I have a TA lumen tube that works great. I’d like to see how well calibrated it is and fine tune it if needed. Am looking for someone in US with a tube or sphere they have calibrated. I know several members purchased lights from an overseas member which were tested on his sphere. If anyone is willing to assist, let me know. I can mail you a basic 18650 light and include a return envelope, shipping label, and $ for shipping light back to me. Thanks.
I think there is a list of lights you can buy that from factory have good calibration.
Thanks. Yeah, that’s true. I may just do that.
Lights vary from batch to batch, there so many things that can make a few percent lumens difference between the same lights.
I know you probably already saw the thread but for the $73 bucks it’s well worth the money to get as close as you can and later on if you buy another tube or replace light meters you still have the lights to calibrate by. WTS: Calibration lights for DIY integrating spheres / lumen tubes - 67 € -
Thanks 007. Yep, you are correct…I’ve seen that thread 
I was trying to avoid buying 2 more lights that I already own. Of course the ones I have haven’t been tested in a calibrated sphere.
I’ll do it WillyD. I have both a TA Tube & a set of maukka calibration lights. PM me & we can work out details. 
Just be sure to send him a light with a constant regulated mode.