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

[moderator007]

Has anyone tried sixty645’s method for calibration?

Building a "light box" for measuring lumen output

Budgeteer, I wish you good luck with your light box. When you make a measurement on a light you measure of course the lux level (L) in the box and need to know the calibration factor K in: lumens = K * L It is in fact quite easy to find the factor. You need some good parallel light, for instance a thrower with a uniform hot spot and another luxmeter. Calculate the area (A) in square meter of your light input port in the box (easy if you made the hole round, square or rectangular). Tilt …

Help with my D.I.Y. Sphere Calibration

The question about calibrating a sphere, I have answered several times since 2011. Perhaps it needs to become sticky’d. There is a very simple, scientific way to do the calibration, without guesswork about some stock lights output. All you need is a parallel beam of light (a thrower) and a luxmeter and the formula lux x hole area (in square meters) = lumens The method is described here: and also here: