the inside (both do help significantly, in making light bounce around a bit in the entrance cavity) , and I must say that it is a real challenge to make this system really integrate. And everything after the first bend does not add to integration, extra bends mostly reduce the light. In the end I got reasonably recognisable measurements for the common reflector flashlights (if pointed straight down on the diffusor!), but a zoomie in flood modus was over 25% off. Although it provides ballpark numbers, I’d say it is more of a light reducer than an integrator. Unexpectedly, my pipe design does not change CCT that much but does increase duv enormously. If you look at the spectrum I can see why: both the blue peak is reduced, and a broad band around 600nm, result: green. The portion over 630 nm is increased again. This may all be the result of the specific type of PVC that I got (it looked plain white though). I may do a post about my findings, but then, maybe not. My conclusion: I stick to spheres for integration 
Cool info, djozz! I’ve also wanted to make a PVC tube for checking how they integrate.
That is not such a great design. Firstly, don’t use a black cloth, that absorbs a lot of light. You want to use something reflective to bounce the light towards the sensor.
Second is your not really blending up or diffusing the light. A tight focused beam light is probably going to read higher than a wide focused beam. You may be getting direct reflections on the sensor which will make the readings wonky. The middle section doesn’t need to be so long. Just having more bends will help break up the light beams. Try removing the end where the sensor is and shine your light in normally. See if the area where the sensor is gets “smooth” light or splotchy light. You’ve seen the Texas_Ace Lumen Tube, right? Link is in my sig. It’s got more bends plus 3 translucent diffusers to help smooth out the light before it gets to the sensor. This smoothing or “integrating” of the light is the key job of an integrating sphere. Yours is severely lacking in this department.
Lumen tubes are also sensitive to distance. Having a piece of glass that you sit the light is convenient, but it also moves the led closer or further away depending on the reflector or optic depth. This leads to inconsistencies. This doesn’t matter as much with ball shaped integrating spheres. Try making those other changes and see if using the glass is okay for you or not.
I just got the three SST20 4000K CRI90 Convoy S2. So two more BLF348 S2+ kits are ready to go after one S2+ was reserved for M4D M4X.
I recenltly made one myself and indeed, getting it accurate for all type of lights is VERY difficult.
However, i ended up with a setup which is quite satisfying and quite accurate
And yes, welcome to the world of real lumens. Only just now i realize how unreliable the human eye seems to be.
I did not realize how fast output drops, how much effect temperature, cell type, condition and charging percentage affects the output. Now i do.