Many cheap "bright" LEDs are for sale but they are simply a dim one in a case that focusses the light into a very narrow but bright beam.
Good LEDs have the same brightness or more and have a wide beam angle.
Hi,
The most accurate indicators of the brightness of LED bulbs are the measured lumens or lux. Lumens measure the total amount of light output from a bulb. Lux measures how bright the light is on a surface at a specified distance.
In fact, no one understand my question. I do not ask about the intensity of light, my question was about how to examine it. And to know whether is good or bad? Thanks