How shades reduce the brightness of lamps

I found out how much the shade reduces the brightness of the LED lamp.
To do this, I conducted an experiment to measure the luminous flux (total amount of light) and illumination of five LED lamps in their original form and with the shade removed.

I took five different lamps (mostly with neutral light, since I don’t mind).

The lamps’ caps were torn off, and two measurements were made in the integrating sphere – with and without a canopy.

Here are the results.

For bright lamps, giving 800-1200 lumens, removing the cap increased the luminous flux by 5-8%. Removing the cover for a 430 lumen lamp increased the luminous flux by almost 10%.

Apparently, different lamps have different transparency of the plafond, so the difference in luminous flux with and without a plafond for the Start lamp is the lowest.

If you need directional light (for example, when growing plants), removing the cap from the lamps is even more effective, because the shade diffuses the light, directing it to the sides and even slightly back.

I conducted a second experiment, measuring the illumination at a fixed distance of 25 cm from lamps with and without a shade.


Illumination without a plafond increases by 80-115%.

Many of those who use conventional LED lamps for growing plants take off their caps and do the right thing: for the same money, plants get twice as much light.

© 2021, Alexey Nadezhin

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