Does high efficiency white LED look brighter than filament lamp in same luminous flux? This is a rather complex problem. It involves properties relate to human optic nerve system, and also some optical concepts. From the view of the optical measurement, as long as different testing LED lights have same luminous flux, they should look like the same in human eyes. No matter what color they are. However, if the testing object is light radiance, the result will be different. Tow bundle of lights with same radiation energy but different color temperature, will look different in human eyes. A lot of technician did not take these differences into account, leading to the inaccuracy of their testing results. In their opinion, high efficiency white LED street light has been proved much brighter than filament lamps in all conditions.
If using luminous test to compare the brightness of high efficiency white LED and filament lamp, there is one point needs to be noticed: the object should within the same surroundings (consider the radiation energy from the ground reflection), otherwise, the result will be inaccurate.
When we design an indoor led lighting products application, the commonly used instrument for testing light intensity near the ground is illuminometer. However, even for the same lamp with same projectors and luminous flux, light intensity near the ground will be different due to different ground conditions. Similarly, we will recognize them as different light since they have different brightness. Illuminometer is a type of instrument typically used to measure light intensity though the optical energy caught by the sensors mounted on its head. When we measure the light near the ground, we are only measuring the lighting coming from light sources. What about other light reflected by the ground and walls? After absorbing and diffuse reflecting by the ground, some light energy converts into radiation energy. The amount of energy all depends on what material the ground and walls used and the construction of the entire room. In other words, light caught by illuminometer is just part of what we have “seen”. That is reason why when illuminometers gave out same measuring result, we feel different light brightness.